The Compendium North American Edition, 1991. 13(9): p.1399-1410.
HYPERTHYROIDISM is a common disease of older cats. I. Because of the apparent increased frequency of feline hyperthyroidism in recent years, practitioners should be familiar with the clinical presentation, diagnosis, and treatment of the disease. Feline hyperthyroidism results from excessive secretion of thyroid hormones. The disease is most often caused by a thyroid adenoma or adenomatous hyperplasia (approximately 98% of cats). Adenocarcinomas are present in 2% of affected cats and may metastasize. One or both lobes of the thyroid gland can be involved, and approximately 70% of cats have bilateral involvement.