Vitamin A Deficiency/Toxicity

Etiology:  Vitamin A deficiency/toxicity is caused by nutritional imbalances in vitamin A.  Consumption of misformulated or improperly stored diets, as well as oversupplementation, can cause nutritional imbalances.

Incidence:  Incidence is low in laboratory rabbits.

Clinical Signs:  Signs of deficiency and toxicity are similar.  Both can result in poor conception rates with high frequency of resorptions and delivery of stillborn kits.  Kits are often weak, have slow growth rates, and have congenital abnormalities including cleft palate and hydrocephalus.

In deficient states, juvenile rabbits may have epithelial hyperkeratinization of the cornea (see photo) and esophagus.

In toxic states, juvenile rabbits may have slow growth and concurrent vitamin E deficiency and associated myopathy. Young adult to adult rabbits may have slow growth rates and growth plate and joint abnormalities.  There is one report of polyarthropathy with hyperostosis and ankylosis of various joints.

Diagnosis:  Diagnosis can be made by the presence of clinical signs, as well as assaying the liver and serum for vitamin A content.  Liver vitamin A levels > 300 µg/g are suggestive of toxicity.  Liver vitamin A levels < 30 µg/g are suggestive of deficiency.