EVIDENCE FOR ADRENAL DYSFUNCTION CONTRIBUTING TO PERACUTE MORTALITY SYNDROME IN RED PANDA (AILURUS FULGENS).

Red pandas (Ailurus fulgens) are endangered with extinction due to deforestation and habitat fragmentation. Reported causes of unexpected death in managed red pandas include kidney, liver, gastrointestinal, and cardiac disease. A previously undetailed syndrome, red panda peracute mortality syndrome, may be emerging, as red pandas have died unexpectedly, with no clear cause of death identified at necropsy. This case series describes the clinical and postmortem findings of five red pandas at Brookfield Zoo with abnormal adrenal size and associated histologic lesions as possible contributing factors to acute death. Antemortem clinical signs consisted of thin body condition, vomiting, intermittent diarrhea, neck ventroflexion, ataxia, and electrolyte abnormalities. Mortality may have been due to abnormal adrenal function, resulting in fatal electrolyte disturbances. Antemortem adrenocorticotropic hormone (ACTH) stimulation tests indicated an inappropriate response to ACTH with persistently low cortisol and aldosterone levels after cosyntropin administration. Clinical improvement was seen when red pandas were provided steroids, but all cases were eventually fatal. Further study is needed to understand red panda peracute mortality syndrome and associated adrenal dysfunction.