The effect of supplementation with vitamin A on serum and liver concentrations in Puerto Rican crested toads (Peltophryne lemur) and its lack of impact on brown skin disease

“Brown skin disease” (BSD) is a clinical syndrome of dysecdysis, chronic weight loss and death, previously reported in Puerto Rican crested toads (Peltophryne lemur). Although vitamin A deficiency has been suggested, its cause remains unknown and multiple treatments have failed to prevent or reverse the condition. This study compared the efficacy of vitamin A supplementation, administered in different forms and by different routes, in 48 captive born Puerto Rican crested toads fed from metamorphosis on gut‐loaded, dusted, commercially raised crickets. Forty‐five toads started to show clinical signs of BSD at 9 months of age; all toads were treated orally with an oil‐based vitamin A formulation twice weekly for 2 months but continued to deteriorate. Two treatment groups were then compared: Animals in one group (n = 19) received 2 IU injectable vitamin A (Aquasol‐A) per gram bodyweight subcutaneously twice weekly for 3 months with no change in diet. Toads in the other group (n = 22) received a single oral dose of vitamins A, D₃, and E, and were fed on earthworms and crickets gut‐loaded with produce and a finely‐ground alfalfa‐based pellet, dusted with the same vitamin/mineral supplement. All affected animals developed severe BSD equally and died during, or were euthanized at the end of, the treatment regimen, with no clinical improvement. Animals supplemented with Aquasol‐A had significantly higher liver vitamin A concentrations compared with the other treatment group, whereas serum retinol concentrations showed no significant difference. Vitamin A supplementation does not appear a successful treatment once BSD symptoms have developed. Zoo Biol. 33:553–557, 2014. © 2014 Wiley Periodicals Inc.