HYPOTHYROIDISM IN A DOG AFTER SURGERY AND RADIATION-THERAPY FOR A FUNCTIONAL THYROID ADENOCARCINOMA

Hypothyroidism was diagnosed in a dog which had undergone unilateral t hyroid lobectomy and external beam irradiation (48 Gy in 3 Gy fraction s) for a functional cystic thyroid adenocarcinoma. Hypothyroidism beca me biochemically apparent within 4 months of completion of radiation t herapy, and clinically apparent within 7 months. Clinical signs resolv ed after thyroid hormone supplementation. The potential for alteration s in thyroid function should be considered in any animal undergoing ra diation therapy in which the thyroid gland is included in the radiatio n field. This potential may be greater if surgery and radiation are co mbined.