Research overview: thyroid pathology in feline hyperthyroidism

The overwhelming majority of feline hyperthyroidism results from benign adenomatous hyperplasia or adenoma of the thyroid gland, frequently involving both lobes, with only a small minority caused by malignant thyroid carcinoma. Researchers have studied the molecular and cellular changes underlying autonomous hormone production, including alterations in signaling pathways that drive cells to function independently of normal regulation. This overview compiles the pathology literature rather than one source, describing the typical benign nature of the disease, why bilateral involvement affects surgical planning, and how understanding the cellular basis informs both treatment choice and investigation of causes. It matters because the predominantly benign pathology underlies the generally excellent prognosis with appropriate treatment, while the molecular changes offer clues to why the disease develops in aging cats.