Hypovitamonosis A in Aquatic Turtles

Overview

Hypovitaminosis A is a clinical condition of reptiles that results from a diet low or lacking in beta carotene (herbivores) and/or preformed vitamin A (carnivores and omnivores).

Etiology

Hypovitaminosis A occurs in reptiles fed a diet that is deficient in vitamin A. Chelonians seem to be the most susceptible but all reptiles need a dietary source of vitamin A. Two forms of vitamin A are available:

Animal-based retinol esters (preformed vitamin A):

• Retinyl acetate

• Retinyl palmitate

• Plant-based precursors:

• Beta carotenes

Diagnosis

The diagnosis of hypovitaminosis A can be met via dietary history, clinical signs, measuring vitamin A levels, or histopathology of tissue samples (squamous metaplasia of the epithelial surfaces).

Treatment

Supportive treatment should be utilized when there are clinical manifestations of vitamin A deficiency, and appropriate husbandry and dietary changes should be instituted. Vitamin A deficiency can be corrected by oral supplementation with vitamin A products or by offering small amounts of liver once per week. Injectable vitamin A should be used very cautiously, as hypervitaminosis A can occur with a single injection. We have found that 1500 to 2000 IU vitamin A is a safe parenteral dose for treating deficient animals. A single parenteral injection followed by dietary correction and oral supplementation is recommended. It is, however, important to recognize that other diseases can present with similar clinical signs (e.g., herpesvirus, mycoplasmosis) and that not every animal that presents has hypovitaminosis A.

Prognosis

Prognosis is good with early diagnosis, aggressive therapy, and appropriate husbandry changes. If evidence of metabolic disease such as renal disease (edema) and gout are present, the prognosis is more guarded.

References

• Divers, S. J., & Stahl, S. J. (Eds.). (2018). Mader's Reptile and Amphibian Medicine and Surgery-E-Book. Elsevier Health Sciences.