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Environmental Assessment

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Introduction and General Information

  • A wide variety of environmental factors may affect the occurrence of disease, by their effect on the species directly, on other disease agents, and on the interaction between the species and the disease-producing agents. Assessment of the environment should be an integral part of disease investigation alongside the history (History & Documentation), clinical examination (Physical Examination of Mammals) and if applicable post mortem examination (Necropsy of Mammals).
  • Both general and specific features of the environment should be noted, considering whether the environment appears to meet the needs of the animal(s) for shelter, food, water and fulfilment of behavioural requirements such as nest sites/materials, or whether the presence or lack of certain elements may be acting as stressors, as well as specific details which may be associated with particular disease conditions.

General:

  • Habitat type: e.g. coastal, mountain, freshwater, grassland, cropland, urban, moorland, coniferous forest, tropical forest.
  • For captive animals: enclosure size, general type (e.g. paddock, aviary, enclosed building, pet cage).

Specifics: details of the direct physical environment in which the animal lives or lived, including:

  • Water
  • Substrate
  • Vegetation
  • Fauna
  • Atmospheric conditions

IT IS IMPORTANT TO REMEMBER THAT:

  • A full appreciation of the data gained from environment assessment requires an understanding of how environmental factors may affect the animal(s), any disease-producing organisms/disease factors, and the contact between them.
  • The animal species present in the area, including e.g. predators/scavengers, and possible disease vectors, should be considered as a part of the environment for assessment purposes.
  • Local environment and microclimate conditions may be different from the general conditions in an area.
  • If an animal is presented away from its usual environment then information about its normal surroundings, or the area in which it was found, should be described as part of the history (see: History & Documentation).
  • If samples are to be taken for further analysis, the laboratory which is to do the analysis should be contacted in advance regarding the amount to be collected, details of sampling methods, preferred container type, conditions required during shipment, any time constraints. Whenever possible, several samples should be taken initially: usually it is easier to discard unwanted samples than to go back and collect more.

(B36.1.w1, B127)

Waterfowl Consideration

  • Waterfowl spend a great deal of their time on water or on land. Therefore consideration of the water conditions and substrate are a very important part of environmental assessment.
  • Many wild waterfowl species are migratory, and mix together in high concentrations e.g. at staging posts. Thought should be given to the origins of the different species.
  • Waterfowl may feed in one area and rest or roost in another. It is important to remember that a toxin or infectious agent may be picked up in one area, but that the waterfowl involved may have moved to another area (either on migration or as part of a daily routine) before the effect is seen.

(B36, B127, V.w5)

Crane Consideration

Elephant Consideration

  • Elephants are social animals that need contact with other elephants, therefore sufficient space should be provided for a group of elephants to allow them to interact adequately. (B336.53.w53)
  • The facilities should provide protection from the weather; simple protection from the elements may be sufficient in warmer climates but in colder regions provision of heating and protection from draughts will be important. (B336.53.w53)
  • The facilities should secure the elephants safely; sturdy housing is required, particularly for adult bulls. (B336.53.w53)
  • Indoor as well as outdoor housing facilities are required. (B336.53.w53)
  • The facilities should provide the opportunity for adequate exercise. (B336.53.w53)
Bear Consideration
  • Bears are solitary in the wild but commonly are maintained in pairs or larger groups in captivity.
  • Facilities for bears should enable activities such as climbing, digging and bathing, and should allow bears privacy from one another.
  • Bears are very strong and may tear logs, other furnishings and toys apart.
  • For further information see: Accommodation Design for Mammals, Mammal Behavioural Requirements
Lagomorph Consideration
Domestic rabbit
  • When a domestic rabbit is brought to a veterinary surgery, information about its home environment generally must be gained from a good history. (V.w5) See: History & Documentation
    • The information following is relevant whether the environment is visited or has been described.
Wild lagomorphs
  • For captive lagomorphs, information should be available on the size and type of enclosure, as well as whether it was housed with other conspecifics or in a mixed-species enclosure.
  • For free-living lagomorphs, information should be obtained regarding where it was found - both the exact location and the type of area (e.g. in a paddock or a cultivated field, by a road, in a garden).
Ferret Consideration

 

  • When a domestic ferret is brought to a veterinary surgery, information about its home environment generally must be gained from a good history. (V.w5) See: History & Documentation
    • The information following is relevant whether the environment is visited or has been described.
Bonobo Consideration
  • Bonobos are highly intelligent, and the environment provided for bonobos (and for other great apes) should be complex and changeable, providing stimulation so that the bonobos can express curiosity, exploration and intelligence, enable foraging, encourage arboreal locomotion, and providing social contact between bonobos. (B336.39.w39, D386.App1.w6)
  • Bonobos are highly social, but also need to be able to retreat from their conspecifics; the facilities should enable both social interaction and retreat.

Published Guidelines linked in Wildpro

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Water Conditions

Water is essential to all living organisms. Whether present as a lake or provided in a drinking bottle, the condition of available water should be noted. Factors which may be relevant in the investigation of a disease include:
  • General size and type - 20 hectare natural lake, large river, clay-lined reservoir, 10 foot diameter membrane-lined pond, non-tip bowl, drinking bottle etc.
  • Source - e.g. spring-fed, mains water, river-abstracted, natural run-off, road run-off, sewage effluent.
  • Vegetation - presence of emergent, submerged or floating vegetation; algal blooms.
  • Visible contaminants - e.g. oil, foam.
  • Banks - e.g. steep or shallow, stable or eroded, bare or vegetated, natural or concrete
  • Water temperature - N.B. this may vary within a body of water, e.g. related to sources.
  • Water quality - Oxygen saturation, pH, salinity, nutrient loading (eutrophication).
  • Signs of recent change in water level - non-aquatic vegetation under water, indicating increase in water level; aquatic vegetation out of water indicating drop in water level; line of debris above present water level indicating recent flood and subsequent drop in level; area of wet/dried mud around small remaining water area, suggesting drought or seasonal water body.
  • Any smell?

Samples which may be taken for further analysis include: Water, bottom mud, algae if present, surface water with visible contaminant, if present.

(B15, B36, B127)

Waterfowl Consideration Water conditions are vitally important for the health of waterfowl. Among the water conditions which may be linked directly or indirectly with disease are:
  • Steep banks - may cause difficulty for animals exiting water, (see: Drowning).
  • Shallow banks - large surface area including vegetation and associated invertebrates may be flooded or exposed with small variations in water level. Large area of shallow, potentially sun-warmed, water.
  • Visible algal bloom - may contain toxins (see: Blue-Green Algae Toxicity)
  • Water moving from one area/enclosure to another (e.g. serial filling of ponds) allows transport of micro-organisms/ toxins to downstream locations e.g. Avian Cholera, Duck Plague.
  • Still, shallow water - promotes growth of Daphnia populations (see Echinuriasis (Acuariasis)).
  • Saline water: in the absence of fresh water for drinking, may lead to salt toxicity. In association with a sudden temperature drop, may lead to Salt Encrustation.
  • Presence of ice - (see: Drowning, Ice Entrapment, Frostbite).
  • Presence of surface contaminants (see- Oiling, Wet-Feather, Chilling/hypothermia).
  • Heavy surf conditions: (see - Drowning, Impact Injury)
  • pH - affects survival of micro-organisms (see: Avian Cholera, Duck Plague)
  • Presence of decaying organic matter, including carcasses (see: Avian Botulism).
  • High nutrient load (eutrophication) (see: Blue-Green Algae Toxicity).
  • Little or no large-leaf (macrophyte) vegetation (submerged, floating or emergent) - may predispose to algal blooms (see: Blue-Green Algae Toxicity).
  • Drought or Freezing causing overcrowding on remaining water areas.
  • Water temperature: optimal bacterial growth of Clostridium botulinum occurs at 25-40 C (particularly 30-37 C); N.B. warmer than expected water temperatures may occur (e.g. in winter) due to outputs of water from power stations (P17.50.w1, B15) (See: Avian Botulism). Increased temperature (e.g. 18-20 C versus 4 C) may increase survival of Pasteurella multocida in water (see: Avian Cholera). Cold temperatures may favour the survival of Herpesviridae: Duck Enteritis Virus (see: Duck Plague).
  • Microenvironmental conditions: Likelihood of a botulism outbreak is significantly influenced by pH, salinity, temperature, and oxidation-reduction potential in the sediments and water column (B36.38.w38). Temperature in carcasses in winter may be considerably higher than that of the surrounding environment, allowing development of both bacteria and maggots (B15) (see: Avian Botulism). Salinity, presence of organic matter (e.g. carcasses), presence of other micro-organisms and increased temperature (e.g. 18-20 C versus 4 C) may all increase survival of Pasteurella multocida in water (see: Avian Cholera).

(B15, B36)

Crane Consideration
  • Fresh, clean water should always be available for cranes to drink.
  • Most of the cranes are wetland species and appreciate access to water bodies. However, there is also a risk of water as a source of infectious organisms.
    • Lack of access to pools and associated soft mud substrate is thought to be a factor in the development of Hock Osteoarthritis in Siberian Cranes
    • There have been outbreaks of Avian Botulism in the wild with cranes affected, and at least one outbreak of botulism in a North American zoo in which cranes were affected. (B115.8.w4)
  • If a large water body (e.g. a reservoir) is drained for maintenance, there is a risk of remaining silt acting to trap free-living cranes landing on it. See: Foreign Body Entanglement & Snaring; Capture Myopathy.
  • Drowning is most likely to be a problem if chicks are unable to exit a water body.

Elephant Consideration

  • Access to fresh and potable water daily is essential. (B336.53.w53)
  • Some infectious diseases have been reported to be transmitted through contaminated water, for example Anthrax and Salmonellosis.
Bear Consideration
Lagomorph Consideration
Domestic rabbit
  • Access to drinking water is essential unless the rabbit is on a diet very high in moisture. 
  • Note whether drinking water is provided in a bowl, a sipper bottle, or both. (B601.2.w2)
    • Dehydration may occur if a rabbit is provided with a bottle only and has not learned to drink from it. (B600.3.w3)
    • For rabbits with a large dewlap, drinking from a bowl may result in repeated wetting of the dewlap and subsequent development of moist dermatitis. (B600.3.w3)
Wild lagomorphs
  • For wild lagomorphs in permanent human care, the same considerations apply as for domestic rabbits.
Ferret Consideration
  • Access to drinking water is essential at all times. (B602.1.w1, B339.9.w9, B631.17.w17, B652.5.w5, J213.2.w5)
  • Check that drinking water is not provided in a galvanised water container, due to the risk of Zinc Toxicity. (B232.3.w3)
Bonobo Consideration
  • While wild bonobos have been seen to drink only rarely (probably getting most of their fluid requirement from food, drinking water should be available at all times in both indoor and outdoor enclosures. (D386.5.1.w5a, D386.App1.w6)
  • More than one source of water should be provided, so that the water cannot be monopolised by dominant individuals.  (D386.5.1.w5a)

Associated techniques linked from Wildpro

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Substrate and ground-covering vegetation condition

  • The general type and condition of the substrate and ground-covering vegetation such as grass should be noted:
  • Soil type: e.g. sandy and well drained; thick clay and poor drainage (promotes survival of parasites); a thin layer over rock; or frank mud?
  • Artificial substrate: e.g. gravel, sand, bank and chippings, concrete or wire floored?
  • Ground covering vegetation: even sward of grass, rank and overgrown, short and overgrazed?
  • Snow or ice covering ground?
  • Quantities and appearance of droppings/faeces and urine: e.g. pools of urine, large amounts of faeces/droppings visible, blood-staining, frank diarrhoea?
  • Presence of visible contaminants? This includes e.g. mouldy food items.
  • Presence of salt or other potential attractants on roads?
  • Charring of the ground, indicative of fire or lightning strike?
  • For animals in collections, or in temporary/hospital accommodation, it is important to consider whether the substrate is appropriate for the species. Inappropriate substrate may lead to physical trauma and act as a stressor. Substrates such as sand and gravel may be ingested and, in excess, be associated with impactions. This may also occur with e.g. bark or wood chippings in some species such as some psittacines (Psittaciformes - Parrots (Order)).
  • Erosion, excessive puddling, excessive faeces and poor grass cover on a grazing area may all indicate overcrowding. Large quantities of faeces/urine left in an enclosure may be indicative of general poor management. Too short grass may lead to malnutrition of grazing species if alternative green food is not provided, as well as promoting increased transfer of infective stages of parasites.
  • Samples: soil, mud, faeces/droppings, grass or other ground-cover vegetation may be sampled and tested for the presence of pathogenic micro-organisms and infective stages of macroparasites. Samples of possible materials should be collected.

(B36, B127, B134.w1)

Waterfowl Consideration
  • The presence of large quantities of concrete, particularly rough concrete, may cause abrasion of feet (see: Bumblefoot).
  • Thick snow, or ice, may prevent access to food sources, resulting in Starvation, or may force waterfowl to use sub-standard food sources, such as mouldy silage or grain (see: Aspergillosis).
  • Ice or snow covered ground, particularly in the absence of open water, and without an area of e.g. straw provided, may be associated with Frostbite.
  • Wet conditions - associated with increased Gapeworm Infection.
  • Presence of contaminants: Oil - (see: Oiling), lead shot - (see: Lead Poisoning), mouldy food (see: Aflatoxicosis (Mycotoxicosis)).
  • Slippery surfaces in brooder boxes may be associated with Splay Leg.
Crane Consideration

Elephant Consideration

Bear Consideration --
Lagomorph Consideration
Domestic rabbit
  • Rabbits kept in the house and given unsupervised access to carpets may eat the carpet.
  • If the rabbit is litter-box trained, what type of litter is used in the box? (B601.2.w2)
    • Clay-based litters if eaten can cause impaction of the caecum. (B600.3.w3)
    • Pine shavings may be hepatotoxic. (B600.3.w3)
Wild lagomorphs
  • As for other grazing species, check whether the grass sward is adequate or if it is poor, which may indicate overcrowding, and may lead to poor nutrition and increased transfer of parasites.
Ferret Consideration Lack of access to areas for digging may lead to overgrown nails.
Bonobo Consideration Consider both the substrate in the outdoor area and in the indoor area.
  • Outdoor substrates may affect exposure to e.g. pollens which can act as allergens (Atopy in a Bonobo) while indoor substrates may affect skin condition and general susceptibility to skin problems, and dust levels, which can have respiratory effects such as possibly increasing the likelihood of respiratory tract infections such as air sacculitis (Laryngeal Air Sacculitis in Bonobos). (P133.2012.w3)
    • At Twycross Zoo, straw as bedding was associated with dry skin and development of skin rashes; this did not occur when woodwool was used as bedding. (R1.19Jan2009.w1)
  • Absence of complex substrates also may be a factor leading to behavioural problems. See: Mammal Behavioural Requirements - Stress, Behavioural Problems and Stereotypies
Associated techniques linked from Wildpro

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Vegetation

  • Vegetation is important as a source of shelter, food and nesting sites.  Factors to consider include:
  • Signs of excessive browsing of trees/bushes which may indicate overcrowding/food shortage.
  • Presence of plants which may be poisonous; signs that these may have been consumed.
    • Note not only plants inside an enclosure, but also any which are nearby and possibly within reach of the animal(s), or of visitors who could have offered them to the animal (s), and any parts of plants remaining on the ground) indicating they have been recently given to the animal(s).
    • Consumption of poisonous plants is more likely to occur when normal vegetation is scarce.
  • Excessive vegetation providing cover for pest species of both vertebrates and invertebrates, and preventing sunlight reaching potential pathogens.
  • Insufficient vegetation leading to increased susceptibility of nesting birds to predation, decreased ability of animals to avoid each other in the event of intra- or interspecific conflict.
  • Samples of potentially toxic plants should be taken for definitive identification and if necessary confirmation of toxicity.

(B35.2.w6, B36, B127, P6.4.w1)

Waterfowl Consideration
  • Sooty mould which grows on Osier willows is one cause of wet-feather - (see: Wet-Feather)
  • Excessive vegetation cover in enclosures providing dark damp habitats suitable for bacterial growth (see: Avian Tuberculosis).
  • Vegetation cover particularly on waterside banks which may hide sick and dead waterfowl (see: Avian Botulism).
  • Charring of vegetation may indicate fire or lightning strike (see: Electrocution, Burns.)
  • Insufficient vegetation cover may prevent individuals escaping from aggressive interactions.

(V.w5)

Crane Consideration

Elephant Consideration

Bear ConsiderationClick here for full page view with caption Check which plant species are present in or near the enclosure (which may be in reach of the bears or have been offered to the bears); the presence of potentially toxic species may lead to poisoning. See:
Lagomorph Consideration
Domestic rabbit
  • A wide variety of plants might be toxic to rabbits (Plant Toxicities in Rabbits). This should be considered for house rabbits with possible access to indoor plants, as well as for rabbits given free run of the garden. (B600.2.w2, B601.1.w1)
    • Dieffenbacchia (dumb cane) is an example of a poisonous house plant. (B601.1.w1)
Wild lagomorphs
  • If lagomorphs are maintained in an outdoor enclosure where it is intended that growing vegetation should provide significant nutrition, check that sufficient edible vegetation is available.
  • It is unlikely that a wild lagomorph in its native environment would eat toxic plants. However, this possibility does exist for lagomorphs in human care, if toxic plant species have been provided in their enclosure.
  • Check whether appropriate vegetation is available for the lagomorphs to hide in.
Ferret Consideration --
Bonobo Consideration
  • Check which plant species are present in or near the enclosure which the bonobos may be able to access and eat, or which may have been offered to the bonobos, as the presence of potentially toxic species may lead to poisoning. (D425.1.2.w1b)
    • It is particularly important to check plants in new enclosures. (D425.1.2.w1b)
  • Consider exposure to pollens which might act as allergens (Atopy in a Bonobo). (P5.37.w2)
Associated techniques linked from Wildpro

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Man-Made Structures

  • Increasingly, man-made structures from roads and fences to buildings and power lines are becoming a part of a wide variety of habitats. One of the most obvious considerations is the possibility of wild animals colliding with such structures. Moving vehicles, including cars, boats and aircraft, provide an additional hazard in this respect.
  • For captive animals, the materials and construction of enclosures, whether a small cage, an aviary or a large paddock must be assessed as a part of their environment. Factors to consider include:
  • Has wood been treated with preservative or paint? If so, when, and with what?
  • What sort of roofing has been used in aviaries? Is there e.g. chicken wire on which an animal might injure itself on collision (e.g. scalping injuries in pheasants)?
  • Are there posts on the inside of enclosures where animals might collide with them when panicked?
  • If shelters are being provided for protection from inclement weather, is there any evidence (e.g. presence of droppings) to suggest they are being used?
  • Is the construction of an external boundary fence or an aviary sufficient to keep out the local predators?
  • Are perches, sleeping platforms etc. suitable in size, structure and quantity for the species concerned?
  • Are doors between e.g. outside and inside accommodation of an appropriate size such that the animals will pass through them freely?

(V.w5, V.w6)

Waterfowl Consideration
  • Fences, buildings, windows, telephone wires and bridges all have an associated risk of collisions (see: Impact Injury, Lacerations / Punctures).
  • Gates of canal locks, boats and e.g. doors and gates may lead to crushing injuries (see: Crushing) (B9.6.w1).
  • Wet roads may also lead to collisions, as waterfowl sometimes land on them, apparently mistaking them for water (see: Impact Injury).
  • Power lines hold a risk of both collision and electrocution (see: Impact Injury, Electrocution).
  • N.B. power lines and telephone lines over botulism-prone marshes or water-bodies carry an additional risk, as carcasses of birds colliding with these wires may act as a focus for the development of a botulism outbreak (see: Avian Botulism).
  • Lack of perches, or provision of metal perches, increases the susceptibility of species such as Whistling-ducks to frostbite (see: Frostbite).

(V.w5)

Crane Consideration

Elephant Consideration

  • Housing and fencing should be sufficiently sturdy, particularly if adult bulls are being contained. (B336.53.w53)
Bear Consideration
Lagomorph Consideration
Domestic rabbit
  • Consider whether any wooden structures that the rabbit may have gnawed have been treated with toxic compounds.
  • Check the gauge and opening diameter of wire netting, including floor netting: 
    • Is the floor netting inappropriate and leading to excess pressure on the skin? 
    • Is there any chance the rabbit could catch a limb through the netting?
  • Is a carry cage with a front-opening door used? If so, is there a risk of the rabbit getting a leg caught between the door and the frame?
Wild lagomorphs
  • For wild lagomorphs in permanent human care, the same considerations apply as for domestic rabbits.
  • For free-living lagomorphs, collisions with artificial structures such as fences, and particularly the possibility of collision with moving vehicles should be considered.
Ferret Consideration Assess the ferret's housing. Housing should be well-built without any gaps allowing a ferret to escape; ferrets can fit through very small gaps. Protruding nails could result in lacerations or punctures, as could broken glass or discarded tins in areas to which the ferret has access. (B651.9.w9, J16.30.w1)

Check whether ferrets have any access to electrical cables, particularly in the house if ferrets are allowed access.

Bonobo consideration
  • Check that no structures or items offered are covered with lead-containing paint, as this might be ingested, leading to Lead Poisoning. (B644.5.w5)
  • Check that shelter and shade are freely available. (V.w5)
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Atmospheric conditions

  • General climate.
  • Air temperature - regarding hypothermia and hyperthermia, also both extremes of temperature and sudden changes in temperature as a stressor. 
  • Precipitation.
  • Sunny weather? - possibility of e.g. heatstroke/hyperthermia (Sunstroke / Heatstroke), sunburn (Burns and Smoke Inhalation).
  • Overcast? - increased survival of bacteria etc. in the environment.
  • Humidity - affects pathogen survival.
  • Dusty conditions - affects respiratory system and may predispose to respiratory infections.
  • Wind strength and direction: may affect distribution of e.g. contaminants/toxins in a water body.
  • Ventilation in enclosed spaces - adequate or inadequate?

(B15, B32.1.w34, B36, B127)

Waterfowl Consideration
  • Air temperature: (see: Chilling/Hypothermia, Sunstroke / Heatstroke). Also consider role of extremes of temperature and sudden changes in temperature as a stressor. 
  • Inclement weather - associated with outbreaks of avian cholera (see: Avian Cholera)
  • Dusty conditions - has been linked to an outbreak of Aspergillosis.
  • High humidity and inadequate ventilation - linked to e.g. brooder pneumonia (see: Aspergillosis), bacterial infections.
  • Algal blooms and surface contaminants may be concentrated on the downwind side of a water body.

(B11.40.w8, B15, B36, B127)

Crane Consideration

Elephant Consideration

  • In warm climates, shelter should be provided to avoid conditions such as Sunstroke - Heatstroke.
  • In cold climates, a indoor building providing a temperature of at least 15 C is strongly recommended to avoid conditions such as Frostbite.
  • Sick and debilitated animals should be kept in an indoor area maintained at 21 C.
  • Consider whether there have been high levels of sunshine, or conversely high precipitation and/or wind-chill. (B336.53.w53)
    • Elephants have a low surface area-to-volume ratio, lose heat slowly and can become used to temperatures dropping down to freezing, tolerating such temperatures without apparent discomfort, but this depends on other factors such as wind-chill and precipitation. (B336.53.w53)
    • Elephants are susceptible to sunburn. See: Burns and Smoke Inhalation 

(B336.53.w53)

Bear Consideration Check the provision of adequate shade from sun, provision of cool areas in hot conditions, and shelter from cold, wind and rain.
Lagomorph Consideration

Lagomorphs are generally resistant to cold but more susceptible to overheating.

Domestic rabbit
  • Check the provision of adequate shade from sun, provision of cool areas in hot conditions, and shelter from cold, wind and rain. (B600.2.w2, B606.1.w1)
    • It is essential that rabbits have adequate shade and can get away from hot sunshine. (B600.2.w2)
  • The ideal temperature range for rabbits is 15 - 20 C; the temperature should be maintained under 28 C (82.4 F). (B602.13.w13). A minimum-maximum thermometer should be used to confirm the temperatures where the rabbit is kept. (B600.2.w2)
    • Rabbits may choose to remain outdoors in cold weather, but should always have a dry enclosed shelter, with plenty of bedding, to retreat into. (B600.2.w2)
  • Good ventilation, draft-free, should be provided; this is important since poor ventilation promotes respiratory disease. (B601.1.w1,B604.2.w2)
    • If the rabbit is kept in a hutch, check that ventilation is adequate. This is of particular concern if the hutch is kept in a shed or garage rather than outside. (B600.2.w2)
Wild lagomorphs
  • As with domestic rabbits, check whether other lagomorphs in a zoo or other permanent human care situation have adequate shade and shelter.
  • Ochotona spp. - Pikas in particular are very susceptible to overheating in hot temperatures.
Ferret Consideration
Bonobo Consideration
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Fauna

In investigating a disease incident, the species present in the local environment must be considered:
  • Carcasses visible: species, numbers, stages of decomposition.
  • Live animals visible - species, numbers, ratio relative to carcasses (i.e. is there a mis-match between species present and species affected?).
  • Scavengers/predators present in the area - indicates expected removal of dead/sick animals.
  • Opportunity for intraspecific and/or interspecific conflict. Particularly in captive situations, where animals are unable to flee an aggressive encounter. N.B. animals protecting territory, mates, nests or offspring may be more aggressive than usual.
  • Carrier animals - possibility of microparasites or macroparasites carried by one species having a greater pathogenic effect on another species. e.g. toxoplasmosis is more likely to be seen in an area with a large population of cats (Th3).
  • Overcrowding - as a general stressor, also increases rate of transmission of infectious disease, including increasing contamination of the environment with both microparasites and infectious stages of macroparasites. Some diseases are specifically linked to seasonal aggregations of animals.
  • Presence of vectors/intermediate hosts.
  • For animals in collections, possible contact with wild or feral animals

(B11.2.w16, B15, B36.1.w1, B127)

Waterfowl Consideration
  • Seasonal aggregations of waterfowl, e.g. at migratory staging areas, on wintering grounds, at breeding or moulting areas (see: Avian Cholera).
  • High population density in the breeding season may be associated with excessive pursuit of female ducks (see: Drowning, Scalping).
  • High population density may promote infectious diseases such as Avian Cholera, Duck Plague.
  • Presence of wild mallard drakes in UK collections in spring (see: Duck Plague).
  • Presence of Simulium spp. for transmission of Leucocytozoon (see: Leucocytozoonosis).
  • Presence of nasal leeches: (see: Leech Infection).
  • Possibility of conflict between individuals of the same or similar species, particularly during the breeding season (see: Lacerations / Punctures).
  • Possibility of injury from other species, both predators and incidental/accidental (see: Lacerations / Punctures, and Crushing).

(V.w5)

Crane Consideration

Elephant Consideration

--
Bear Consideration
  • Injuries from conspecifics are not uncommon. (B10.48.w43, B16.9.w9, B64.26.w5, D247.7.w7, P85.1.w2)
  • The social situation in which bears are kept may affect disease; it has been suggested that the development of clinical skin disease in Ursus maritimus - Polar bear may be associated with social stress, being more likely to develop in bears kept in groups and specifically in individuals in the group which are of low social rank. (P6.1.w5)
Lagomorph Consideration
Domestic rabbit
  • Rabbits kept together may fight and injure one another (Lacerations & Punctures, including bite wounds).
    • This is more likely when rabbits are first introduced, and if rabbits are non-neutered adults.
    • Males are more likely to fight than are females. 
    • A dominant entire (not spayed female) may injure the skin of other females by mounting them excessively when reproductively receptive.
  • Rabbits may be injured by other pets in the household, such as cats or dogs. (J213.2.w2)
  • If housed outside or given unsupervised access to an outdoor area which is not predator-proof, they may be attacked by cats, dogs, and local wildlife - foxes, stoats, weasels etc. (B604.2.w2, B606.6.w6)
Wild lagomorphs
  • In general, the same considerations apply as for domestic rabbits. Check whether the lagomorph was being maintained alone, in a pair, group with other conspecifics or in a mixed-species exhibit. 

(V.w5)

Ferret Consideration
Bonobo Consideration
Associated techniques linked from Wildpro

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Food & Feeding Considerations

Food is one of the essential requirements for survival (J56.19.w1). Insufficient food available may lead to malnutrition and starvation. Inappropriate food may give rise to nutritional imbalance. Food may also be contaminated and contain e.g. toxins or pathogenic micro-organisms. Factors to consider include:
  • Food availability: quantity, type. Monotonous or varied.
  • Food freshness & quality - presence of mould, whether meat and fish are left lying around for prolonged periods.
  • Feeding method (for captive animals): e.g. in containers or scatter-feeding. Food scattered around an enclosure may be more likely to become contaminated. Food provided in a container may be monopolised by some individuals, with others not getting their fair share; this is particularly true for favoured items and may lead to inappropriate nutrition in high-ranking/dominant individuals gorging on preferred items as well as in low-ranking/subordinate or shy individuals not receiving some items.
  • Comparison of food offered with food eaten. Provision of a balanced diet does not necessarily mean consumption of a balanced diet.
  • For wild carnivores, assessment of food availability involves consideration of available prey species.
Consideration of foods known to have been ingested, e.g. by observation or from post mortem examination (necropsy) findings, should be used alongside environmental assessment (see: Necropsy of Mammals, History & Documentation).

(B11.2.w16, B15, V.w5 J56.19.w1)

Waterfowl Consideration

(V.w5)

Crane Consideration

Elephant Consideration

Bear Consideration

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Lagomorph Consideration
Domestic rabbit

Domestic rabbits are reliant on their owners to provide food. It is important to assess:

  • Does the rabbit have access to an area to graze grass and other natural vegetation every day, most days, only in summer, rarely or never?
    • Natural grass provides appropriate nutrition for rabbits, including essential fibre and calcium.
    • There is a potential risk of the rabbit eating toxic plants in a garden, but in practice this appears to be rare.
    • If carnivores have access to the grazing area (when the rabbit is not present!) there is an increased risk the rabbit may encounter parasites such as tapeworm cysts. 
  • Is the rabbit provided with hay? If so, how is this fed - on the ground, in a solid hopper or in an overhead hay rack.
    • Hay on the ground is more likely to become soiled.
    • If hay is provided in a rack, there is more chance of dust and seeds getting into the rabbit's eyes.
  • Are green foods, other vegetables and fruits given to the rabbits. If so, what is provided, how often and how much?
  • If grass is picked for the rabbit, where does this come from? Is it an area which wild rabbits or other animals could have access to?
    • If grass is picked in an area which wild lagomorphs have access to, there may be a risk of various disease organisms being transmitted from the wild rabbit.
    • If carnivores have access to the area the grass is taken from there is an increased risk the rabbit may encounter parasites such as tapeworm cysts (Tapeworm Cyst Infection in Lagomorphs) and in North America, eggs of Baylisascaris spp. (Cerebrospinal Nematodiasis in Lagomorphs). 
  • Is the rabbit given a concentrate food? If so is this a complete pelleted diet? A rabbit mix? 
    • How much is the rabbit given?
    • If given a mix, does the rabbit eat all parts of the mix, or leave some types of food and eat other items first? If so, is the food replaced/replenished, or left until all the parts of the mix have been eaten?
      • Preferably get the owner to bring in the food bowl showing what is left behind after the rabbit has eaten.
  • Nutrition-related diseases which might be seen include:
Wild lagomorphs
  • In general, free-living wild lagomorphs should have access to a balanced diet.
  • In winter, food may be made unavailable by e.g. deep, frozen snow.
  • Drought may decrease food availability.
  • Note: For wild lagomorphs in captivity, the same considerations apply as for domestic rabbits.

(V.w5)

Ferret Consideration
  • Ferrets have a short digestive tract and rapid passage of food through their gut; they are designed to eat little and often. Food and water should always be available. (B339.9.w9, J213.2.w5)
    • Hypoglycaemia is a particular risk to ferrets with Insulinoma if food is withheld. (B232.9.w9)
  • Check on the diet given. (J16.30.w1)
  • If a recently-acquired ferret is not eating, check whether its background is known and what foods it was given previously. A ferret which has previously had a natural -type diet (e.g. parts of rabbit carcasses, whole rodents) may not recognise or accept a complete pelleted diet. (V.w44)
  • Nutritional diseases are rare in ferrets. However, check that the diet is adequate.
  • Nutritional diseases which should be considered include:
Bonobo Consideration
Associated techniques linked from Wildpro

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Human Health Considerations

  • Care must be taken when taking samples of materials which may be toxic for humans, such as oil and pesticides (B36).
  • Consider the possibilities of exposure to zoonotic agents in animal secretions and excreta, and in the environment. (V.w5)
Waterfowl Consideration
  • Most causes of disease in waterfowl are not due to zoonotic agents. However, the possibility of zoonoses (e.g. Salmonellosis) should always be considered. (V.w5)
Crane Consideration
  • Most causes of disease in cranes are not due to zoonotic agents. However, the possibility of zoonoses (e.g. Salmonellosis) should always be considered. (V.w5)

Elephant Consideration

Bear Consideration
Lagomorph Consideration Consider the possibilities of exposure to zoonotic agents in animal secretions and excreta, and in the environment. (V.w5)
Domestic rabbit
  • There have been isolated reports of human salmonella infections (see: Salmonellosis) after contact with infected domestic rabbits. (B600.3.w3)
Wild lagomorphs
  • Free-living lagomorphs are closely associated with Tularemia in some areas (not UK). (B209.18.w18)
Ferret Consideration Consider the possibilities of exposure to zoonotic agents in animal secretions and excreta, and in the environment. (V.w5)
Bonobo Consideration Consider the possibilities of exposure to zoonotic agents in animal secretions and excreta, and in the environment. (V.w5)
Associated techniques linked from Wildpro
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Authors & Referees

Authors Debra Bourne MA VetMB PhD MRCVS (V.w5) & Gracia Vila-Garcia DVM, MSc, MRCVS (V.w67)
Referees Suzanne I. Boardman BVMS MRCVS (V.w6); Frances Harcourt-Brown BVSc FRCVS (V.w140); Susan K. Mikota DVM (V.w72)

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