Functional thyroid gland adenoma in a dog treated with surgical excision alone.

An 11-year-old male Golden Retriever presented with progressive weight loss, tachycardia, hyperthermia, polyuria and polydipsia. A freely movable mass, 4.5 x 4 cm in size, was palpated at the cranioventral cervical region. Hormonal study revealed high levels of serum thyroid hormones, and a tentative diagnosis of hyperthyroidism due to a thyroid tumor was made. The tumor was removed surgically and diagnosed histopathologically as thyroid gland adenoma. Serum thyroid hormone levels decreased after surgery with improved clinical signs. At 12 months after surgery, the dog maintained a good physical condition with no evidence of recurrence.