Research Communications of the 24th ECVIM-CA Congress

Conflicts of interest: This study was supported by grants from the Swedish Research Council and the Foundation for Research, Agria Insurance Company. The concomitant occurrence of two or more endocrine tumors and/or hyperplasias, known as multiple endocrine neoplasia (MEN) is a well-known entity in humans. Multiple gene mutations have been identified. The two major forms are MEN1 and MEN2. In MEN1, the main affected organs are parathyroid, pancreas and pituitary gland. MEN2 occurs in 3 clinical variants: MEN2A, characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and primary hyperparathyroidism; MEN 2B, characterized by MTC, pheochromocytoma and additionally abnormalities; familial medullary thyroid carcinoma. In dogs and cats only a few cases have been reported and it is unknown whether hereditary MEN-like syndromes exist in these species. The aim of this study was to evaluate the prevalence of multiple endocrine tumors in dogs and cats at our institution, to identify possible breed and sex predispositions and to investigate similarities with the human MEN syndromes. Autopsy reports of dogs and cats from 2004 until 2014 were reviewed. Animals with at least two endocrine tumors/hyperplasias (ETH) were included. Autopsy reports of 951 dogs and 1155 cats were examined. 149 dogs had ETH affecting a single organ, 24 had multiple ETH; 123 cats had single ETH, 21 had multiple ETH. In dogs with multiple ETH, the most common breeds were West Highland White Terrier (WHWT, 3/24), Poodle, Golden Retriever, mixed-breed dogs (each 2/24). 14/24 were male (13 intact); 10/24 were female (10 neutered). Median age was 12 years (range 7-18). The most common combination was multiple testicle tumors of various types (4/24). The most common affected organs were the adrenals (18/24). Adrenal cortical adenomas/carcinomas/hyperplasias were mainly associated with pheochromocytomas (3/ 24), testicle tumors (3/24) and insulinomas (2/24). All 3 WHWTs had adrenal adenomas. Both Poodles had pheochromocytoma associated with pituitary adenoma or adrenal hyperplasia. 2 dogs showed tumor combinations similar to the human MEN1 syndrome: pituitary adenoma and insulinoma; pituitary adenoma and parathyroid hyperplasia. 19/21 cats were domestic short/long hair, 2/21 were Persians. 11/21 were male (7 castrated); 10/21 were female (9 neutered). The median age was 15.5 years (range 10-19). The most common affected organs were thyroid glands (18/21), combined mostly with lesions of parathyroid (10/21) and adrenal glands (7/21). None of the cats had combinations similar to the human MEN syndromes. The prevalence of multiple ETH in dogs and cats was 2.5% and 1.8%. MEN-like syndromes were extremely rare in dogs and non-existing in cats. No sex predisposition was observed. Possible breed predispositions need further investigations.