Primary hypothyroidism due to thyroid carcinoma in a feline

ABSTRACT: Hypothyroidism is rarely observed in cats. This article reports the case of a thirteen-year-old feline with one-year history bilateral cervical swelling that had majorly grown size two weeks prior to animal’s admission. The cat presented dysphonia, lethargy, weight gain, and constipation. On physical examination, hypothermia was observed, rectal temperature 36.5 ºC. Fine-needle aspiration cytology suggested thyroid neoplasia. serum levels total T4 stimulating hormone (TSH), along exclusion non-thyroid diseases, confirmed diagnosis hypothyroidism. first report hypothyroidism Brazil secondary neoplasia, classified as follicular-compact carcinoma by histopathology.