Feline hyperthyroidism--a review.

Feline hyperthyroidism is the name given to the multisystemic manifestation of excessive concentrations of circulating thyroid hormones, thyroxine (T4) and tri-iodothyronine (T3). The most common cause is a functional thyroid adenoma involving one or both thyroid lobes. Both multinodular adenomatous hyperplasia and multinodular adenomatous goitre are acceptable descriptions for the histopathological findings. Thyroid adenocarcinoma rarely causes hyperthyroidism in the cat, and when present, seldom metastasizes. This is in contrast to the situation in the dog, where thyroid adenocarcinoma is aggressively malignant Grave's disease, an immune-mediated disease, and the most common cause of hyperthyroidism in man, was until recently thought not to occur in the cat. However, a recent study of 29 cats..