Diseases of the thyroid gland are common in many zoo species, but there are few descriptions of thyroid dysfunction in Mustelidae. A 7-yr-old, captive-bred female fisher (Martes pennanti) with progressive alopecia was diagnosed with clinical hyperthyroidism based on persistent elevation of both total and free serum thyroxine and triiodothyronine, ultrasound examination, and histologic evidence of adenomatous hyperplasia. Four additional geriatric adult fishers (two male and two female) were identified with thyroid adenomatous hyperplasia in a review of 23 postmortem records. Banked sera were available for thyroid hormone testing from three of the four necropsy cases. Total and free thyroxine were elevated in four of four animals tested, and triiodothyronine was elevated in two of three animals tested. Necropsy findings in four cases identified cardiac hypertrophy, congestive heart failure, and vascular lesions consistent with hypertension; complete tissues were not available from the remaining case. Clinical and subclinical hyperthyroidism may be a common but overlooked condition of captive fishers.

Oral eosinophilic granulomas were diagnosed in 16 tigers (Panthera tigris). All lesions were located on the hard or soft palate and typically consisted of flat or slightly raised circular ulcers. Histologic features of these lesions were essentially identical to those seen in oral eosinophilic granulomas of domestic cats and dogs. No clinical signs were noted in eight cases, though various degrees of inappetence, excessive salivation, and dysphagia were noted in the other eight tigers. Six cases were not treated. Treatment for the remaining 10 cases centered on corticosteroids and additional treatments included surgical removal, cryotherapy, antibiotics, and chlorpheniramine. Treatment with corticosteroids did appear to be effective in some cases, though lesions would worsen after cessation of therapy and no cases were cured. In addition, three cases developed complications possibly related to this corticosteroid therapy. The etiology of these lesions remains unknown, though an underlying allergic condition is likely.