Vitamin A Deficiency in Waterfowl

Disease Summary

Alternative Names (Synonyms)

• Hypovitaminosis A
• Retinol deficiency

Disease Type

Infectious/Non-Infectious Agent associated with the Disease

Infective "Taxa"

Non-infective agents

• Vitamin A

Physical agents

References

Disease Author

Major References / Reviews

Code and Title List

Other References

Code and Title List

Detailed Clinical and Pathological Characteristics

General

Clinical Characteristics

• Growth retardation, muscular weakness, retarded growth of endochondrial bone, emaciation, ataxia, paralysis and death, also ruffled plumage, sinusitis, keratinization of third eyelid, conjunctivitis, pustular pharyngitis, pustular oesophagitis (B11.48.w6, B13.46.w1, B16.19.w1).
• White oesophageal plaques.
• Increased susceptibility to infections, and particularly bumblefoot, may be evident before other clinical signs of deficiency. Also linked to increased susceptibility to aspergillosis (J1.31.w5, B15, B35.13.w6).

Incubation

Mortality / Morbidity

Pathology

• Oesophagus: raised white nodules on mucosa, greatest in cranial portion , also in caudal portion, with fewest in central portion.

Histopathology:

• Oesophagus - squamous metaplasia of mucus-secreting glands, with severely affected glands dilated with keratin, cellular debris and bacteria. Keratosis in severely affected birds.
• Palatine salivary glands - squamous metaplasia in severe deficiency.

(J1.28.w2, J1.31.w5, B35.13.w5)

Human Health Considerations

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

• Mallard Anas platyrhynchos (J1.28.w2).
• American black duck Anas rubripes, mallard Anas platyrhynchos, Canada goose Branta canadensis (B15).
• White-eyed pochard (ferruginous duck) Aythya nyroca (J3.70.w1).

Host Species List

• Anas platyrhynchos - Mallard
• Anas rubripes - American black duck
• Aythya nyroca - Ferruginous pochard
• Branta canadensis - Canada goose

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

• Mallard Anas platyrhynchos (J1.28.w2).
• American black duck Anas rubripes, mallard Anas platyrhynchos (B15).

Host Species List

• Anas platyrhynchos - Mallard
• Anas rubripes - American black duck

General Information on Environmental Factors/Events and Seasonality

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

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

General Information on Investigation / Diagnosis

• Oesophageal lesions characteristic but may only be seen with severe deficiency.
• Serum retinol below 300µg/l is indicative of deficiency (liver level <2µg/g) but serum vitamin A level may be maintained higher despite relatively low liver stores. Hepatic level of retinyl palmitate of <2µg/g is definitely deficient.
• Oesophageal lesions may be seen at levels below 1.3µg/g liver (0.44 IU vitamin A/g liver).
• N.B. Vitamin A deficiency may be present despite moderate or good body condition.

(J1.31.w5, J1.31.w10).

• Physical Examination - General
• Necropsy - General
• 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

• Supplement diet with vitamin A (to level of 10,000-50,000 IU/kg feed) until signs disappear, then ensure diet contains normal recommended levels (B11.38.w6, B16.19.w1).
• Inadequate response to oral supplementation may occur. Single intramuscular injection 1-2,000 IU/kg body weight may be used (B34, B35.13.w6).

• Treatment and Care - General

General Nursing and Surgical Techniques

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Preventative Measures

WATERFOWL

• Ensure adequate vitamin A in diet: recommended levels for Pekin ducks are 8000 IU/kg feed (starter), 5000 IU/kg feed (grower/finisher), 10,000 IU/kg feed (breeder).
• Levels for birds generally vary from 2000 IU/kg for domestic chicks to 13,000 IU/kg for quail.

(B13.46.w1, B16.19.w1, B35.13.w5).

• Food and Feeding for Birds - General

Environmental and Population Control Measures

WATERFOWL

• Preventative Medicine for Birds - General
• Food and Feeding for Birds - General
• Environmental and Population Management - General