Salt Poisoning in Waterfowl and Elephants

Disease Summary

Alternative Names (Synonyms)

• Salt Toxicity
• Water Deprivation

(For waterfowl, see also Salt Encrustation)

Disease Type

Infectious/Non-Infectious Agent associated with the Disease

Infective "Taxa"

Non-infective agents

• Salt

Physical agents

References

Disease Author

Major References / Reviews

Code and Title List

Elephants:

B385.4.w4
J151.16.w1

Other References

Code and Title List

Detailed Clinical and Pathological Characteristics

General

Clinical Characteristics

• Depression, muscle weakness, partial paralysis, dyspnoea, subcutaneous oedema of the feet, ataxia, thirst, prostration, convulsions, death (B15, B16.19.w1, B36.47.w47).
• May be associated salt encrustation of the feathers (J1.23.w3).
• In experimentally exposed ducklings, lethargy, loss of appetite, increased thirst, eye fatigue, heavy nasal secretions, salt encrusted on bill, fluid droppings, decreased growth rate and longer time to fledging. Weight loss, coma and death with higher concentrations (J1.24.w1, J1.24.w2, J40.55.w2, J50.108.w1).
• In experimentally-exposed ducklings Mottled ducklings Anas fulvigula: lethargy, loss of appetite, eye fatigue, heavy nasal secretions, decreased growth rate, deaths with higher concentrations, increased mortality with exercise, and longer time to fledging in survivors (J40.55.w2).

• Initial somnolence, lameness in one front foot, cool ears and extremities, reduced rectal temperature (37.1 °C). (J151.16.w1)
• Developing locomotory incoordination and "colic pains". (J151.16.w1)
• Terminal "symptoms of suffocation", death. (J151.16.w1)

Incubation

Mortality / Morbidity

• Poisoning of a young Elephas maximus - Asian Elephant was fatal. (J151.16.w1)
• Mortality of a number of elephants was reported from a single incident in the wild in Africa. (B385.4.w4)

Pathology

• Dehydration, excessive mucus in proventriculus, sloughing of gizzard lining, reddening of the brain surface, visceral gout, small hemorrhages on the viscera, hepatocellular vacuolation and renal tubular degeneration may be found. Blood may be dark and thick. High brain sodium level (J1.23.w3, B15, B36.47.w47).
• In ducklings: emaciation, enlarged salt glands and adrenals, reduced thymus, reduced trabecular bone in femur, changes in serum electrolytes. Only emaciation when death occurred after a short time of exposure to saline (J1.24.w1, J1.24.w2, B15).

Histopathology:

• Liver - diffuse vacuolation
• Kidney - tubular degeneration; accumulation of proteinaceous debris in collecting ducts.
• Spleen - congestion
• Brain - congestion
• Adrenals - intracytoplasmic vacuolation in glandular tissue
• Gastro-intestinal tract - increased cellularity of lamina propria

(J1.23.w3)

• General: Ascites (light), haemorrhagic diathesis. (J151.16.w1)
• Cardiac: Hydropericardium. (J151.16.w1)
• Renal: Kidneys oedematous. (J151.16.w1)
• Gastrointestinal: "striking water content." (J151.16.w1)
  • Liquid content of the small intestine and caecum had a salt (NaCl) content of 5.86%; the salt content of firm colon contents was only 0.33% NaCl. (J151.16.w1)
• Lymphatic: Lymph nodes oedematous. (J151.16.w1)

Human Health Considerations

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

• Canada geese Branta canadensis, snow geese Anser (Chen) caerulescens, Ross's goose Anser (Chen) rossii, common merganser Mergus merganser, lesser scaup Aythya affinis (J1.23.w3).
• Geese, ducks, Australian shelducks Tadorna tadornoides, Northern shovelers Anas clypeata (B15).
• Australian grey teal Anas (gibberifrons) gracilis (experimental) (J7.23.w1).
• Mallard Anas platyrhynchos ducklings (experimental) (J1.24.w1, J1.24.w2).
• American black duck Anas rubripes, mallard Anas platyrhynchos and hybrid (Mallard x American black duck) ducklings (experimental) (J50.108.w1)
• Mottled duck Anas luzonica ducklings (experimental) (J40.55.w2).

Elephants:

• Loxodonta africana - African Elephant in a single incident reported from the Sudan. (B385.4.w4)
• A young Elephas maximus - Asian Elephant, having eaten food which (due to a manufacturing fault) contained 9.29% sodium chloride. (J151.16.w1)

Host Species List

• Anas clypeata - Northern shoveler
• Anas gracilis - Grey teal
• Anas luzonica - Philippine duck
• Anas platyrhynchos - Mallard
• Anas rubripes - American black duck
• Anser caerulescens - Snow goose
• Anser rossii - Ross's goose
• Aythya affinis - Lesser scaup
• Branta canadensis - Canada goose
• Mergus merganser - Common merganser
• Tadorna tadornoides - Australian shelduck

Mammals:

• Elephas maximus - Asian Elephant
• Loxodonta africana - African Elephant

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

• Canada geese Branta canadensis, snow geese Anser (Chen) caerulescens, Ross's goose Anser (Chen) rossii, common merganser Mergus merganser, lesser scaup Aythya affinis (J1.23.w3).
• Geese, ducks, Australian shelducks Tadorna tadornoides, Northern shovelers Anas clypeata (B15).

Elephants:

• Loxodonta africana - African Elephant in a single incident reported from the Sudan. (B385.4.w4)

Host Species List

• Anas clypeata - Northern shoveler
• Anser caerulescens - Snow goose
• Anser rossii - Ross's goose
• Aythya affinis - Lesser scaup
• Branta canadensis - Canada goose
• Mergus merganser - Common merganser
• Tadorna tadornoides - Australian shelduck

Mammals:

• Loxodonta africana - African Elephant

General Information on Environmental Factors/Events and Seasonality

• Salt poisoning could occur anywhere that waterfowl birds use saline environments. However, it is most likely to affect migratory waterfowl in late autumn (fall), after several months on freshwater, when cold weather freezes fresh water, leaving only saline waters ice-free.
• A sudden temperature drop may also promote salt crystallization, which can lead to salt encrustation; this can prevent birds flying to fresh water.
• High winds may also be a factor increasing salt encrustation.
• The use of salt to keep roads ice-free could also provide saline puddles in winter.
• As ducklings and goslings have undeveloped salt glands and are unable to fly to reach fresh water, breeding on saline waters would only be possible if a fresh water source is available or the downies can be led to fresh water soon after hatching.

(J1.24.w2, J1.23.w2, J1.23.w3, B15, B16.19.w1, B36.47.w47). 

In Elephants:

• Apparent salt toxicity was reported in wild elephants during a very severe drought in which the only water available was from "very salt springs, and as these dried up they poisoned the elephants." (B385.4.w4)

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

• In waterfowl: Australia, USA, Canada (B15).
• In elephants: Sudan. (B385.4.w4)

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

• In waterfowl: Australia, USA, Canada. (B15)
• In elephants: Sudan. (B385.4.w4)

General Information on Investigation / Diagnosis

• Diagnosis may be difficult. Recorded presence of saline water and absence of available fresh water is suggestive, as are salt encrustation, inactive salt glands and post mortem examination findings indicating dehydration, but no evidence of trauma, other toxin or infectious disease, and recovery of individuals when given access to fresh water.
• Concentration of sodium in the brain of greater than 1800ppm has been suggested as a diagnostic indicator.
• Plasma or serum could be tested and compared to 'normal' controls for levels of sodium, chlorine and osmolarity, as these are normally maintained within close limits by homeostatic mechanisms and are increased in salt poisoning.

(J1.23.w3, B15, B36.47.w47)

• Post mortem findings, including high salt content of the intestinal contents. (J151.16.w1)
• A high salt content (9.29% NaCl) was found in the elephant's pelleted food (presumably due to a manufacturing mistake). (J151.16.w1)

• History & Documentation
• Physical Examination - General
• Physical Examination of Mammals
• Necropsy - General
• Necropsy of Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

Similar Diseases (Differential Diagnosis)

Specific Medical Treatment

• Treatment and Care - General

General Nursing and Surgical Techniques

• Removal from saline water and provision of access to fresh water. (J1.23.w3)

• Symptomatic treatment was given. (J151.16.w1)

• Treatment and Care - General

Preventative Measures

--

Environmental and Population Control Measures

WATERFOWL

• Birds that are on highly saline lakes may be hazed to freshwater areas, if such areas exist nearby.
• Road salt should be used sparingly and should be stored out of reach of wildlife.
• Management practices that may expose birds to compounds that interfere with salt gland function, such as applications of organophosphorus and carbamate pesticides, should be avoided and, if such practices are necessary, should be scheduled to allow arriving birds maximum time to adapt to saline environments.

(B36.47.w47)

• Environmental and Population Management - General
• Chapter 4 - B36 Field Manual of Wildlife Diseases - Disease Control Operations