Diseases / List of Toxic Diseases / Disease description:

Oiling
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INFORMATION AVAILABLE

GENERAL INFORMATION

CLINICAL CHARACTERISTICS & PATHOLOGY

INVESTIGATION & DIAGNOSIS

TREATMENT & CONTROL

SUSCEPTIBILITY & TRANSMISSION

ENVIRONMENT & GEOGRAPHY

 

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General and References

Disease Summary

 
  • Oil affects birds by oiling of feathers and the effects of the associated loss of waterproofing and flying ability, toxic effects of ingested, aspirated oil and inhaled oil vapours, and toxic effects on embryos if eggs are contaminated.
  • Oil affects mammals by oiling of the pelage, which may affect insulation, toxic effects of ingested or aspirated oil and inhaled oil vapours.
  • Oil spills should be reported to the appropriate authorities: in the UK to the Environment Agency (0800 807060), in the USA to the National Response Center (1-800- 424-8802).

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Alternative Names (Synonyms)

  • Petroleum Toxicity
  • Oil Toxicity

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Disease Type

 Toxic - Complex Chemical Compounds 

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Infectious/Non-Infectious Agent associated with the Disease

  • Petroleum products, varying from crude oil to refined light oils such as petrol (gasoline). N.B. Large scale oil spills account for only about 15% of the total quantity of petroleum released into the environment annually.
  • Most oil is introduced into the environment by intentional discharges from transport and refining operations, industrial and municipal discharges, disposal of used lubricants and other waste oils, urban runoff, river runoff and atmospheric deposition. Also from natural seeps.
  • Petroleum oils are mixtures of hydrocarbons (usually more than 75%) and non-hydrocarbons, and vary greatly in their chemical composition, even within a single class of product and even if coming from a single source. Composition also changes over time due to weathering: a combination of evaporation, oxidation, polymerization, dissolution and biological degradation of oil in the environment. 
  • Oils, unlike most pollutants (which mix with water and are diluted), remains concentrated at the surface of the water for long periods.
  • Many of the toxic effects may be due to polycyclic aromatic hydrocarbons (PAHs) (usually containing benzene rings); volatile components such as benzene, toluene and hexane are also highly toxic but evaporate rapidly; these are usually problematic only early during an oil spill, but may remain at toxic concentrations for longer in very cold weather .
  • Oils act in several ways:
  1. Physical - Loss of both waterproofing and insulation properties of plumage, leading to loss of buoyancy, increased metabolic rate (may be 400% of normal metabolic rate) to maintain body temperature, Chilling and Drowning. Also loss of ability to fly and to forage.
  2. Toxic - Irritation of skin and mucous membranes (ocular, respiratory, oral, gastro-intestinal). Frequently causes anaemia. Volatile components may cause pulmonary haemorrhage and oedema, also inhaled droplets may cause aspiration pneumonia. Acts as a non-specific stressor, may also have a specific immuno-suppressive effect. May have a direct toxic effect on the kidneys, increase mixed-function oxidase activity in the liver, affect salt-gland function and reduce growth rate.
  3. Reproductive - Small quantities of petroleum oil (a few microlitres) transferred from plumage to eggs may be embryo-lethal. Teratogenic effects may also be seen. Also longer-term reproductive effects, via alterations in oestrogen cycles and prolactin levels.

(J1.32.w6, J14.19.w1, B15, B18, B20.13.w10, B23.38.w2, B36.42.w42, D214.1.w1, N15.62.w1, P4.1990.w1, P9.1.w3, P10.28.w1)


About 15% of annual oil pollution is from oil spills. (B20.13.w10)

Infective "Taxa"

--

Non-infective agents

Physical agents

Indirect / Secondary

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References

Disease Author

Debra Bourne
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Major References / Reviews

Code and Title List

B11.35.w3, B15, B16.19.w1, B18, B20.13.w10, B23.38.w2, B36.42.w42, B284.18.w18, B335.4.w4, B335.5.w5, B368.4.w4, B368.6.w6, B368.8.w8, B368.10.w10, B369.w5, B369.w6, B377.12.w12, B377.13.w13, B377.15.w15, B377.17.w17, B378.7.w7
D6, D32, D160.App4.w12, D162.5.w5, D183.w3, D208.4.w4, D208.5.w5, D214.1.w1
J1
.32.w6
J3.70.w1
J14.19.w1
J30
.60.w1, J30.66.w2, J30.78.w1
J40.30.w2
J315
.2S.w2
J318.24.w1
J320.8.w1
N15.62.w1
P3.1961-1970.w1
P4.1990.w1
P9.1.w3
P10.28.w1
P14.1.w11, P14.1.w17, P14.2.w1, P14.2.w5, P14.2.w6, P14.2.w7, P14.3.w12, P14.3.w20, P14.3.w27, P14.3.w28, P14.3.w29, P14.4.w3, P14.4.w14, P14.5.w5, P14.5.w6, P14.5.w7, P14.5.w8
P20.1992.w4
P24
.327.w4
P62.14.w1

In Cranes
J40.46.w1

Other References

Code and Title List

B334.w3
D16
J1
.37.w3, J1.41.w1
J4.162.w1, J4.181.w3, J4.187.w1 
J7.19.w1, J7.30.w6
J9.215.w2, J9.342.w1
J13.61.w1
J17.4.w1, J17.20.w1
J22.220.w1
J26
.22.w1, J26.23.w1, J26.30.w2
J30.51.w1, J30.52.w1, J30.68.w1
J41
.66.w1
J135
.97.w2
J313.10.w1, J313.11.w2, J313.40.w3, J313.47.w1
N16
.66.w1
P1
.1991.w1, P1.1991.w2
P14
.3.w29, P14.5.w1, P14.5.w2, P14.5.w3, P14.5.w4
P15.1997.w1
V.w6

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Clinical Characteristics and Pathology

Detailed Clinical and Pathological Characteristics

General

  • Oil causes the barbules of feathers to stick together. (J30.51.w1)
  • Oiled birds lose waterproofing, insulation and buoyancy and have reduced ability to fly, swim, dive, feed or escape. There are also the toxic effects of ingested oil (encountered when preening, drinking contaminated water or eating contaminated food) and the effect on embryos of oil contamination of egg shells. 
  • Ingested oil also acts as a non-specific stressor and increases susceptibility to infectious diseases. 
  • Oil may have long-term effects on reproduction. (B334.w3)
  • Oiling may have effects on annual cycles such as moulting and nesting dates. (B334.w3)

(B15, B18, B20.13.w10, B36.42.w42, B334.w3, J30.51.w1, P9.1.w3, P4.1990.w1, D32)

Clinical Characteristics

BIRDS Oiled birds have reduced water repellency of feathers and reduced insulation. Their metabolic rate and food requirements increase; at the same time oiled birds tend to spend large amounts of time not foraging but attempting to preen the feathers. Affected birds become starved and emaciated, hypothermic, and stresses, in addition to which are the toxic effects of ingested oil. (P3.1961-1970.w1)

Birds which are found on the shore and brought in for rehabilitation are generally in poor condition. (P3.1961-1970.w1)

General and Plumage:

  • Birds may appear wet and chilled. (B20.13.w10)
  • Oiled birds out on the water may be seen splashing a lot due to flapping their wings in attempts to stay floating on the surface. (D160.App4.w12)
  • Affected animals may be beached or perched, being forced to leave the water because they are chilled (to reduce heat loss). (B20.13.w10, B36.42.w42, J318.24.w1)
    • Oiled birds tend to leave the water and preen "incessantly". (J320.8.w1)
    • Note: Birds stranded on shore, and perhaps weak, are at increased risk of predation. (J318.24.w1)
  • Oiled birds have reduced buoyancy; birds still in the water may be noted to float lower in the water than normal. (B36.42.w42, J320.8.w1)
  • It may be possible to smell oil contamination on the affected casualty. (B20.13.w10)
  • Oil may be visible on the feathers; particularly on individuals in which the plumage is normally pale in colour the individual may appear discoloured, dirty or unkempt. This is particularly obvious if the petroleum product involves is dark in colour. (B20.13.w10, B36.42.w42)
    • With light oiling, there may be a thin film of oil on the feathers. (J30.51.w1)
    • With heavy oiling both the buoyancy and mobility of the affected bird may be visibly affected. (J30.51.w1, J320.8.w1, P62.14.w1)
    • Heavily oiled birds may struggle to swim and find it impossible to fly. (B284.18.w18, J320.8.w1)
    • In Anas platyrhynchos - Mallard experimentally oiled by being placed onto water to which oil had been added, thermal conductance increased, indicating reduced insulation from the plumage. With higher levels of oiling, the resting heat production increased by about 37.5%, from about 80 to 110 kcal/kg/day, and the lower critical temperature shifted from about 12 C to about 25 C. Oiling of scaup (Aythya - (Genus); Aythya marila or Aythya affinis not specified) showed similar changes in resting heat production and a similar shift in lower critical temperature. The increase in thermal conductance, i.e. decrease in insulation, in the scaup was greater than that of the mallard: about 50% high for the heavily oiled scaup. Oiled scaup "may survive in oily water for a relatively short time." (J30.51.w1)
  • The external appearance may vary depending on the type of oil involved: in a spill involving a fish oil mixture, penguins were observed to be covered with a sticky, white, foul-smelling coat of oil, and were shivering. (N15.62.w1)
In addition to the effects on the plumage other signs may include:
  • Lethargy. (B20.13.w10)
  • Dermatitis. (B20.13.w10)
  • Skin may be reddened. (P4.1990.w1)
  • Conjunctivitis. (B284.18.w18)
  • Corneal ulcers (B284.18.w18, P4.1990.w1)
    • These may be caused by the irritant effects of oil and/or from sand irritation in birds becoming beached on sandy shores. (P4.1990.w1)
  • Respiratory distress. (B20.13.w10)
  • Dehydration: eyes appear oval and sunken, skin is tight and inelastic, PCV may be over 60%. (B11.35.w3)
  • Loss of weight and body condition, malnutrition. (B20.13.w10)
  • Thermoregulatory disturbance: (B20.13.w10)
  • Anaemia (pale mucous membranes) due to toxic effects of some petroleum oils; PCV may be below 30%. (B11.35.w3)
  • Diarrhoea due to gastrointestinal irritation from ingested oil. (B11.35.w3)
  • Neurological abnormalities such as disorientation and coma. (B20.13.w10)
  • Oiled individuals may be easier to catch than their non-oiled counterparts. (B20.13.w10)
  • NOTE: Many clinical signs and findings may be related to stress, dehydration, hypothermia (See: Chilling - Hypothermia) and starvation (See: Starvation in Waterfowl and Seabirds (with notes on hedgehogs)). (B20.13.w10, D183.w3)
    • A small amount of oiling may reduce insulation and water-repellency, leading to increased heat loss, shivering and, if adequate food is not available, use of body reserves. This decreases the bird's average density, leading to reduced dive length and depth, making it more difficult for diving birds to get food, leading to increased use of energy reserves and a "spiral" leading to death from exposure and starvation. (J313.11.w2)
  • Dehydration may occur due to decreased consumption of food, increased metabolic demands, loss of fluids from diarrhoea and decreased fluid absorption due to gastro-intestinal tract irritation by oil. (D183.w3)

Experimental data:

  • Nestling Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin, dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally, ate less than controls and those given lower doses of oil, and lost weight. The gulls passed oil in their droppings within 10 minutes of being given the oil. Some birds became weak on the fourth or fifth days of being given the oil, including two gulls which were moribund on the fifth day and one puffin which was weak on day four and died during the night. (J26.23.w1)
  • Body mass and body temperature, as well as water flux, plasma sodium and chloride, and food intake, significantly decreased in Larus glaucescens - Glaucous-winged gulls (Larus (Genus)) experimentally oiled with about 150 ml of Marine Bunker fuel (approximately No. 6 grade), despite their being fed and given free access to fresh drinking water. (J30.68.w1)
  • In Grus canadensis - Sandhill crane experimentally dosed daily with 2 mL or 10 mL Prudhoe Bay crude oil, several cranes regurgitated oil immediately after being dosed a second ime, and one developed respiratory noises indicative of inhaling some of the oil. Those given the higher dose (10 mL of oil) became lthargic over the course of the study, appeared weaker, were less willing to move when driven, and showed altered posture when standing and walking, with the head usually held close to the body and the breast appearing lower than in control birds, which held their necks extended and breasts slightly higher than their posteriors. Cranes dosed with 2 mL were intermediate in appearance. While all cranes, including those not dosed with oil, lost 11-13% of body weight by day four of the experiment, controls had regained most of their lost weight by day 12 while oil-dosed cranes did not gain weight during this period, although they did regain weight later. (J40.46.w1)

Clinical pathology:

  • NOTE: It is important to recognise that findings may be related not only specifically to toxic effects of oiling but to oil-related stress and, in birds which have been caught and brought into care, stress related to capture, handling etc. (B20.13.w10, D183.w3, J4.187.w1)
    • Larus argentatus - Herring gull adults brought into captivity, housed outside in individual cages within sight and sound of conspecifics, and which showed apparent behavioural adaptation (no apparent behavioural signs of stress after three days in captivity), showed marked and significant (P <0.05) leucocytosis, heterophilia and anaemia, which developed by as early as four days of captivity and did not return to base-line values by 28 days; the leucocytosis was due to the heterophilia; total and differential leucocyte counts varied widely between individuals and between days in a given individual. PCV was lowest at day 12 and remained at this level to day 20 then began to rise, but had not returned to base-line by 28 days. (J4.187.w1)
  • Haemolytic anaemia was noted in a number of Uria aalge - Common murre oiled with Bunker C or Bunker C mixed with other oils, with an average haematocrit of 37.7%, indicating a 25 to 30% reduction in red blood cells, but with considerable variation, some birds having a loss of more than 80% of their red blood cells, with a PCV of under 10%. Recovery from this anaemia was noted to be slow. (J311.10.w2)
  • Severe haemolytic anaemia with Heinz-body formation was noted in nestling Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin following experimental administration of Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally. PCV and haemoglobin levels were significantly (P<0.05) reduced in these birds, while the percentage of reticulocytes and the percentage of cells containing Heinz-bodies were significantly increased. In gulls dosed with 4 ml/kg bodyweight, the only significant change was a decrease in PCV (P <0.05); with 1 ml/kg there were no measured effects. (J22.220.w1)
    • Abnormalities noted in blood smears from nestling Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin, following experimental administration of Prudhoe Bay crude oil at 10 mg/kg bodyweight orally, included anisocytosis, poikilocytosis, reticulocytosis and formation of Heinz bodies. Transmission electron micrographs revealed both intracytoplasmic and intranuclear Heinz bodies, various abnormal cytoplasmic vesicles, degenerate mitochondria, lack of circumferential microtubules, abnormal shape and crenulation of the plasma membrane of the cells. Injecting gulls with phenylhydrazine (a known oxidant) resulted in similar lesions, while gulls made anaemic by haemorrhage showed reticulocytosis but not the other abnormalities. The findings further supported the hypothesis that the toxicity of the oil was due to oxidant chemicals. (J26.22.w1)
  • Increased percentage heterophils and decreased percentage lymphocytes were found on day five in nestling Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin, following experimental administration of Prudhoe Bay crude oil at 10 mg/kg bodyweight orally. (J26.22.w1)
  • In Larus glaucescens - Glaucous-winged gulls (Larus (Genus)) experimentally oiled with about 150 ml of Marine Bunker fuel (approximately No. 6 grade) and left oiled for four to five days, plasma sodium and plasma chloride decreased. (J30.68.w1)
  • Hyperproteinaemia (5.0-8.0 g/dl) at about 1-2 weeks after oiling has been described in Uria aalge - Common murre and found to be associated with an increase in acute phase proteins. (P4.1990.w1)
  • In Grus canadensis - Sandhill crane experimentally dosed daily with 2 mL or 10 mL Prudhoe Bay crude oil, there were no significant differences in haematological or biochemical parameters compared with controls. (J40.46.w1)

WATERFOWL

  • Oil may be grossly visible from a distance, particularly on pale-coloured birds. Feathers may be matted with oil and it may be possible to smell the oil. Oil may be found around the vent (cloaca). Eyes and nares may be matted with oil. The whole bird may be covered with oil, or only certain areas.
  • Birds may float lower in the water than usual due to loss of buoyancy, and may leave the water for any available islands, rocks etc.
  • Lethargy, dermatitis, conjunctivitis, respiratory distress may be noted, also disorientation and coma.
  • Often anorexic, even if food available.
  • Loss of condition may be noted (prominent breastbone) and can be severe after only 48 hours.
  • Diarrhoea may occur due to gastrointestinal irritation from ingested oil.
  • Dehydration (sunken eyes, tight inelastic skin, packed cell volume over 60%) may result from diarrhoea.
  • Hypothermia is common.
  • Corneal irritation and ulceration may be seen.
  • Deaths may occur due to hypothermia (see: Chilling/Hypothermia), Starvation, Drowning, or combinations of these.
  • Eggs (contaminated with oil from plumage of adult) may fail to hatch.
  • Ducks experimentally dosed with high doses of certain petroleum oils (diesel and a cutting oil) showed ataxia, incoordination, tremors and pupillary constriction. The oils contained organic phosphates, and cholinesterase inhibition was suspected. (J40.30.w2)

Clinical pathology:

  • Anaemia is common and may be severe: packed cell volume below 10% may be recorded. N.B. the PCV of a dehydrated bird may appear normal, despite anaemia. Low total proteins (total solids) is also common (0.3-1.9g/dl may be seen).
  • Haemolytic anaemia was found in wild seaducks (Melanitta fusca - White-winged scoter, Melanitta nigra - Black scoter and Clangula hyemalis - Long-tailed duck) during rehabilitation following oiling with Bunker C oil. Affected birds had reduced erythrocyte count, haemoglobin concentration and haematocrit. There were numerous immature erythrocytes visible in blood smears. (J1.32.w6)
  • Anaemia was noted two days after ducks were experimentally dosed with 2 g/kg bodyweight of fuel oil by stomach tube. (J40.30.w2)
  • Elevated non-protein nitrogen concentrations were noted after ducks were given diesel oil or fuel oil by stomach tube. (J40.30.w2)
  • Plasma cholinesterase levels were significantly depressed in ducks experimentally dosed with high doses of certain petroleum oils (diesel and a cutting oil); these oils contained organic phosphates. (J40.30.w2)

Chronic effects:

  • Reproductive effects - decreases in egg laying, fertilization rates and hatchability of eggs have all been reported in waterfowl following ingestion of oil.
  • Reduced growth and development.
  • Sea ducks Histrionicus histrionicus - Harlequin duck and Bucephala islandica - Barrow's goldeneye, sampled in 1996-1998 from areas of Prince William Sound, Alaska, which were heavily oiled during the Exxon Valdez oil spill in 1989, had significantly raised cytochrome P450 1A (known to be induced by oil-derived PAHs) compared to ducks of the same species from non-oiled areas, indicating probable exposure to oil. Certain polychlorinated biphenyl (PCB) congeners can also induce P450 1A, but were not detected in the ducks' tissues. The enzyme induction may be due to foraging on benthic invertebrates, which do not rapidly metabolise PAHs. It is possible that the remaining oil may have individual and population level effects, particularly for ducks like Histrionicus histrionicus - Harlequin duck which are at the lower end of the body mass range for sea duck survival in the subarctic. Records show that populations of some bird species, including Histrionicus histrionicus - Harlequin duck, have not fully recovered since the spill. (J313.40.w2)

N.B. secondary infections may be seen, associated with immunosuppressive effects of ingested oil. Aspergillosis is a common secondary problem in waterfowl (particularly seaducks such as eiders) being treated following oiling. Other problems including pododermatitis (Bumblefoot), hock swelling (Gout (with special reference to waterfowl)), keel sores (Keel Lesions) and feather damage (e.g. Feather Rot) also may be seen in birds during rehabilitation.

(J1.32.w6, J4.187.w1, J22.220.w1, J26.22.w1, J40.30.w2, J313.40.w2, B11.35.w3, B15, B16.18.w1, B20.13.w10, B36.42.w42, D183.w3, P4.1990.w1, P9.1.w3, P10.28.w1, P14.5.w7) 

MAMMALS Effects of oil on marine mammals may include "physical fouling, thermal imbalance, changes in enzymatic activity in the skin, interference with swimming, eye irritation and lesions, contamination of young, and occasional mortality." (B369.w5)

Pelage & Skin:

  • It may be possible to smell oil contamination on the affected casualty. (B20.13.w10)
  • Particularly on individuals in which the pelage is normally pale in colour the individual may appear discoloured, dirty or unkempt. This is particularly obvious if the petroleum product involved is dark in colour. (B20.13.w10)
  • Oil may cover the whole body or may be found in patches, such as on the top of the head, the head and neck, or the head, neck and anterior body, indicating probable rising out of the water through oil, or in patches on the belly, sides or back. All these patterns were seen in harbour seals (Phoca vitulina - Common seal) following oil exposure in Prince William Sound (Exxon Valdez spill). (B377.12.w12)
  • Dermatitis may be noted. (B20.13.w10, D183.w3, P14.2.w1)
  • Some harbour seals (Phoca vitulina - Common seal) following oil exposure in Prince William Sound (Exxon Valdez spill) showed dry, scaly skin. (B377.12.w12)
  • Chemical burns were reported in two oiled Galapagos sea lions Zalophus wollebaeki (Otariidae - Sea lions (Family)) following the Jessica oil spill in 2001; this was presumed to be caused by solar heating of oil exposed on skin. (J313.47.w1)
  • Experimental exposure of patches of the skin of Tursiops truncatus - Bottlenose dolphin, Grampus griseus - Risso's dolphin and a sperm whale Physeter macrocephalus - Sperm whale showed temporary decreases in circulatory perfusion in the contact area and transient damage (detected in skin biopsies) to cells in the epidermis, with the stratum germinativum and dermis affected only by longer exposures. there appeared to be an inhibition of phospholipid synthesis activity following exposure to crude oil or gasoline; wound healing was not affected. (B378.7.w7)
  • Oiled individuals may concentrate on grooming more than normal. (J17.20.w1, J30.52.w1, B368.10.w10)
    • Ursus maritimus - Polar bears, exposed to oil by being placed in an oil-covered pool, groomed their paws and forelegs intensively and also tried to remove oil by means such as rubbing on the bars of the cage, or in snow. Grooming decreased over a period of five days despite the continuing presence of oil on the coat. (B368.10.w10)

Thermoregulatory:

  • Mammals which depend on their pelage rather than on a blubber layer for insulation may appear wet and chilled. (B20.13.w10)
    • Body temperature may be unstable (B20.13.w10); either hypothermia or hyperthermia may occur due to the effects of oil on the pelage causing clumping of the fur and removing the insulating air layer. (D183.w3, J30.60.w1, P14.2.w5)
    • In Enhydra lutris - Sea otters, pelt studies have shown a two- to four-fold increase in thermal conductance when oiled pelts are immersed in sea water. (J30.66.w2)
    • Oiled Enhydra lutris - Sea otters have an increased energy requirement in order to maintain body temperature in cold or even cool (15 C) water. (J30.60.w1)
    • Increased thermal conductance, energy expenditure and food intake has been demonstrated for the muskrat Ondatra zibethica (Muridae - Rats, mice, voles, gerbils etc. (Family)) after experimental oiling. (J30.52.w1)
    • Decreased core body temperature was observed in an Ursus maritimus - Polar bear when oiled by being placed in an oil-covered pool and then exposed to windy conditions at -16 to -24C. (B368.10.w10)
      • Compared to before oiling, subcutaneous temperature rose from 34.8 to 35.7 C and core body temperature decreased from 36.8 C to 36.5 C; in the presence of wind, temperatured decreased by approximately 1 C. It was calculated that although the increase in subcutaneous temperature was only 1C, overall heat loss was considerable and bears would need 1.5 times normal food energy intake. (B378.7.w7)
      • Additionally, in running bears, temperatures, particularly core body temperature, increased proportionately more in oiled bears, suggesting that oiled bears could risk hyperthermia while running. (B378.7.w7)

General:

  • Weight loss and loss of body condition, probably due to increased metabolic demand, hypoglycaemia, lethargy and anorexia. (B20.13.w10)
  • Dehydration. (B20.13.w10)
  • Anaemia (pale mucous membranes); (B20.13.w10)

Locomotion/Exercise effects:

  • Affected animals may be beached (B20.13.w10) or avoid entering the water. (J30.52.w1)
  • Swimming ability may be impaired; (D183.w3, P14.2.w1) individuals in the water may float lower in the water than normal due to loss of buoyancy. (B20.13.w10)
  • Harp seals (Phoca groenlandicus - Phoca - (Genus)) covered with Bunker C oil had difficulty in swimming and may have died of exhaustion. Halichoerus grypus - Grey seal pups off the coast of Wales may also have had difficulties swimming due to heavy oiling. (B378.7.w7)
  • North American river otters (Lontra canadensis - Canadian otter) experimentally exposed to oil (Prudhoe Bay crude, weathered for two weeks) in food, at 0.1 g oil every other day or 1.0 g oil every other day, showed reluctance to bound rather than walk on a treadmill and showed higher oxygen consumption when walking than did control otters. Oil-exposed otters also showed reduced numbers of dives when chasing fish, compared with control animals; this could reduce prey capture rates. (J30.78.w1)

Gastro-intestinal signs:

  • Diarrhoea may occur. (B20.13.w10)
  • Both oil toxicity and stress are believed to have contributed to gastrointestinal haemorrhage (resulting in melaena) and chronic gastric erosion. (B20.13.w10)
  • Ingestion of oil may cause gastrointestinal haemorrhage in Lutra lutra - European otter. (P14.2.w1)
  • In three Ursus maritimus - Polar bears exposed to oil by being placed in an oil-covered pool, and which ingested oil while grooming their contaminated fur, vomiting and diarrhoea were noted. (B368.10.w10)
  • Spraints (faeces) may visibly contain oil. (J17.20.w1)

Respiratory signs:

  • Respiratory distress may be noted. (B20.13.w10, D183.w3)
  • Inhalation may lead to pneumonia. (D183.w3)
  • Dyspnoea in Enhydra lutris - Sea otters, with resultant interstitial pulmonary emphysema. (B20.13.w10)
  • Inhalation of volatile hydrocarbons may result in mucous membrane inflammation, pulmonary oedema, pulmonary haemorrhage and pneumonia. (P24.327.w4)
Ocular lesions:
  • Ocular irritation appears to be a common feature of oiling in pinnipeds. (J320.8.w1)
  • Conjunctivitis is recognised as a common sign. (B20.13.w10, D183.w3, P14.2.w1)
  • Excessive lachrymation, acute conjunctivitis, swollen nictitating membranes, opacity of the cornea, corneal abrasion and even corneal ulceration may be noted; these may be common findings in oiled seals. (B335.15.w15, B378.7.w7)
  • Harbour seals (Phoca vitulina - Common seal) following oil exposure in Prince William Sound (Exxon Valdez spill) sometimes appeared to have difficulty in keeping their eyes open. (B377.12.w12)
  • Conjunctivitis and corneal ulceration have been seen in oiled seals. (D183.w3)
  • Corneal lesions attributable to oil exposure were observed in harbour seals (Phoca vitulina - Common seal) oiled in the Exxon Valdez spill in Prince William Sound, Alaska, in 1989. (D162.5.w5)
  • Ringed seals Phoca hispida (Phoca - (Genus)) experimentally exposed to water covered in crude oil quickly started excessive lachrymation and after a while had difficulty in keeping their eyes open. Severe conjunctivitis, swollen nictitating membranes and corneal abrasions and ulceration were noted within 24 hours, but the inflammation reduced once the seals were placed in clean water. (B368.4.w4, B378.7.w7)
    • Ocular problems may be exacerbated by highly viscous weathered oil due to the tenacity of the substance and its ability to trap debris such as sand and sticks. (B368.4.w4)

CNS signs:

  • CNS signs seen in oiled mammals may include weakness, lethargy, muscle fasciculations, ataxia, paralysis and seizures. These may be due to petroleum toxicity, particularly after contact with volatile agents, or may be related to secondary effects of oiling: hypoglycaemia, hypothermia or hyperthermia, electrolyte imbalances, or trauma. (D208.5.w5)
    • CNS signs may also be due to other illness present at the time of oiling. (D208.5.w5)
  • Lethargy has been noted. (B20.13.w10, B377.12.w12)
  • Neurological abnormalities such as disorientation and coma. (B20.13.w10)
  • Reduced reactions to humans. (B377.12.w12, D183.w3)
  • Oiled individuals may be easier to catch than their non-oiled counterparts. (B20.13.w10)
  • Some harbour seals (Phoca vitulina - Common seal) following oil exposure appeared sick, lethargic and tame (allowing close approach). Behavioural changes were thought to be associated with damage to brain neurons due to hydrocarbon toxicity. (B377.12.w12, D183.w3)
  • In harbour seals (Phoca vitulina - Common seal) following oil exposure in Prince William Sound (Exxon Valdez spill), deaths occurred probably due to neuronal damage thought to be related to inhalation of short-chain aromatic hydrocarbons. (B377.17.w17)
  • In Mustela vison - American mink experimentally exposed to oil externally (either a 1.5 cm-thick slick of Alaskan North Slope crude oil on seawater for one minute, or a 1.5 cm-thick slick of bunker C fuel oil on seawater for one minute) or internally by being fed diets containing 500 g of Alaskan North Slope crude oil or of bunker Coil per gram of food, behavioural changes were seen in the externally-exposed mink for five to 15 days, including lethargy or stupor, lateral or dorsal recumbency and blindness. The signs were compatible with hepatic toxicosis leading to hepatic insufficiency and thereby CNS abnormalities. (J13.61.w1)

Examples of clinical signs in different species:

  • In Enhydra lutris - Sea otters oiled in the Exxon Valdez spill, depression, respiratory distress (associated with interstitial emphysema) and diarrhoea were noted. Animals which did not survive after being taken into care for rehabilitation died from stress and shock. (B368.8.w8)
  • Skin ulceration, gastro-intestinal tract bleeding, respiratory distress and respiratory tract bleeding have been seen in oiled seals. (D183.w3)
  • Subadult crabeater seals Lobodon carcinophagus (Phocidae - Seals (Family)) oiled by diesel from the Bahia Paraiso in Antarctica were observed listless and with blood-tinged nasal discharge and blood-tinged faeces. (B368.4.w4)
  • Some harbour seals (Phoca vitulina - Common seal) pups had elevated blood hydrocarbon levels and "appeared unhealthy" for a time following the Exxon Valdez spill in Prince William Sound, Alaska, in 1989, but all recovered. (D162.5.w5)
  • Enhydra lutris - Sea otters which died after being oiled in the Sea Empress spill and taken for rehabilitation, most commonly showed a terminal shock syndrome with hypothermia, lethargy and commonly haemorrhagic diarrhoea. This was more common (72% versus 22%), and occurred more rapidly, in heavily oiled otters versus lightly oiled otters, indicating that oiling was an important contributing factor in development of the condition, although there may also have been a role or reaction to confinement and handling. In heavily or moderately oiled otters, shock was present at the time of presentation or developed within 48 hours, while in lightly oiled otters it developed during the second week in captivity. Anorexia was common in the otters and convulsions were often seen terminally. (J26.32.w1)
  • In three experimentally oiled Ursus maritimus - Polar bears, abnormal (excessive) grooming, vomiting, diarrhoea. One bear dies, a second was euthanased, due to renal failure and the third required extensive treatment. 
  • In domestic cattle calves given "sweet" (low sulphur) crude oil, "sour" (high sulphur) or kerosine, by stomach tube, clinical signs included anorexia, significant weight loss, mild depression and in most cases decreased plasma glucose. Oil was visible in the faeces of all individuals given multiple doses of oil, and those of some individuals given kerosine or sweet crude became rather dry. Vomiting and moderate to extreme bloating were noted with the crude oils, particularly the volatile sweet crude oil, but not with the kerosine. Clinical signs of pneumonia and pleuritis (due to aspiration pneumonia) with shallow rapid respiration, increased heart rate, lowered head and neck, reluctance to move, anorexia, depression, weakness, constipation, oil-stained mucous discharge, a dehydrated appearance, and in some animals also shivering, slight incoordination, head bobbing and mental confusion were noted in some calves given kerosine or sweet crude oil. (J4.162.w1)

Clinical pathology:

  • Note: Haematological and biochemical data can be very important for clinical decisions regarding treatment of oiled animals, however in clinical oiling situations it is generally not possible to distinguish between direct (toxic and/or stress) effects of the oil and those related to stress of capture, handling and rehabilitation procedures. (J13.61.w1)
  • In Enhydra lutris - Sea otters oiled following the Exxon Valdez spill and taken in for rehabilitation, common haematological abnormalities were lymphopaenia and leucopaenia, often with a left shift and anaemia. Biochemically, azotaemia (probably prerenal in most cases, associated with shock or dehydration), hyperkalaemia (probably related to diarrhoea and gastrointestinal haemorrhage), hypoglycaemia (probably due to anorexia), elevated serum transaminases (indicating hepatocellular leakage and probably associated with anorexia) and hypoproteinaemia/hypoalbuminaemia (probably related to diarrhoea and gastrointestinal haemorrhage) were recorded. Heavily oiled otters showed more clinical pathological abnormalities than did lightly oiled otters. (J26.32.w1)
    • Note: severe leukopaenia and a left shift seen in oiled Enhydra lutris - Sea otters, indicating a severe inflammatory response, may be partly due to severe stress and use of corticosteroids. (B20.13.w10)
  • Levels of various liver enzymes such as AST and ALT may be increased. (B20.13.w10)
  • In harbour seal (Phoca vitulina - Common seal) pups oiled following the Exxon Valdex oil spill and taken in for cleaning and rehabilitation, blood LDH (lactate dehydrogenease) levels were high initially and then fell rapidly; the high levels were thought to be related to the "stresses associated with oiling, capture and handling." (B377.13.w13)
  • Anaemia was noted in some Enhydra lutris - Sea otters during rehabilitation following the Exxon Valdez oil spill. (P14.3.w28)
  • Reduced PCV was noted in two harbour seal (Phoca vitulina - Common seal) pups captured early during the Exxon Valdez spill, and which did not survive. The exact cause of the reduction in PCV was not clear; factors which were considered to have contributed to the deaths of the pups included contamination with oil early in the spill, multiple transfers between facilities and inconsistencies in feeding and rehabilitation protocols. (B377.13.w13)
  • Anaemia may result from absorption of volatile hydrocarbons. (P24.327.w4)
  • In North American river otters (Lontra canadensis - Canadian otter) experimentally exposed to oil (Prudhoe Bay crude, weathered for two weeks) in food, at 0.1 g oil every other day or 1.0 g oil every other day, haemoglobin levels declined compared to control otters. (J30.78.w1)
  • In three Ursus maritimus - Polar bears exposed to oil by being placed in an oil-covered pool, peripheral haemolysis, erythropoitic dysfunction and renal abnormalities were notable: microcytic hypochromic anaemia, elevated serum bilirubin, urea, creatinine, uric acid and inorganic phosphate were detected as well as hyponatraemia. increased cholesterol and plasma cortisol indicated an exposure-related stress response. (B378.7.w7)
  • In Mustela vison - American mink experimentally exposed to oil externally (either a 1.5 cm-thick slick of Alaskan North Slope crude oil on seawater for one minute, or a 1.5 cm-thick slick of bunker C fuel oil on seawater for one minute) or internally by being fed diets containing 500 g of Alaskan North Slope crude oil or of bunker Coil per gram of food, changes were seen in a wide variety of haematological and biochemical parameters. (J13.61.w1)
    • In samples taken one week after exposure, red blood cell count, white blood cell count, segmented neutrophil counts and relative frequencies and fibrinogen levels showed significant variances between groups; differences were greatest for those externally exposed to Bunker C fuel oil. The increase in red cell count may have indicated a stress response causing splenic contraction and rbc release; leucocytosis in mink exposed to bunker C fuel oil but not to Alaska North Slope crude may indicate a higher physiological stress associated with the bunker C oil. Biochemically, individuals exposed externally had significantly altered values compared with control mink, with alterations in sodium (decreased), chloride (decreased), calcium (decreased), creatinine (increased), total protein (decreased), alanine transaminase (ALT) (increased), creatine kinase (CK) (decreased), alkaline phosphatase (AP) (increased) and gamma-glutamyltransferase (GGT) (increased); alterations were greatest for the mink exposed to the crude oil. Changes in sodium, chloride and calcium may have been associated with GIT disturbances including anorexia and diarrhoea, while decreased sodium and chloride may also have been associated with toxic effects of oil ingested by grooming. The decreased CK in externally exposed mink relative to the other groups was probably because these animals were relatively lethargic and inactive, therefore showed less resistance to capture. The increased ALT, AP and GGT, and reduced total protein, were consistent with liver toxicity; the increased creatinine indicated direct toxic effects on the kidneys with possibly decreased glomerular filtration. (J13.61.w1)
    • In samples taken after the mink had weaned their pups, while all mean values for haematological parameters were within reference ranges for this species, mean reticulocyte counts were decreased and segmented neutrophil counts were lower, while the number of leucocytes was increased. Effects were most severe in individuals exposed to bunker C fuel oil in the diet; those exposed to Alaska North Slope crude in their diet showed similar changes of a lesser degree while mean reticulocyte values in externally exposed mink were also lower than in controls. The reduced number of neutrophils in mink following ingestion of oil may indicate reduced neutrophil production, possibly due to toxic effects on haematopoietic stem cells. Biochemically, differences from controls were seen in aspartate transferase (AST) (higher), alkaline phosphatase (higher), gamma-glutamyltransferase (higher), lactate dehydrogenase (higher) and cholesterol (higher). Raised AST, AP, LDH and cholesterol in externally exposed mink, raised GGT in mink internally exposed to bunker C fuel oil, and raised LDH all indicated mild hepatic damage. (J13.61.w1)
  • "An animal that has truly recovered would be expected to have serum LDH activity and values for other hepatic enzymes within reference ranges at the time of release." (J13.61.w1)
  • In domestic cattle calves given "sweet" (low sulphur) crude oil, "sour" (high sulphur) or kerosine, by stomach tube, some calves developed a reduced plasma glucose content; this was a consistent finding in those given the sour crude. In calves developing aspiration pneumonia due to the oil, findings included mild to moderate haemoconcentration (increased PCV, haemoglobin, total proteins and BUN), together with transient hyperglycaemia (108 to 168 mg/100 mL) and initial leucopaenia (reduced neutrophils, lymphocytes and eosinophils) followed over two to three days by a relative increase in neutrophils while the total WBC count either remained lowered, returned to normal, or became elevated. (J4.162.w1)
  • Note: Changes in blood parameters can be complex, with interactions between components of responses, and associated with other factors such as season and diet, which may give misleading results if only one parameter is measured. (J1.37.w3)

Long-term & population effects:

  • Enhydra lutris - Sea otters, sampled in 1996 to 1998, in areas of Prince William Sound, Alaska, that were heavily oiled by the Exxon Valdez oil spill in March 1989, showed significantly higher induction of phytochrome P450 1A (an indicator of exposure to PAHs) than did otters from unoiled areas, indicating continued exposure to oil. Sea otter populations in the oiled area have also shown a slower population recovery than expected and analysis of carcass collection data indicates that sea otters in the oiled area have had reduced survival. Reduced survival was greatest for animals born prior to the spill but was still evident in young animals born after the spill. Animals from young cohorts at the time of the spill (e.g. yearlings at the time of the spill) showed substantially higher mortality rates in the first years after the spill and improved annual survival later, while mature breeding animals (five years and older) have shown strongly increasing mortality rates with time. (J135.97.w2)
REPTILES
  • Sea turtles may float unevenly. (B20.13.w10)
  • In sea turtles, dermatological damage, respiratory effects, decreased digestive efficiency, haematological damage and associated immune reaction and decreased salt gland efficiency may occur. (B369.w6)
  • Tar may be present caked in the mouth, oil may be present on the animal and locomotion may be impaired (particularly in hatchlings. Oil may also be found in the nares, eyes and faeces. (D228.4.w4)
  • Chelonia (Testudines - Turtles and Tortoises (Order)) soiled with diesel have shown ocular irritation, dermatitis and lethargy soon after oiling, followed by development of respiratory distress and sloughing of skin, later broken nails and chipped beaks, also secondary bacterial cutaneous ulcerative disease with Citrobacter freundii. (P14.4.w3)
    • Lesions on the plastron developed initially as pinpoint pale yellow spots, which developed to a network of fine yellow striations and in some animals continued to reddening of the plastron and ulcerative lesions of the shell. (P14.4.w3)
  • Skin and exposed mucous membranes:
    • Caretta caretta - Loggerhead turtles experimentally exposed to oil showed sloughing of mucous membranes (periorbital conjunctiva, nasal and oral mucosa) and skin, particularly the skin of the neck, inguinal region and axillae. Under the slough, the skin was soft and light red in colour; it lacked the normal leathery texture of turtle skin. Skin was grossly normal by 40 days after exposure to oil. (P14.3.w29)
      • Note: the nature of the inflammatory response could break the integumentary barrier and allow entry of pathogenic organisms, resulting in localised bacterial infection and even septicaemia. (P14.3.w29)
  • Young sea turtles may die as a result of eating tar balls. (B369.w6)

Clinical pathology:

  • Up to a four-fold increase in leucocyte count, 50% reduction in red blood cell count and polychromasia were noted in Caretta caretta - Loggerhead turtles experimentally exposed to oil. Glucose levels were also reduced, but other serum chemistry values were less affected. (D228.4.w4, J52.28.w1)
AMPHIBIANS --

Incubation

BIRDS
  • Effects may be acute or chronic (B20.13.w10, B36.42.w42).
MAMMALS --

Mortality / Morbidity

BIRDS
  • Mortality can be very high in the vicinity of oil spills.
  • Detected mortality is probably lower than actual mortality, as only birds reaching the shore are counted in marine oil spills and small numbers of birds affected by minor spills may not be noticed.
  • Long-term effects e.g. on reproduction, are difficult to quantify.
  • Mortality may also occur due to predation of affected birds. (P62.14.w1)

(B20.13.w10, B36.42.w42)

  • Individuals which are already under stress, for example due to other pollutants, may be less able to cope with the effects of oiling. (B369.w4)
  • In the Exxon Valdez oil spill, Prince William Sound, Alaska, 1989, about 100,000-300,000 birds were estimated to have been killed, or some 10%-30% of the population. (J9.342.w1)
MAMMALS Recorded mortality of mammals following oil is variable.
  • Nearly 1,000 Enhydra lutris - Sea otters died following the Exxon Valdez oil spill. (B368.8.w8)
  • Enhydra lutris - Sea otters have been found dead associated with various oil spills (more than 100 in a spill in the Kuril Islands in 1946), while oil has also been considered as a reason for population declines in this species. (B368.8.w8)
  • Thirteen Lutra lutra - European otter were found dead following the Esso Bernicia spill at the Sullom Voe oil terminal, Shetland in 1978. Estimated mortality was at least 15% of the population, possibly up to 50% (depending on the estimated initial size of the population). (J17.20.w1)
  • Morbidity and mortality associate with oiling in pinnipeds appears to be very variable. In some instances, and sometimes despite visible evidence of heavy oiling, effects have been inapparent or negligible. In others, some ill-effects have been seen and/or a few individuals have been recorded dying due to the oiling, but in a few cases a number of animals have been found oiled and dead. Heavy oiling of harp seal (Phoca groenlandicus - Phoca - (Genus)) pups with Bunker C oil in the Gulf of St Lawrence was associated with increased mortality in the pups. Halichoerus grypus - Grey seal pups have been observed drowning after being covered with thick oil and unable to swim due to their flippers being stuck to their bodies. (B368.4.w4)
  • Harbour seals (Phoca vitulina - Common seal) were found dead following oil exposure in Prince William Sound (Exxon Valdez spill) with visible oiling and/or pathological lesions indicating mortality was associated with oil exposure. (B377.17.w17) 
  • Of three polar bears Ursus maritimus (Ursus - (Genus)) exposed to oil by being placed in an oil-covered pool, one died twenty six days after oiling and another required euthanasia three days later. The effects of oiling may have been exacerbated by stress due to the experimental conditions. The third bear survived but required several months of care to regain normal health. (B368.10.w10, B378.7.w7)

Pathology

BIRDS There are no consistent organ lesions indicative of oil exposure. (P14.2.w6)
  • NOTE: It is important to recognise that findings may be related not only specifically to toxic effects of oiling but to oil-related stress and, in birds which have been caught and brought into care, stress related to capture, handling etc. (B20.13.w10, J4.187.w1)
    • Larus argentatus - Herring gull adults brought into captivity, housed outside in individual cages within sight and sound of conspecifics, and which showed apparent behavioural adaptation, showed a 33% decrease in pectoral muscles after 28 days in captivity (microscopically consistent with atrophy), and multi-organ amyloidosis, with severe amyloid infiltration of the splenic arterial walls, sometimes by as early as four days after capture and in nearly all (six of seven) birds by 20 days; Amyloid was noted in other sites from eight days onward and was found in vessel walls in the liver, kidney, thyroid, pancreas and gonads. Adrenals also showed lesions, characterised by "moderate to severe diffuse vacuolar degeneration of catecholamin-producing cells." (J4.187.w1)
Gross lesions:

General:

  • Oil may be visible externally or found on examination of the inside of the ears, the vent, the trachea or the gastro-intestinal tract. (B20.13.w10)
  • The carcass may be dehydrated (loss of skin elasticity, skin difficult to reflect from underlying musculature). (J3.132.w)
  • Emaciation is a common finding. (B36.42.w42, J7.19.w1)
  • Larus argentatus - Herring gull nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, had greatly reduced subcutaneous fat; this was not seen in Fratercula arctica - Atlantic puffin nestlings given the same oil doses. (J26.23.w1)
  • Dehydration, with tissue that were dry, sticky and dark, were found in one of 103 Podiceps cristatus - Great crested grebe  and five of 86 Podiceps nigricollis - Black-necked grebe necropsied after being oiled in the Arabian Gulf spill in 1991. Emaciation was noted in 2.9% and 11.6% of the grebes respectively. (P14.3.w20)
  • Dehydration, with tissue that were dry, sticky and dark, were found in 18.3% of 71 Phalacrocorax carbo - Cormorant and 7% of 57 Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus)) necropsied after being oiled in the Arabian Gulf spill in 1991. Emaciation was noted in 4.2% and 15.8% of the cormorants respectively. (P14.3.w20)
  • Birds which die rapidly, for example due to toxic effects of inhaled petroleum vapours, may be in good or excellent nutritional condition. (P14.2.w7)
  • In auks (mainly Uria aalge - Common murre) oiled by the Torrey Canyon in 1967, and dying during attempted rehabilitation, the feathers were badly stained with oil, in poor condition, and not waterproof. In some individuals the skin appeared damaged and feathers fell out easily. Practically all birds dying in the first 11 weeks of attempted rehabilitation were emaciated, with low body weight (mean only 640 g), complete loss of both subcutaneous and visceral fat, and marked pectoral muscle atrophy. It was noted that "the pattern of mortality and pathological changes were strongly suggestive of severe stress and the presence of powerful irritants or poisons in the gut." (J315.2S.w2)
  • A study of Cerorhinca monocerata - Rhinoceros auklets (Laridae - Skuas, Terns, Gulls, Puffins, Auks (Family)) in the Southern Japan Sea found that dead oiled birds had lost one third of body, muscle and general organ masses, 60% of liver mass, more than 90% of subcutaneous fat and more than half of all fats stored in muscles and other organs, including bone marrow, which was almost entirely replaced with water. It was considered that these birds died not from the oiling per se but from "emaciation caused by starvation and nutritional exhaustion, accelerated by increased energy loss." (J313.40.w3)
  • In marine birds oiled in the Prestige spill in 2002 (mainly Uria aalge - Common murre, Alca torda - Razorbill, and Fratercula arctica - Atlantic puffin) also gulls Larus spp., Morus bassanus - Gannet, Phalacrocorax spp., Alle alle - Dovekie, Gavia immer - Common loon, Fulmarus glacialus - Northern fulmar and other birds, the main findings in birds found dead covered with oil were various degrees of oiling over the body surface (less than 10% to 100%), dehydration (loss of skin elasticity, skin difficult to reflect from underlying musculature), diarrhoea (liquid faeces surrounding the cloaca), and emaciation (severe pectoral muscle atrophy, absence of subcutaneous fat deposits, absence of abdominal fat deposits, serous atrophy of pericardial fat). Birds found dead but not covered in oil showed dehydration, diarrhoea and emaciation. Birds which had died during rehabilitation had findings of dehydration and diarrhoea, also broken feathers and skin erosions, and varying emaciation. (J1.41.w1)

Pulmonary:

  • Pulmonary haemorrhage and oedema may indicate exposure to some volatile components of oil. (P14.2.w7, B23.38.w2)
  • Pneumonia associated with inhalation of oil is reported sometimes. (B20.13.w10)
  • Oil may be present in the trachea and the lungs may be discoloured if oil has been inhaled. (B36.42.w42)
  • Pulmonary oedema may be present due to inhalation of fumes from oil; pneumonia may occur secondary to this. (P4.1990.w1)
  • Aspiration pneumonia may be present due to aspiration of either oil or gavage food mixtures. (P4.1990.w1, B23.38.w2)
  • Pulmonary haemorrhage was noted in some Phalacrocorax nigrogularis - Socrata cormorants oiled during the Arabian Gulf oil spill, January 1991, associated with the First Gulf War. (P1.1991.w1)
  • Lung consolidation and oedema was noted in 17 of 30 birds necropsied following the 1991 Fidalgo Bay (Washington) spill of crude oil. (P14.4.w14)
  • Pulmonary congestion and "cloudiness" of the air sacs was commonly noted in birds oiled with Kuwait crude following the Torrey Canyon spill. (J7.19.w1)
  • Pale watery fluid was noted "occasionally" in the lungs and airsacs of Podiceps cristatus - Great crested grebe (12.6%) and Podiceps nigricollis - Black-necked grebe (15.1%) necropsied after being oiled in the Arabian Gulf spill in 1991. (P14.3.w20)
  • In auks (mainly Uria aalge - Common murre) oiled by the Torrey Canyon in 1967, lungs of birds dying within the first four days after being found generally showed acute congestion; pneumonia was noted in some individuals. Air sacs were often cloudy. In birds which survived four days to three weeks, changes were similar; additionally, aspergillosis was found in three birds. In those surviving longer than this, aspergillosis was noted in 11 of 25 birds while lung congestion was noted in seven and cloudy air sacs in five. Drowning was also noted as a diagnosis in one or a few birds [data unclear].(J315.2S.w2)
  • In marine birds oiled in the Prestige spill in 2002 (mainly Uria aalge - Common murre, Alca torda - Razorbill, and Fratercula arctica - Atlantic puffin) also gulls Larus spp., Morus bassanus - Gannet, Phalacrocorax spp., Alle alle - Dovekie, Gavia immer - Common loon, Fulmarus glacialus - Northern fulmar and other birds, in 28% of birds which had died during rehabilitation there were multiple small whitish fungal plaques in the lungs, air sacs, kidney and liver (disseminated Aspergillosis). (J1.41.w1)
  • In Grus canadensis - Sandhill crane experimentally dosed with Prudhoe Bay crude oil, three of 10 cranes dosed with 10 mL per day had severe necrotising pneumonia or air sacculitis with associated oil. (J40.46.w1)

Gastro-intestinal tract:

  • Gastro-intestinal tract mucosa may be reddened; lumen may contain blood and/or oil. (B36.42.w42)
  • Oil may be present around the vent. (B36.42.w42)
  • Haemorrhagic enteritis may occur. (P14.1.w17)
    • Severe enteritis with coagulative necrosis and haemorrhage was noted in many birds (mainly Uria aalge - Common murre) oiled with Kuwait crude following the Torrey Canyon spill. (J7.19.w1)
  • In grebes (Podicipedidae - Grebes (Family)) impaction of the gizzard with bile-stained feathers may be noted. (P1.1991.w1)
  • Oil was found in the intestinal lumen of 11 of 30 birds necropsied following the 1991 Fidalgo Bay (Washington) spill of crude oil. No associated enteritis was seen. (P14.4.w14)
  • Oil was not found in the gastro intestinal tract of Larus argentatus - Herring gull nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, although Fratercula arctica - Atlantic puffin nestlings given the same oil doses often had mild oil staining of the ventricular cuticle and the intestines often contained small globules of oil. No gross lesions were found in these birds. (J26.23.w1)
  • Signs of oil were found in the jejunum, caeca and colon of 22.3% of Podiceps cristatus - Great crested grebe and 17.4% of Podiceps nigricollis - Black-necked grebe necropsied after being oiled in the Arabian Gulf spill in 1991. (P14.3.w20)
  • Inflammation of the small intestine, with petechiae or larger haemorrhages, was seen in 50.5% of Podiceps cristatus - Great crested grebe and 33.7% of Podiceps nigricollis - Black-necked grebe necropsied after being oiled in the Arabian Gulf spill in 1991; a few birds had proventriculitis, one had colitis. (P14.3.w20)
  • Cloacal impaction with urinary material was found in seven of 189 Podiceps cristatus - Great crested grebe and 35% of Podiceps nigricollis - Black-necked grebe necropsied after being oiled in the Arabian Gulf spill in 1991. (P14.3.w20)
  • Gastrointestinal tract inflammation (usually haemorrhagic suffusion of the walls of the small intestine, but with 12 cases of proventriculitis and one of colitis) was noted in 63.4% of 71 Phalacrocorax carbo - Cormorant and 45.6% of 57 Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus)) necropsied after being oiled in the Arabian Gulf spill in 1991. Signs of ingested oil were seen in 10% and 28.1% respectively, mainly in the proventriculus, small intestine and colon. (P14.3.w20)
  • In auks (mainly Uria aalge - Common murre) oiled by the Torrey Canyon in 1967, enteritis was a common finding in birds dying in the first four days of attempted rehabilitation, with the most severe lesions in the duodenum. Enteritis was considered to be simple inflammatory in some birds, severe haemorrhagic with severe loss of blood in some birds, and in some there was a coagulative necrotic condition with sloughing of the mucosa. (J315.2S.w2)
  • In marine birds oiled in the Prestige spill in 2002 (mainly Uria aalge - Common murre, Alca torda - Razorbill, and Fratercula arctica - Atlantic puffin) also gulls Larus spp., Morus bassanus - Gannet, Phalacrocorax spp., Alle alle - Dovekie, Gavia immer - Common loon, Fulmarus glacialus - Northern fulmar and other birds, the main findings in birds found dead covered with oil included diarrhoea (liquid faeces surrounding the cloaca) while within the ventriculus, proventriculus and intestines, dark material (similar to that on the skin, consistent with oil), was found, also petechiation of the mucosa. Birds found dead but not covered in oil showed diarrhoea and in some birds oil in the intestines. Birds which had died during rehabilitation had diarrhoea and a few had ventricular ulcers. (J1.41.w1)

Liver:

Kidneys:

Musculo-skeletal:

  • Pododermatitis (Bumblefoot) was sometimes noted in Phalacrocorax carbo - Cormorant and Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus)) necropsied after being oiled in the Arabian Gulf spill in 1991. (P14.3.w20)
  • In auks (mainly Uria aalge - Common murre) oiled by the Torrey Canyon in 1967, arthritis was noted in three of 11 birds dying at four days to three weeks during attempted rehabilitation, and in more than half of those dying later than this. (J315.2S.w2)

Other:

  • Salt glands may appear swollen. (B36.42.w42)
  • Adrenals may be enlarged. (B36.42.w42)
  • The heart appeared dilated, with flaccid ventricles and haemorrhagic suffusion on the epicardium, in 23.9% of 71 Phalacrocorax carbo - Cormorant and 7% of 57 Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus)) necropsied after being oiled in the Arabian Gulf spill in 1991. (P14.3.w20)
  • Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, had moderate to very dark brown discolouration of the liver, spleen, kidney, skeletal muscle and blood. The weight of the thymus and the bursa of Fabricius were reduced in the gulls, while the salt glands, adrenals and liver of the puffins increased in weight. (J26.23.w1)
  • In auks (mainly Uria aalge - Common murre) oiled by the Torrey Canyon in 1967 and dying during attempted rehabilitation, myocarditis and splenomegaly were each noted in one or a few birds [data unclear], and adrenals appeared larger than expected in some birds, although the weights of the adrenals varied widely from 73 mg to 297 mg. (J315.2S.w2)
Histopathology:
Lesions, if present, may indicate specific toxic effects or non-specific stress. there may also be lesions indicative of secondary problems (e.g. gout secondary to dehydration).
  • Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, had histological lesions in the liver, spleen, bone marrow, kidney, bursa of Fabricius and adrenals. "Many of the lesions in these birds were interpreted as sequelae to a primary toxic hemolytic disease." Other lesions (e.g. lymphocyte depletion) were considered to indicate a non-specific stress reaction. (J26.23.w1)
  • Waterbirds "of several species" which died two weeks after oiling with Bunker C oil, showed "Presence of oil in the digestive tract, acute enteritis, pulmonary congestion and haemorrhage, hepatic lipidosis, bile pigment and hemosiderin in hepatocyctes and Kupffer cells, renal tubulonephrosis with hyaline droplets and tubular casts, splenic lymphocyte depletion, and adrenal gland necrosis." It was noted that interpretation of the findings was complicated by environmental stressors, debilitation and infectious diseases. (J26.23.w1, citing a 1973 report from Stanford Medical Center)

Pulmonary:

Hepatic:

  • Hepatic haemosiderosis was noted in 12 of 12 birds following the 1991 Fidalgo Bay (Washington) spill of crude oil; this finding is consistent with severe haemolytic anaemia associated with oiling. (P14.4.w14)
  • In Larus argentatus - Herring gull and Fratercula arctica - Atlantic puffin nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, Kupffer cells were greatly enlarged and were filled with gold-brown pigment (particularly in the gulls) and with degenerated erythrocytes (particularly in the puffins). The pigment partially stained with Prussian blue, indicating presence of some hemosiderin. In two gulls euthanased when moribund, there was multifocal acute centrilobular necrosis of hepatocytes; in other gulls individual hepatocyte necrosis and apoptosis was common. (J26.23.w1)
  • In grebes and cormorants (Podiceps cristatus - Great crested grebe, Podiceps nigricollis - Black-necked grebe, Phalacrocorax carbo - Cormorant and Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus))) necropsied after being oiled in the Arabian Gulf spill in 1991, livers showed hyperaemia (100%), oedema (53%), vascular wall oedema (32%) and thrombi (70%), mainly in the veins. Besides these indications of circulatory disturbance, 94% had disseminated hepatocyte necrosis and 74% showed vacuolar degeneration in hepatocyte cytoplasm, the vacuoles apparently being lipid-filled. In 24% of the birds hepatocyte nuclei were abnormal, with nucleic oedema, hyperchromatosis of the nucleic wall and Cowdry type A small eosinophilic inclusions (typical of herpes virus infections). In 24% of livers haemosiderin was present. Inflammatory reactions were rare. (P14.3.w20)
  • In marine birds oiled in the Prestige spill in 2002 (mainly Uria aalge - Common murre, Alca torda - Razorbill, and Fratercula arctica - Atlantic puffin) also gulls Larus spp., Morus bassanus - Gannet, Phalacrocorax spp., Alle alle - Dovekie, Gavia immer - Common loon, Fulmarus glacialus - Northern fulmar and other birds, brown pigment (consistent with haemosiderin) was present in the hepatocytes and Kupfer cells; urates were also found in the liver; similar findings were present in birds dying during rehabilitation and in those found dead without external oil (haemosiderosis was not present in those found dead without external oil and without oil in the gastro-intestinal tract). (J1.41.w1)

Splenic:

Bone marrow:

  • Larus argentatus - Herring gull nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, had hypercellular bone marrow compared to control birds, and contained mainly cells of the erythroid series. Fratercula arctica - Atlantic puffin nestlings given the same oil doses showed high cellular density similar to that of controls but contained numerous large phagocytes filled with either erythrocytes or golden-brown pigment; these were seen occasionally in the gulls. (J26.23.w1)

Renal:

  • In Fratercula arctica - Atlantic puffin nestlings, dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, five of six birds had diffuse lesions, consisting of renal proximal tubule cells containing prominent hyaline droplets in the cytoplasm, sometimes with many droplets swelling the cell. Tubules and collecting ducts contained granules and hyaline casts, and the droplets and casts were haemoglobin-positive. These lesions were not evident in Larus argentatus - Herring gull nestlings given the same oil dose. (J26.23.w1)
  • In grebes and cormorants (Podiceps cristatus - Great crested grebe, Podiceps nigricollis - Black-necked grebe, Phalacrocorax carbo - Cormorant and Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus))) necropsied after being oiled in the Arabian Gulf spill in 1991, the main lesions were tubulonephrosis, vasculopathy and glomerulonephritis. In detail, the lesions included hyperaemia (94%), oedema (47%), thrombi (41%) and haemorrhages (50%). In 82% of birds there was widening of the capillary loops and these were filled with erythrocytes. In 38% the parietal membrane of Bowman's capsule was activated, while the visceral membrane was activated in 82%; the capsular cleft was widened in 15 birds and contained free erythrocytes and detritus. The mesangium was either poorly developed or degenerated in a few of the birds. In 74% there was degeneration and necrosis of the proximal tubules, with the brush border partially destroyed and cells detached from the basal membrane; 15% of birds had casts. In the distal tubules and collecting tubules lesion mainly increased from proximal to distal, with degeneration and necrosis of epithelial cells, detachment from the basal membrane in some cases, and casts, mainly of detritus, in 74%. A slight interstitial infiltration of lymphocytes was noted in just 12% with local proliferation of lymphoid follicles in only two birds. (P14.3.w20)
  • In marine birds oiled in the Prestige spill in 2002 (mainly Uria aalge - Common murre, Alca torda - Razorbill, and Fratercula arctica - Atlantic puffin) also gulls Larus spp., Morus bassanus - Gannet, Phalacrocorax spp., Alle alle - Dovekie, Gavia immer - Common loon, Fulmarus glacialus - Northern fulmar and other birds, birds found dead and oiled had urates in the kidneys and deposits of haemosiderin in macrophages in the kidneys. (J1.41.w1)

Adrenals:

  • In Larus argentatus - Herring gull nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, acute to subacute focal/regionally multi-focal necrosis was found, usually at one end of one gland only. Lesions were seen in control gulls and those given lower doses of oil, but were less common (15 of 31 high-dose gulls, six of 64 low-dose/control, (P<0.005, c2 analysis). This was not observed in the dosed Fratercula arctica - Atlantic puffin nestlings. Also in the gulls, 15 of 31 given the high-dose oil showed depleted adrenal lipid (compared to three of 27 low dose/control gulls) and this was evident in three of six puffins given the high dose oil, and in none of 12 low-dose or control birds. (J26.23.w1)
  • In grebes and cormorants (Podiceps cristatus - Great crested grebe, Podiceps nigricollis - Black-necked grebe, Phalacrocorax carbo - Cormorant and Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus))) necropsied after being oiled in the Arabian Gulf spill in 1991, hyperaemia was present in 94%, haemorrhages in 55% and oedema and thrombi in 26%; the cells of the adrenals appeared diminished in 39%, vacuolic-foamy cytoplasm was noted in 61% and necrosis in 71%. Cortical cells showed foamy degeneration of the cytoplasm in 65%, disseminated necrosis in 90% and focal necrosis in some individuals. Nuclear inclusions typical of herpes virus, as seen in hepatocytes, were also noted in adrenal cortical cells. (P14.3.w20)

Bursa of Fabricius:

  • In Larus argentatus - Herring gull nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, lymphocyte depletion was found in 19 of 26 birds but in only one of 62 low-dose and control un-dosed gulls (P < 0.005, c2 analysis). In affected birds the cortex was thin or absent and the medulla contained a greatly reduced density of lymphoid cells. Additionally, alterations were seen in medullary stromal cells that were typical of infection with an adenovirus-like agent; these were present in 14 of 17 oil-dosed birds in one experiment but in only seven of 20 controls (P < 0.01, c2 analysis); lesions were severe in the oil-dosed birds but minimal in the control birds. (J26.23.w1)

Thymus:

  • In Larus argentatus - Herring gull nestlings dosed with Prudhoe Bay crude oil at 10 or 20 mg/kg bodyweight orally daily, lymphocyte depletion was found in 20 of 29 birds but in only two of 60 low-dose and control un-dosed gulls (P <0.005, c2 analysis). In affected birds the cortex was thin or absent. (J26.23.w1)

Gastro-intestinal tract:

  • In grebes and cormorants (Podiceps cristatus - Great crested grebe, Podiceps nigricollis - Black-necked grebe, Phalacrocorax carbo - Cormorant and Phalacrocorax nigrogularis - Socotra cormorant (Phalacrocorax (Genus))) necropsied after being oiled in the Arabian Gulf spill in 1991, the small intestines commonly showed loss of villous epithelium (62%) and loss of the tops of villi (27); a few birds (12) also had degeneration/necrosis of the crypts of Lieberkuhn, while many (44%) did not show proliferation in the crypts despite the loss of enterocytes. Hyperaemia was present in 65% and haemorrhages in 38%. Mononuclear cell (mainly lymphocyte) infiltration was present in 70% and heterophils in 38%. The lesions were considered to fall into the following groups: haemorrhages without inflammation (five birds), haemorrhagic enteritis (eight), lymphocytic enteritis (three) purulent-lymphocytic enteritis (eight). (P14.3.w20)

WATERFOWL

Experimentally, No. 1 light fuel oil, diesel oil, a low additive SAE 10W motor lubricating oil, a sulphuretted SAE 10-W-30 motor lubricating oil with a high detergent content, a cutting oil additive and a cutting oil formulated from the additive plus triglycerides and 80 mineral oil, given by stomach tube to wild-trapped and domestic ducks were all able to cause lipid pneumonia, gastrointestinal irritation, hepatic lipidosis (fatty liver) and adrenal cortical hyperplasia. In wild ducks found dead due to oiling, lipid pneumonia, gastrointestinal irritation and adrenal enlargement were evident. (J40.30.w2)

Gross Pathology:

  • Variable findings; may be minimal.
  • General - Emaciation is common, even only a few days after exposure to oil.
    Feathers/body surface -
    Oil on feathers, oil around the vent.
  • Gastrointestinal Tract - May contain oil. May contain little or no food. Mucosa may be inflamed, ulcerated and haemorrhagic.
  • Respiratory -
    • May be oil in the trachea and/or lungs, pulmonary oedema and/or hyperaemia and haemorrhage, oil-aspiration pneumonia. May be water in lungs and airsacs if death has occurred by drowning.
    • In oil-killed ducks, 61% had gross lesions described as pneumonia; four of the five were histologically confirmed as lipid pneumonia. (J40.30.w2)
  • Liver - hepatic lipidosis.
    •  
  • Adrenals - May be enlarged
  • Salt glands - May be swollen.
  • Dehydration and renal damage may result in visceral Gout.

(J1.32.w6, J40.30.w2, B15, B23.38.w2, B36.42.w42, P4.1990.w1, P10.28.w1)

Gross:

  • Gastro-intestinal tract:
    • Haemorrhagic enteritis in 7/12 ruddy ducks Oxyura jamaicensis - Ruddy duck  following oiling with #6 fuel oil. (P14.1.w11)
      • Stomach: sometimes contained clotted blood. (P14.1.w11)
      • Serosal service of the intestines diffusely hyperaemic, mucosa congested and thickened, sometimes contained clotted blood. (P14.1.w11)
    • Gastrointestinal tract irritation, with intestinal wall hyperaemia and occult blood in the intestines. Severe irritation resulted from ingestion of either fuel oil or diesel oil at 1 ml/kg or higher (J40.30.w2)
  • Kidneys: Accumulation of urate tophi. (P14.1.w11)
  • Serosal surfaces of the liver, pericardial sac, air sac: accumulations of uric acid crystals (urate tophi), i.e. visceral gout. (P14.1.w11)
  • Adrenals:
    • Adrenal glands enlarged and haemorrhagic in 4/12 individuals.  (P14.1.w11)
    • In ducks experimentally given various oils by stomach tube, adrenal enlargement was evident. (J40.30.w2)
  • Lungs: marked hyperaemia in ducks with lipid pneumonia following experimental dosing with oil. (J40.30.w2)

Histopathology:

  • GIT: 
    • In the intestines, mucosal vessel congestion, extravasation into the lamina propria and through the disrupted epithelium. (P14.1.w11)
    • Hyperaemia of the intestinal wall; no areas of specific haemorrhage into the lumen were found. In ducks experimentally dosed with various oils by stomach tube. (J40.30.w2)
    • Hyperaemia of the intestines and occult blood in the lumen were found in wild oil-killed ducks. (J40.30.w2)
  • Lungs: diffuse congestion and severe haemorrhage into air spaces in 1/123 ducks. (P14.1.w11)
    • Haemosiderosis was found in the lungs of some wild seaducks (Melanitta fusca - White-winged scoter, Melanitta nigra - Black scoter and Clangula hyemalis - Long-tailed duck) which died during rehabilitation following oiling with Bunker C oil. (J1.32.w6)
    • In ducks experimentally given oil by stomach tube, lipid pneumonia with marked hyperaemia of the affected areas of the lung, walls of air capillaries in the parabronchi thickened by intense inflammation with lymphocytes and connective tissue proliferation, with the air capillaries often occluded by the thickening; only occasional giant cells were present. Oil droplets were present lodged in the parabronchi, with haemorrhagic inflammation in such areas; the such droplets were often visible by the outline left by erythrocytes, lymphocytes and neutrophils incorporated into the droplet. Haemorrhagic serous exudate (and a lack of normal parabronchial tissue) was found around the droplets and the area was often walled off by connective tissue. (J40.30.w2)
  • Haemoperitoneum in 2/12 individuals. (P14.1.w11)
  • Liver: congestion and bile stasis; occasional foci of hepatocyte necrosis. (P14.1.w11)
  • Spleen:
  • Heart: focal myocardial degeneration in 2/12 birds. (P14.1.w11)
  • Kidney:
  • Adrenals:
    • In ducks experimentally given various oils by stomach tube, adrenal enlargement was found to be due to hyperplasia of cortical tissue, with minimal increases in medullary tissue. (J40.30.w2)
      • Gross enlargement of the adrenals was also evident in about 75% of examined wild oil-killed ducks. (J40.30.w2)
  • Pancreas:
    • Reduction in zymogen granules in birds sacrificed 48 hours after being given various petroleum oils by stomach tube. Granules were absent in ducks given 6 ml/kg of diesel oil and the pancreas parenchyma showed cloudy degeneration and appeared to be in the early stages of acinar atrophy. (J40.30.w2)
MAMMALS

Gross lesions:

  • Oil may be visible externally or found on examination of the inside of the ears, the anus, the trachea or the gastro-intestinal tract. (B20.13.w10)
  • In a Tursiops truncatus - Bottlenose dolphin found dead following an oil spill, the blow-hole was plugged with oil. It was not proved that the oil had been the cause of death. (J320.8.w1)
  • In five Lutra lutra - European otter found dead following an oil spill, the pelage was oiled and the main gross internal abnormalities were in the gastrointestinal tract, with a haemorrhagic gastroenteropathy: in the stomach, the presence of blood and mucosal hyperaemia, in the small intestines presence of blood, mucus and oil in the lumen, and mucosal haemorrhages. In two animals gastric contents were present in the trachea and there was a tracheitis. (J17.20.w1)
  • Ocular membranes may be inflamed. (B20.13.w10)
  • In Enhydra lutris - Sea otters found dead and with external oil present, during the Exxon Valdez oil spill, interstitial pulmonary pneumonia was noted in 66%, while gastric erosion and haemorrhage were noted in 55%; 42% of otters had both lesions. (P14.3.w27)
  • Inhalation of volatile hydrocarbons may result in mucous membrane inflammation, pulmonary oedema, pulmonary haemorrhage and pneumonia. (P24.327.w4)
  • In harbour seals (Phoca vitulina - Common seal) following oil exposure in Prince William Sound (Exxon Valdez spill), gross lesions included variable oil on the pelage, and conjunctivitis. (B377.17.w17) 
  • In both grey seals (Halichoerus grypus - Grey seal) and harbour seals (Phoca vitulina - Common seal), found dead stranded along the coast of France, oil has been found grossly present in the intestines. (B368.4.w4)
  • In polar bears Ursus maritimus (Ursus - (Genus)) exposed to oil by being placed in an oil-covered pool, and which then ingested oil while grooming, lesions, which were thought to be associated with the combination of oil toxicity and stress, included kidney tubule degeneration, low-grade hepatic lesions, depressed lymphoid tissue activity and mycotic gastro-intestinal ulcers. (B368.10.w10)
  • In domestic cattle calves given "sweet" (low sulphur) crude oil, "sour" (high sulphur) or kerosine, by stomach tube:
    • Respiratory: the main pathological finding was aspiration (foreign body) pneumonia, often with localised pleuritis, and with hydrothorax in severe, acute cases. Pulmonary lesions, usually bilateral, involved the caudoventral apical, cardiac, cranioventral, diaphragmatic and intermediate lobes; affected areas were dark purple and consolidated, with, in those animals which had survived several days, multiple abscesses. Oil was only visible grossly in lung tissue of two calves. Unilateral gangrenous pneumonia was present in one calf given sour crude oil and a large encapsulated pulmonary abscess was found in an individual given sweet crude. In the ventral tracheal mucosa of four calves given sweet crude oil or kerosine either raised yellow-green plaques of about 1 cm diameter, or extensive ulceration with a covering green pseudomembrane were noted. 
    • Gastrointestinal: in the gastrointestinal tract, oil was visible in the rumen of calves dying within four days of being given oil, but in only one of nine calves dying after six days or more. Those given sour crude were noted to have black staining of the mucosa of the rumen. In one calf given kerosine there were multiple linear ulcerations along the length of the oesophagus (reflux oesophagitis) and severe dermatitis below the anus. (J4.162.w1)

Histopathology:

  • Centrilobular hepatic necrosis and diffuse hepatic lipidosis were recorded more commonly in oiled Enhydra lutris - Sea otters than in those not exposed to oil. Periportal hepatic lipidosis was seen in those which died after a period of two weeks or more. (B20.13.w10)
  • Renal tubular lipidosis was seen in 25% of otters dying within two weeks of the spill and in 60% of those dying after a longer period. (B20.13.w10)
  • Lipidosis and centrilobular necrosis may occur due to hypoglycaemia and shock secondary to hypothermia resultant from oiling. (B20.13.w10)
  • In Enhydra lutris - Sea otters during the Exxon Valdez oil spill and dying following admission to rehabilitation centres, the main lesions were interstitial pneumonia, gastric erosion and haemorrhage, centrilobular hepatic necrosis, periportal to diffuse hepatic lipidosis and renal tubular lipidosis. Interstitial pneumonia and hepatic and renal lipidosis were also found in oiled otters found dead. (J26.30.w2, P1.1991.w2, P14.3.w28)
    • Respiratory: interstitial pulmonary pneumonia was noted in 73% of 15 heavily contaminated, 45% of moderately contaminated and 15% of lightly contaminated Enhydra lutris - Sea otters. Lesions were described as expanded areas of clear space, with rounded contours, within the interlobular septa. Additionally, on occasion, adjacent parenchyma was compressed or atelectic. This lesion was definitely associated with exposure to crude oil, but the pathogenesis has not been determined. (J26.30.w2, P14.3.w28)
      • Pleural, mediastinal, pericardial and/or subcutaneous emphysema were seen also in many animals with interstitial pneumonia. (P1.1991.w2)
      • Interstitial emphysema was also seen in the lungs of one of five otters examined histologically having been found dead shortly after the spill. (J26.30.w2, P1.1991.w2)
      • Interstitial pneumonia was particularly common in heavily or moderately oiled otters which died within eight days of arrival at the rehabilitation centre. (J26.30.w2)
    • Gastro-intestinal: gastric erosions were present in two of 14 (14%) heavily contaminated, 7/9 (78%) moderate and 4/17 (24%) lightly contaminated Enhydra lutris - Sea otters. The erosions were described as discrete areas of coagulative necrosis, 1-3 mm diameter, affecting the superficial to mid-level gastric mucosa, with variable amounts of haemorrhage and dark brown pigment (acid digested blood) in the necrotic areas. Neutrophils were sometimes found in small numbers along the erosion margins. This lesion is considered to be associated with stress. (J26.30.w2, P1.1991.w2, P14.3.w28)
      • Both oil toxicity and stress are believed to have contributed to gastrointestinal haemorrhage (resulting in melaena) and chronic gastric erosion. (B20.13.w10)
    • Hepatic: 
      • Hepatic lipidosis was present in 8/16 heavily oiled, 5/12 moderate and 1/19 lightly oiled Enhydra lutris - Sea otters. The lesions, found in the cytoplasm of periportal hepatocytes (and in severely affected animals also in midzonal and centrilobular hepatocytes) consisted of multiple (occasionally single), variable-size, round, sharply delineated unstained vacuoles, which stained red with oil red O stain, indicating the presence of lipid. This lesion may be associated with mobilisation of stored fat (due to increased energy demand in oiled otters) or may be a direct or indirect metabolite-associated toxic effect of oil. (J26.30.w2, P14.3.w28)
        • Hepatic lipidosis was also seen in three (one male, two female) of five Enhydra lutris - Sea otters examined histologically having been found dead shortly after the spill. (J26.30.w2, P1.1991.w2)
      • Centrilobular necrosis was present in 4/16 heavily, 3/12 moderately and 4/19 lightly oiled otters. The lesions were described as coagulative necrosis, with pyknosis, karyorhexis, karyolysis and eosinophilia of cytoplasm; basic cell shape was preserved. (J26.30.w2, P14.3.w28)  Anaemia may have contributed to the development of this lesion. (J26.30.w2)
      • Focally extensive or multifocal hepatic necrosis was seen in 7/16 heavily, 0/12 moderately and 3/19 lightly oiled Enhydra lutris - Sea otters as well as in 2/6 unoiled individuals. (P1.1991.w2)
    • Renal: Renal lipidosis was present in 10/42 Enhydra lutris - Sea otters; it was less common than hepatic lipidosis and was never found without hepatic lipidosis also being present in the affected individuals. Affected cells were found in the proximal and distal tubular epithelium, and consisted of single or multiple vacuoles, variable-size, round, sharply delineated unstained vacuoles, which stained red with oil red O stain, indicating the presence of lipid. As with hepatic lipidosis, this lesion may be associated with mobilisation of stored fat (due to increased energy demand in oiled otters) or may be a direct or indirect metabolite-associated toxic effect of oil. (J26.30.w2, P14.3.w28)
      • All the sea otters with renal lipidosis which died during rehabilitation were female. (J26.30.w2)
      • Renal lipidosis was also seen in three of five Enhydra lutris - Sea otters examined histologically having been found dead shortly after the spill, including one male and two females. (P1.1991.w2)
  • In Lutra lutra - European otter found dead following an oil spill, histological changes were notable particularly in the lungs, which showed congestion and oedema, with areas of collapse in one animal. (J17.20.w1)
  • In harbour seals (Phoca vitulina - Common seal) found dead following the Exxon Valdez oil spill in Prince William Sound, Alaska, the main lesions were found in the brain stem, particularly the thalamus, medulla oblongata and the spinal cord, and consisted of neuronal necrosis, axonal degeneration and intramyelinic oedema. (P20.1992.w4)
  • In harbour seals (Phoca vitulina - Common seal) following oil exposure in Prince William Sound (Exxon Valdez spill), the main neurological lesions were "intramyelinic oedema, neuronal swelling, neuronal necrosis, and axonal swelling and degeneration within the midbrain." It was considered probably that the lesions followed inhalation of short-chain aromatic hydrocarbons. Other lesions occurred in the eyes (lymphoplastic conjunctivitis), skin (acanthosis and hyperkeratosis) and liver (hepatocellular swelling and bile inspissation). (B377.17.w17)
  • When three polar bears Ursus maritimus (Ursus - (Genus)) exposed to oil by being placed in an oil-covered pool, one died and a second was euthanised. Lesions were mainly associated with terminal severe dehydration and uraemia and included hyperkeratosis, allopecia, histopathological lesions of the digestive tract, liver, brain, bone marrow and lymphoid issue, and adrenal changes consisting of a hyperplastic cortex and degeneration of the zona arcuata. (B378.7.w7)
REPTILES Gross lesions:
  • Tar balls may be found in the stomach of marine turtles. (B369.w6)

Histopathology:

Skin and exposed mucous membranes

  • Caretta caretta - Loggerhead turtles experimentally exposed to oil showed gross and histological skin lesions consistent with a contact/irritant dermatitis. Dysplastic change was sometimes marked. Most changes had resolved by 10 days after cessation of exposure to the oil. (P14.3.w29)
    • Epidermis: "moderate to extensive acanthosis and hyperkeratosis with moderate multifocal keratinocyte dysplasia and necrosis." Cellular bridges, cell uniformity and cellular architectural orientation were lost. Additionally there was infiltration of the epidermis by heterophilic granulocytes, mainly below the stratum corneum. (P14.3.w29)
    • Dermis: moderate to severe diffuse oedema, with infiltration of heterophilic granulocytes, occasional plasma cells. Mild multifocal superficial haemorrhage. (P14.3.w29)
    • Note: by 10-13 days after oiling, biopsies still showed moderate acanthosis and hyperkeratosis of the skin, and marked exfoliation of the outer keratinised layer. (P14.3.w29)

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Human Health Considerations

  • Direct contact with petroleum, handling oiled wildlife, and activities associated with the cleanup are all potentially hazardous to humans.
  • Toxic effects of petroleum include contact dermatitis, increased skin cancer risk, eye irritation, and problems associated with inhaling volatile components of petroleum products.
  • Acute exposure to concentrated gasoline vapours containing aromatic petroleum compounds, including benzene, may cause dizziness, headaches, incoordination, anaesthesia, coma and even respiratory arrest. (P14.3.w12)
  • N.B. petroleum products may be contaminated with other chemicals including polychlorinated biphenyls (PCBs) and organophosphates.

(B20.13.w10, B36.42.w42, P14.3.w12)

  • Care should be taken to avoid being injured by birds with sharp bills; this is not a major problem with waterfowl, but can be problematic with other species which may be affected by oil.
  • Protective clothing should be worn while rescuing and caring for oiled wildlife, and care should be taken on slippery rocks. Hypothermia or hyperthermia (depending on environmental conditions), falls and drowning are common and serious hazards when rescuing oiled birds.

(B20.13.w10, B36.42.w42)

Further information is provided in: Human Health and Zoonoses in Oiled Wildlife Response

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Susceptibility / Transmission

General information on Susceptibility / Transmission

BIRDS Aquatic birds are highly susceptible to oiling because they live at the interface between water and land/sky, swimming in, diving through and resting on the water surface, and because they are highly dependent for insulation, water-repellency and flight on maintenance of the structure and function of their feathers, which is greatly disrupted by oil. (P14.2.w6)
  • Birds most commonly come into contact with oil by landing on or swimming through slicks on water, or on land on beaches, shores, reed beds and swamps. (P24.327.w4)
  • Seabirds are particularly susceptible to oiling from spills. (B36.42.w42)
  • Species which spend most of their time on the water or diving into the water are most vulnerable to oil floating on the water. This includes birds such as alcids, seaducks and penguins. (D214.1.w1, P14.1.w7)
  • Bird species which congregate at sea or on shorelines in large numbers for feeding, breeding or moulting are highly vulnerable to oil. (D214.1.w1, W469.Oct03.w2)
  • Species such as ducks, grebes, cormorants and penguins, which spend a large proportion of their time in the water, are most likely to become oiled. Terns, pelicans, gulls and pelagic sea birds, which spend more time in the air or on land, are most likely to come into contact with oil while feeding. (P24.327.w4)
  • Diving birds such as grebes, loons and mergansers, as well as sea ducks and other species which tend to concentrate on wintering grounds, are vulnerable to oiling, particularly during the winter. Eiders are vulnerable year round. (B36.42.w42)
  • Species which feed and breed along the shore, such as wading birds, kingfishers and some raptors, may also come into contact with oil. (P24.327.w4)
  • Auks tend to dive and surface repeatedly in a slick and therefore become coated with oil, while gulls do not dive but fly off with only ventral oiling. (P3.1961-1970.w1)
  • Large wading birds such as herons and bitterns, also gulls, are less susceptible than species which spend more of their time on the water. (B36.42.w42)
  • Species which are not generally associated with water may become oiled on occasion, for example when landing on a thick layer of oil which appears solid. (P24.327.w4)
  • As well as becoming coated with oil, birds may inhale volatile components. (D183.w3)
  • Note: while there is no doubt that some birds, having been contaminated with oil, then successfully clean themselves, live and breed apparently normally, self-cleaning takes longer for a bird with a large patch of oil than for one with a small patch of oil. Oiled birds must survive long enough to remove the oil from their feathers, restore the micro-structure and water repellency of the feathers, and survive the toxic effects of oil ingested while preening; oiled birds are under greater stress during cold and bad weather. Whether or not a bird survives is probably affected by the time of year, food availability and weather conditions. (J41.66.w1)
  • Experimentally, it has been shown that once water penetration of the plumage has occurred it will continue, even if the bird preens its plumage, unless the bird leaves the water for long enough for the feathers to dry out fully. (J318.24.w1)
  • Thermal conductance through the plumage is higher when a bird is in water than when it is in air. Therefore even with intact, properly water repellent plumage, waterbirds which live at medium to high latitudes will need a higher resting metabolic rate for most of the year simply to maintain body temperature while sitting on water. (J318.24.w1)
  • Note: Oil may also have indirect effects: birds may be forced to leave an area due to oil making normal food supplies unavailable. (J320.8.w1)
  • A small amount of oiling may reduce insulation and water-repellency, leading to increased heat loss, shivering and, if adequate food is not available, use of body reserves. This decreases the bird's average density, leading to reduced dive length and depth, making it more difficult for diving birds to get food, leading to increased use of energy reserves and a "spiral" leading to death from exposure and starvation. (J313.11.w2)
  • On a population level, populations already under stress may be further jeopardized by loss of adults or young birds due to either heavy oiling or light oiling acting synergistically with environmental stressors. (J313.11.w2)
WATERFOWL  Transmission:
  • Oiling occurs when oil is released into the environment. Oil may be ingested when birds preen, and in contaminated water and food. Oil may contaminate eggs when oiled birds return to the nest.

Susceptibility:

  • All species may be susceptible if oil is spilt/discharged into their local environment. Waterfowl are among the species considered highly susceptible to oiling. Sea ducks are highly susceptible to oil spills in the marine environment. The greatest effects may be seen on species which are gregarious (forming large aggregations), spend most of their time on the water, dive into the water to find food or to avoid disturbance, and are found near shipping lanes.
  • Mute swans are also susceptible, due to residing in places such as navigable rivers in industrial areas. (J3.70.w1)

(B15, B18, B20.13.w10, B36.42.w42, J3.70.w1, P14.5.w2)

CRANES
  • Data from Grus canadensis - Sandhill crane experimentally dosed with Prudhoe Bay crude oil, indicate that crude oil is not severely toxic to cranes; they are more likely to be adversely affected by oiling of the feathers than by oil ingestion. (J40.46.w1)
MAMMALS

Aquatic and semi-aquatic mammals:

  • Aquatic mammals may not avoid oil. (J17.20.w1)
  • Aquatic mammal species which rely on their fur for insulation are more vulnerable, and more likely to show mortality following oil exposure, than those which rely primarily on blubber for insulation. This includes otters, newborn Phocidae - Seals (Family) seal pups, fur seals (Otariidae - Sea lions (Family)) and polar bears (Ursus maritimus - Ursidae - Bears (Family)). (B335.15.w15, B379.22.w22, P14.2.w1, P14.2.w5)
    • Polar bears (Ursus maritimus - Ursidae - Bears (Family)) rely on their thick coat as well as their subcutaneous fat for insulation. Thermal conductance through wet oiled pelts has been shown to be five to six time faster than through dry pelts. (B368.10.w10)
  • Aquatic mammals may inhale volatile oil components at the air/water interface. (B377.15.w15, B377.17.w17)
  • Seals and cetaceans are able to metabolise petroleum oils and show rapid renal clearance, which minimises the toxic effects of ingested oil on these species. (P14.2.w1)
River and Sea Otters
  • Otters may ingest oil while grooming themselves after becoming contaminated with oil, or by predating oiled seabirds. (B368.8.w8, J17.20.w1)
  • Otters, in grooming once oiled, may spread the oil deeper into the fur, thus exacerbating the problem. (J30.66.w1)
  • Oiled otters may groom excessively while attempting to remove oil, reducing the time available for them to catch food, at a time when more food is required due to the increased energy demands associated with the loss of insulation. It is probable that survival is affected by the degree of oiling, which will have an effect on the amount of grooming and the increased metabolic rate and therefore increased food required. (B368.8.w8)
  • Enhydra lutris - Sea otters are at particular risk because they tend to stay in a given area, even if it becomes oiled. (B368.8.w8)
Ursus maritimus - Polar bears
  • Experimentally, it has been shown that polar bears can detect oil on water and will avoid oiled water if possible, however they might still become oiled in some circumstances, for example emerging through oil after chasing a seal. (B368.10.w10)
  • Polar bears show no obvious aversion to the taste of oil, and might ingest oil by scavenging oiled seals or birds. (B368.10.w10)
  • Large quantities of ingested oil may cause renal failure and blood disorders and be lethal to polar bears. (P14.2.w1)
  • Stressed bears (e.g. in conditions of low food availability) are likely to be more susceptible to the toxic effects of oil. (B368.10.w10)

Cetaceans

  • Experimentally, it has been shown that Tursiops truncatus - Bottlenose dolphins can detect oil and prefer to avoid it. However, various cetaceans have been observed swimming in oiled waters. (B368.6.w6, B378.7.w7)
  • In general it appears that exposure to petroleum may have little effect on cetaceans. (B378.7.w7)

Pinnipeds

  • It is not clear whether pinnipeds detect and avoid oil. In many situations it has been observed that they appear to be indifferent to the presence of oil and have been observed swimming through oil and hauling out onto oiled shores. They may avoid oil in some circumstances: harbour seals (Phoca vitulina - Common seal) temporarily left Yell Sound when oil from the Esso Bernicia escaped from containment booms, and returned after most of the oil had beached. (B368.4.w4)
  • Experimentally, it has been shown that seals (harp seals Phoca groenlandicus and ringed seals Phoca hispida (Phoca - (Genus))) are able to tolerate relatively small quantities of ingested oil, such as they might realistically ingest when feeding in a contaminated area. Ingestion of oil due to preening is unlikely since this is not a common activity in these animals. (B368.4.w4)
  • Susceptibility to the toxic effects of inhaled petroleum vapours may be increased in pinnipeds under stress, for example due to parasitism. (B368.4.w4)
  • Among pinnipeds, those at highest risk are those covered by fresh oil, females with pups and oiled fur seals. (P14.2.w5)
  • Neonates and immature pinnipeds are probably more susceptible to oil than are adults due to: (B377.13.w13)
    • Less developed musculoskeletal system reducing the ability of pups to swim through or out of oiled waters;
    • A thinner blubber layer than adults, providing less thermal insulation, therefore increased reliance on the fur as a thermal barrier;
    • Risk of ingestion of oil by pups while suckling.

    (B377.13.w13)

  • Oil on unweaned seal pups may disguise the smell of the pup and thus interfere with maternal recognition of the pup; this may result in abandonment. (P24.327.w4)

Semi-aquatic rodents:

  • Rodents which rely on their fur for insulation are also susceptible if their habitats become oiled. For example it has been shown that muskrats Ondatra zibethica (Muridae - Rats, mice, voles, gerbils etc. (Family)) have a greatly increased thermal conductance, heat production and food requirement when oiled. (J30.52.w1)

Other mammal species:

  • Bats may become oiled by flying into oil left in places such as garages. (B284.9.w9, V.w47)
  • Hedgehogs may become oiled by falling into containers of oil left open in garages or workshops. (B259.w10, V.w47)
  • Sheep have been found dead with oesophageal and gastric ulceration after being seen eating oil-contaminated seaweed. (J17.20.w1)

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Disease has been reported in either the wild or in captivity in:

Non-petroleum oils:

Examples of oiling incidents involving non-petroleum oils include the following:

  • Cape gannets, Cape cormorants and Jackass penguins near Bird Island, Lamberts Bay, South Africa, following a spill of fish oil mixtures in 1974. (N15.62.w1)
  • Thousands of seabirds, mainly guillemots and razorbills. Birds which washed ashore were covered with oil, emaciated, aggressive, with bloody droppings and leaky plumage. Affected individuals had liver damage and lung infections. This spill involved nonylphenol and vegetable oils, in the Netherlands, December 1988-March 1989). (N15.62.w1)
  • Three small rapeseed oil spills in Vancouver Harbour, 1974-1978, killed about 500 birds in total. (N15.62.w1)
  • Following a spill of about 400 gallons of rapeseed oil in 1989, 88 birds of 14 species were picked up, of which half were already dead and half of the remainder later died. About 300 Barrow's goldeneyes were seen, oiled, crowded onto two islands where they remained for two days; their eventual fate was not known. (N15.62.w1)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

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Disease has been specifically reported in Free-ranging populations of:

Non-petroleum oils:

Examples of oiling incidents involving non-petroleum oils include the following

  • Cape gannets, Cape cormorants and Jackass penguins near Bird Island, Lamberts Bay, South Africa, following a spill of fish oil mixtures in 1974. (N15.62.w1)
  • Thousands of seabirds, mainly guillemots and razorbills. Birds which washed ashore were covered with oil, emaciated, aggressive, with bloody droppings and leaky plumage. Affected individuals had liver damage and lung infections. This spill involved nonylphenol and vegetable oils, in the Netherlands, December 1988-March 1989). (N15.62.w1)
  • Three small rapeseed oil spills in Vancouver Harbour, 1974-1978, killed about 500 birds in total. (N15.62.w1)
  • Following a spill of about 400 gallons of rapeseed oil in 1989, 88 birds of 14 species were picked up, of which half were already dead and half of the remainder later died. About 300 Barrow's goldeneyes were seen, oiled, crowded onto two islands where they remained for two days; their eventual fate was not known. (N15.62.w1)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

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Environment/Geography

General Information on Environmental Factors/Events and Seasonality

  • Large-scale oil spills occur most frequently on routes of oil tankers and other large ships, along oil pipelines and at sites of oil wells and oil refineries. 
  • Major oil spills occur most frequently related to winter storms, with January to March being the peak oil spill season.
  • Considerable quantities of oil are released as intentional discharges from transport and refining operations, industrial discharges etc. as well as from urban runoff and the disposal of used lubricant oil and other waste oils. Small scale releases may occur almost anywhere, for example at out-falls from water treatment plants, storm drains etc., around marinas and ports (discharges from boating and shipping activities) and in rivers and streams from boats etc.
  • Winter oil spills at sea are most likely to affect waterfowl species which concentrate on marine wintering areas (e.g. scoters, scaups, long-tailed ducks, canvasbacks, mergansers, also loons and grebes). Spills in the marine environment at any time of the year may affect eiders.
  • Small scale spills and releases of oil may occur all year around. 

(J7.30.w6, B20.13.w10, B36.42.w42, P62.1.w1)

  • Whether or not a bird survives is probably affected by the time of year, food availability and weather conditions. (J41.66.w1)
    • Individuals in severe environmental conditions (e.g. in the Arctic) may be fatally affected by even small quantities of oiling, due to synergism with other stressors. (J313.11.w2)
    • Even small areas of oiling may be fatal for birds in cold water. (J320.8.w1)
    • Minor oiling may act synergistically with stresses of severe environmental conditions and lead to death after a period of time. (J313.11.w2)
    • Toxicity may be exacerbated in individuals under stress including cold stress and overcrowding. (J40.30.w2)
    • Oiled birds will succumb faster if they do not have access to adequate food. (J320.8.w1)

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Regions / Countries where the Infectious Agent or Disease has been recorded

Worldwide. Large-scale oil spills occur most frequently on routes of oil tankers and other large ships, along oil pipelines and at sites of oil wells and oil refineries. Small scale releases may occur almost anywhere, e.g. at out-falls from water treatment plants, storm drains etc., improper disposal of waste oil, and in rivers and streams from boats etc.

(B20.13.w10, B36.42.w42)

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Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

Worldwide. Large-scale oil spills occur most frequently on routes of oil tankers and other large ships, along oil pipelines and at sites of oil wells and oil refineries. Small scale releases may occur almost anywhere, e.g. at out-falls from water treatment plants, storm drains etc., improper disposal of waste oil, and in rivers and streams from boats etc.

(B20.13.w10, B36.42.w42)

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General Investigation / Diagnosis

General Information on Investigation / Diagnosis

BIRDS
  • Gross oiling is easy to diagnose but proving oil intoxication as the cause of death is more complex.
    • Diagnosis of oiling as the cause of death of an individual involves both demonstration of exposure to oil and ruling out other possible causes of illness or death. (B20.13.w10)
    • Diagnosis may be based on circumstances leading to a reasonable suspicion of oiling, lack of signs or lesions indicating another cause of death, plus or minus lesions consistent with exposure to oil. (B20.13.w10)
  • N.B. 1) Oiling may not be clearly visible on the affected individuals by the time of death from e.g. starvation and hypothermia.
  • N.B. 2) Birds found dead which are externally contaminated with oil may have become oiled after death.
    • Detection of the presence of petroleum oil on feathers or pelage does not necessarily show that oiling was the cause of death. (B20.13.w10)
  • History and records of environmental contamination are important as well as clinical signs and post mortem examination findings.
  • Useful findings include obvious oil in the environment, visible oiling and matting of feathers. Oil may be smelled on the feathers. Light, transparent oils may be detected by the appearance of an oil sheen if feathers are placed on water. An ELISA can detect the polycyclic aromatic hydrocarbons (PAHs) in oil on feathers.
  • Whole carcasses should be submitted to diagnostic laboratories together with good background information and field observations.
  • No lesions, either gross or histological, are pathognomonic of oil toxicity.
  • Methods of chemical detection which are useful for identification of petroleum products in the environment are not necessarily useful for identification of petroleum residues in animal tissues. (B20.13.w10)
  • Blood samples may reveal Heinz-body anaemia.

(B15, B20.13.w10, B36.42.w42).

WATERFOWL
  • Gross oiling is easy to diagnose but proving oil intoxication as the cause of death is more complex.
  • N.B. 1) Oiling may not be clearly visible on the affected individuals by the time of death from e.g. starvation and hypothermia.
  • N.B. 2) Birds found dead which are externally contaminated with oil may have become oiled after death.
  • History and records of environmental contamination are important as well as clinical signs and post mortem examination findings.
  • Useful findings include obvious oil in the environment, visible oiling and matting of feathers. Oil may be smelled on the feathers. Light, transparent oils may be detected by the appearance of an oil sheen if feathers are placed on water. An ELISA can detect the polycyclic aromatic hydrocarbons (PAHs) in oil on feathers.
  • Whole carcasses should be submitted to diagnostic laboratories together with good background information and field observations.
  • Blood samples may reveal Heinz-body anaemia.

(B15, B20.13.w10, B36.42.w42).

MAMMALS
  • It can be difficult to determine whether an individual marine mammal, having a dark, shiny pelt, is or is not oiled. Field assays may be used to detect petroleum products on the pelt so that individuals which are not oiled can be quickly released or relocated rather than cleaned and rehabilitated. (D208.4.w4)
  • An indication of internal exposure to oil may be determined from the level of petroleum hydrocarbons in the blood, such as the total paraffinic hydrocarbons (TPH), from a sample taken within 48 hours of exposure to oil. In animals not exposed to oil, the level of these compounds in blood should be less than 1 ppm. In Enhydra lutris - Sea otters oiled by the Exxon Valdez oil spill, there was a correlation between high levels of total paraffinic hydrocarbons and severity of emphysema (all individuals with subcutaneous emphysema had levels of greater than 224 ppm; sea otters without emphysema had a mean level of 65 +/- 57 (SE) ppm), and between high levels of total paraffinic hydrocarbons and failure to survive: the mean level for otters surviving at least 20 days was 112 +/- 92 (SD) ppm. (B335.4.w4) Note: the TPH concentration provides a relative index of toxicosis, but the lethal thresholds indicated by TPH will vary depending on the type of oil, duration of contact with the oil and the oiled species. (B335.4.w4)

Secondary problems in oiled mammals may be associated with a variety of causes. Distinguishing the underlying cause is important for therapy.

Respiratory Distress:

  • Respiratory distress may be seen due to damage, particularly caused by volatile agents, to the mucous membranes of the airways. (D208.5.w5) 
    • In Enhydra lutris - Sea otters, respiratory distress may be seen associated with lung damage and interstitial emphysema. In these animals, subcutaneous air may be present causing crepitation in the neck and axillary regions. The diagnosis and its extent may be confirmed using radiography, ultrasound or bronchoscopy. D208.5.w5)
  • Other causes of respiratory distress in oiled mammals include: (D208.5.w5)
    • Sinus infections and pneumonias secondary to poor nutrition, stress and immunocompromise;
    • Aspiration pneumonia, due to poor stomach tubing technique, vomiting or regurgitation.

    (D208.5.w5)

Seizures:

  • Seizures seen in oiled animals may be associated with hypoglycaemia, hypothermia, hyperthermia, hepatic encephalopathy, electrolyte imbalances, dehydration, sepsis, petroleum hydrocarbon exposure, adverse reaction to anaesthetics such as fentanyl), or trauma, as well as concurrent disease. (B335.5.w5, D208.5.w5)

Cyanosis:

  • Cyanosis may be due to respiratory distress or hypothermia, both of which may be seen as complications of oiling. It is important to distinguish between these causes in order to initiate appropriate therapy. (D208.5.w5)

Vomiting:

  • Causes of vomiting in oiled mammals include: (D208.5.w5)
    • Irritation of the mucous membrane of the stomach by oil ;
    • Direct stimulation of the vomiting centre in the brain;
    • Gastrointestinal ulceration (due to petroleum ingestion, stress, gastrointestinal parasites or (in Enhydra lutris - Sea otters) lack of food);
    • Gastrointestinal foreign bodies;
    • Gastric impaction/obstruction;
      • This may be caused by formula thickening in the stomach;
      • Gastric impaction is more common in individuals which are inadequately hydrated.
    • Maldigestion;
    • Mechanical irritation of the oesophagus/stomach by stiff feeding tubes or tubes inserted with insufficient care;
    • Overloading with excess food or food given too frequently.

    (D208.5.w5)

Related Techniques
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Similar Diseases (Differential Diagnosis)

BIRDS Loss of waterproofing may also be seen following contact with detergent in the absence of oil. (N16.66.w1)

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Treatment and Control

Specific Medical Treatment

See: Oiled Wildlife Admission and Stabilisation
BIRDS
  • Areas of skin with chemical burns should be cleaned thoroughly using dilute chlorhexidine solution, followed by application of a water-soluble antibiotic ointment. (J29.8.w1)
  • Activated charcoal or other protectants to treat gastrointestinal irritation. (B20.13.w10)
  • Vitamin E and selenium may be useful to help combat anti-oxidant effects. (P14.2.w6)
  • To facilitate red blood cell replacement, reversing anaemia: iron dextran, vitamin B complex. (D16)
  • See: Oiled Wildlife Admission and Stabilisation
WATERFOWL
  • Iron dextran (10 mg/km intramuscularly) weekly if anaemic.
  • Chloramphenicol eye drops three or four times daily for corneal ulcers (from physical trauma or chemical irritation of oil) N.B. avoid petroleum-based ointments (P4.1990.w1).
  • Antibiotics (e.g. enrofloxacin 10 mg/kg intramuscular or oral, daily) may be used as prophylaxis if a specific risk of bacterial infections such as bacterial enteritis has been identified. N.B. Antibiotic administration may increase the risk of fungal diseases (e.g. Aspergillosis) and particular care should be given if considering their use in Aspergillosis-prone species such as eiders.
  • Antifungal prophylaxis particularly for Aspergillosis-prone species such as eiders: Itraconazole (Sporanox, Janssen Pharmaceuticals, Piscataway, New Jersey, USA) 10mg/kg orally twice daily initially, daily once birds are washed and on pools. N.B. balance with increased stress of catching and treatment, which in itself may predispose to Aspergillosis.
  • Antifungal treatment may be required for Candidiasis or Aspergillosis.
  • Anthelmintics may be useful to reduce parasite burdens and therefore facilitate weight gain and improve general health.

(B11.35.w3, D6, P4.1990.w1, P14.5.w5)

MAMMALS Treatment of seizures:
  • Determine the underlying cause of the seizure and correct the cause. (D208.5.w5)
  • For persistent or recurrent seizures, particularly without an underlying metabolic cause, use benzodiazepines, barbiturates or other such agents as required. (D208.5.w5)
    • For repeated/prolonged seizures, give diazepam, 0.2 mg/kg orally or 0.1 mg/kg intramuscularly. (B335.5.w5)
  • For seizures related to hepatoencephalopathy, antibiotics may be given to reduce the guts' ammonia-producing bacteria. (B335.5.w5)

Treatment of vomiting:

  • Depending on the cause, antibiotics, anthelmintics, anti-ulcer medication or drugs to speed up gastric passage may be required. (D208.5.w5)
Related Techniques
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General Nursing and Surgical Techniques

BIRDS Note: Depending on the circumstances, a single bird, a few birds or large numbers may be presented at one time. The principles of treatment and general care are the same whether many or few birds are oiled. However, large oil spills, with substantial numbers of casualties, present logistical problems in terms of space, equipment, consumables, human resources etc. Constraints on resources, particularly personnel time, mean that triage may be needed, with some, even many, birds, euthanased early in the treatment process in order to allow available resources to be concentrated on individuals with the best chance of successful rehabilitation, and those of rare or endangered species. (see: Triage and Euthanasia of Oiled Wildlife)

Initial symptomatic treatment includes:

  • Treatment for hypothermia or hyperthermia, to return individuals to normal body temperature and retain them at that temperature. (B20.13.w10)
  • Provision of good ventilation to reduce exposure to petroleum fumes and to disease agents such as Aspergillus spores. B20.13.w10)
  • Removal of oil from the eyes, nares, mouth and vent. (B20.13.w10)
  • Fluids for treatment of dehydration. (B20.13.w10)
  • Minimising stressors. (B20.13.w10)
  • Provision of nutrients.
  • Further information is provided in: Oiled Bird Admission and Stabilisation
  • Water-soluble ointment (e.g. K-Y Jelly) may be used to prevent toe webbing of species such as grebes and divers (loons) from drying out while out of water prior to being washed. (P4.1990.w1)

Oiled birds, once stabilised, require cleaning and restoration of the normal waterproof qualities of their plumage. Further information is provided in: Cleaning Oiled Wildlife

Cleaned birds require time and access to appropriate food and water for swimming in order to regain lost weight and fully restore plumage prior to release. Further information is provided in: Preparation for Release (Post-washing Care)

Warm water pools are useful in chemically burned birds, allowing exercise and preventing further feather damage. (J312.16.w1)

Nutrition:

  • Feeding efforts should take into account the fact that there may be impaired absorption from the gastro-intestinal tract in oiled birds. (P14.1.w17)
    • Tube feeding (gavage) [see: Gavage - Tubing of Birds (Techniques)] or hand- or force-feeding is likely to be required initially. (B20.13.w10)
    • Decreased absorption of water, sodium ions, glucose and amino acids has been demonstrated following oil ingestion in ducklings and young herring gulls. (P14.1.w17)
    • A diet containing simple, easily absorbed nutrients may be beneficial in the early stages of rehabilitation. (P14.1.w17)
    • Calorie-dense liquids may assist in meeting metabolic demands. (B20.13.w10)
  • Iron supplementation should be considered as oiled birds are often anaemic. (P14.1.w17)
  • Requirements for vitamin A and vitamin K may be elevated considerably following ingestion of oil. (P14.1.w17)

NOTE: SECONDARY DISEASES

A number of secondary diseases may be seen associated with oiling, including Aspiration Pneumonia, Bumblefoot, Feather Rot, Hock Lesions, Keel Lesions, Feather Rot and mechanical damage to feathers. Correct treatment and husbandry is essential to minimise the risks of such diseases developing as well as to minimise the chance of infectious diseases such as Aspergillosis, Avian Influenza, Newcastle Disease, Avian Pox, Colibacillosis, Candidiasis, Erysipelothrix Infection in Birds, Chlamydiosis - Psittacosis and various parasites. (B23.38.w2, P4.1990.w1, P24.327.w4)

  • Parasite loads may become larger and cause problems in stressed birds, while often not causing problems in health individuals in the wild. (B363.9.w9; P4.1990.w1)
  • Haemoproteus, leucocytozoon and plasmodium infections (and other haemoparasites) may have an additional effect on birds which are depressed and anaemic due to oiling. (P4.1990.w1)
WATERFOWL
  • Affected birds should be kept in a warm environment (preferably 19-21C) and as stress-free as possible. Stabilization is more important initially than washing. Initial stabilization should be initiated in the field, or at arrival at a treatment centre (if this is less than one hour away). In hot weather, appropriate shading must be provided.
  • Housing in net-bottomed cages is suggested, particularly for diving ducks (e.g. Aythyinae) and stiff-tails (Oxyura spp., e.g. ruddy duck Oxyura jamaicensis), to reduce the risk of developing keel lesions and reduce soiling with droppings. (See: Accommodation Design for Birds - Temporary / Hospital Accommodation)
  • N.B. Birds should be individually marked with leg-rings to allow individual monitoring during treatment and monitoring of survivors post-release. See: Oiled Wildlife Admission and Stabilisation, Post-Release Monitoring of Oiled Wildlife, Oiled Wildlife Records

Initial therapy:

  • Hypothermic birds (normal 100-102F) should be warmed up gently, for example using a fan heater to provide warm air, or an over head heat lamp (less effective at drying breast and abdomen), or towel-wrapped hot water bottles under the wings in larger birds N.B. monitor to avoid overheating. Warm fluids, (98-100F), slow intravenous injection, 2-3% body weight.
  • Fluid therapy should be given if necessary to treat dehydration; oiled birds may be considered to be 10% dehydrated unless clinical signs indicate otherwise. Aim to replace this 10% over 72 hours, plus 5% body weight maintenance, plus losses due to e.g. diarrhoea. Suggested suitable oral rehydration fluids (given by gavage (stomach tube) include Liquid Lectade (Pfizer Limited) (P14.5.w6), Pedialyte or lactated Ringer's solution and 2.5% dextrose (B23.38.w2); suggested amount 20 mL/kg (P14.5.w6). N.B. weak birds unable to maintain head carriage should not be given oral fluids (B23.38.w2).
  • If necessary, parenteral fluids may be given (subcutaneous, intravenous or intraosseous), e.g. 3-5% of body weight intravenous plus approximately 5% body weight subcutaneous (P4.1990.w1).
  • Adsorbent, oral, by stomach tube, e.g. 52mg/ml activated charcoal in 18 mL/kg isotonic fluids (Toxiban, Vet-A-Mix), Shenandoah, IA) (D6).
  • Enteric coating agent, e.g. bismuth subsalycylate (Pepto-Bismol), 2-5 mL/kg, after first dose of oral fluids, to reduce mucosal irritation and toxin absorption (B23.38.w2).
  • For hypoglycaemic birds (below 200 mg/dL: normal is 250-500 mg/dL), give 2.5% glucose subcutaneously (50ml/kg body weight), or oral dextrose (up to 10% solution), 50ml/kg body weight, by stomach tube (gavage).
  • Remove oil from mouth, bill and eyelids using cotton buds. If required, rinse eyes with sterile physiological saline (P14.5.w6).
  • Petroleum jelly (Vaseline, Cheseborough-Pond's Limited) smeared on the feet may be useful to prevent desiccation and cracking of skin while waterfowl are confined in cages off water prior to washing (P14.5.w6), although careful consideration should be given to the potential advantages and disadvantages before using any petroleum products.

Maintenance/stabilization prior to washing:

  • Oral rehydration fluids by gavage, three times daily, 20 mL/kg normal body weight (P14.5.w6). N.B. not if head carriage cannot be maintained. (B23.38.w2)
  • Parenteral fluids as required (e.g. bolus injection, 15-35 mL/kg into the medial tarsal or cutaneous ulnar vein, three times daily). (B23.38.w2)
  • Provide water for drinking at all times.
  • Feeding: offer appropriate food for the species concerned. Force-feeding may be necessary initially, or gavage feeding (stomach tubing) two or three times daily - maximum 5% body weight per feed.
  • Initial gavage diet: balanced isotonic liquid diet high in calories and with simple dietary components to maximize nutrient absorption. Warm to near body temperature. High vitamin A and vitamin K levels are suggested. Cultured yogurt or lactobacillus preparations may be useful to enhance digestion and nutrient absorption. (B23.38.w2)
  • For further information see: Oiled Wildlife Admission and Stabilisation

Oil removal - washing: see Cleaning Oiled Wildlife

Post-washing:

  • Once dry, birds should be given access to a pool with a constant water flow and surface skimming drainage (surface overflow) to remove any remaining oil or detergent.
  • Pool edges should have shallow slopes (multiple shallow ramps may be used as an alternative) and pools should be easy to clean. "Astroturf" matting is suitable for covering pool edges.
  • Suitable food should be provided. Fish for birds on pools should be provided in shallow trays away from the water to reduce the risk of contamination of the water with fish oils; non-oily fish are preferred for the same reason.
  • Inappetant birds should be fed by stomach tube if necessary; oral fluids should not be necessary once birds are on water.
  • Birds should be monitored for general behaviour and continued waterproof status. Excessive preening may indicate a continuing feather problem.
  • Misting birds with water (e.g. using a spray bottle or a fine mist attachment for a garden hose) will stimulate preening and is also useful for evaluating waterproofing (B23.38.w2).
  • For further information see: Preparation for Release (Post-washing Care)

Release: Birds should not be released until:

  • Plumage is waterproof (check particularly around vent and in the axillae - point of holding during rinsing); check plumage of diving ducks after diving.
  • PCV is within the normal range (usually 37-53%), or at least within 10% of normal for the species.
  • Body weight is normal
  • Normal behaviour - feeding, preening, swimming, diving - has been noted.

N.B. :-

  • Good ventilation is essential at all stages to reduce the risk of Aspergillosis, and also to remove fumes given off by recently-oiled birds.
  • Disturbance, including loud noises, music, humans walking past etc. should be minimized to reduce stress
  • Waterfowl will usually be hospitalized for at least four to five days, possibly ten days or more for seaducks.
  • Consideration of natural social groupings is important; colonial species preferably should be maintained in groups and if this is not possible then in at least visual contact with conspecifics.
  • Avoid overcrowding.

(B11.36.w3, B18, B23.38.w2, D6, P14.5.w5, P14.5.w8)

MAMMALS Respiratory distress:
  • For individuals showing severe respiratory distress (tachypnoea, dyspnoea, cyanosis (blue/black mucous membranes): (D208.5.w5)
    • Check the airway;
    • Provide oxygen;
    • Appropriate drugs for stimulation of breathing or dilatation of airways. 

    (D208.5.w5)

  • For interstitial emphysema:
    • Supportive care. Mild sedation may be beneficial to calm excited/agitated individuals showing hyperventilation or laboured breathing. (D208.5.w5)

Vomiting:

  • Control the underlying causes of the vomiting. (D208.5.w5)
  • Correct any fluid deficits and electrolyte imbalances; (D208.5.w5)
  • Maintain adequate nutrition; (D208.5.w5)
  • Carefully consider the volume and frequency if food is being given by stomach tube, and the details of how the tubing is being carried out. (D208.5.w5)
  • If possible, stop feeding for one or two feeds (maintaining hydration by parenteral fluid therapy) then restart with electrolyte solution and gradually return to full-strength food formula. (D208.5.w5)

See also: Oiled Wildlife Admission and Stabilisation

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Preventative Measures

Vaccination WATERFOWL --
Prophylactic Treatment

WATERFOWL

--
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Environmental and Population Control Measures

General Environment Changes, Cleaning and Disinfection

WATERFOWL

  • Oil spills should be reported to the appropriate authorities: in the UK to the Environment Agency (0800 807060), in the USA to the National Response Center (1-800- 424-8802).
  • Oil should be removed from the environment if at all possible and as rapidly as possible.
  • See: Preventing Oiling of Wildlife; Oil Spill Public Education
Population Control Measures WATERFOWL

HAZING, BAITING and PRECAUTIONARY CAPTURE CAN SUBSTANTIALLY DECREASE THE NUMBER OF BIRDS AFFECTED AND THEIR USE SHOULD BE GIVEN HIGH PRIORITY; however, expert advice should be obtained regarding the suitability of use of each measure.

  • Birds may be discouraged from using an area known to be polluted with oil, if possible, for example by the use of scaring (Hazing) devices. Careful consideration needs to be given to the use of such techniques and assessment that they have the anticipated effect on a population.
  • Birds may also be attracted to locations not affected by a known contamination event (Baiting).
  • Sedentary or flightless (e.g. during moult) populations may need to be taken into temporary accommodation until clean-up operations have been completed or possibly relocated.

(B36.42.w42)

Isolation, Quarantine and Screening WATERFOWL
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