Systemic hypertension in a dog with a functional thyroid gland adenocarcinoma

A 12-year-old 21.9-kg (48.48-lb) spayed female Alaskan Malamute with a long-term history of panting, polydypsia and polyuria, weight loss, hind limb weakness, and a decrease in appetite was evaluated for hypertension.

Use of Doppler sphygmomanometry revealed a systolic blood pressure of 250 mm Hg (mean value for 5 consecutive measurements). Palpation of the ventral cervical region revealed a fixed asymmetric mass in the area of the lobes of the thyroid gland. The portion of the mass on the right side was approximately 2 x 2 cm, whereas the portion of the mass on the left side was approximately 1 x 1.5 cm. Hyperthyroidism was diagnosed on the basis of high serum thyroxine concentrations. Thyroidectomy of both lobes of the gland was performed. Histologic examination revealed a bilateral, multilobulated, and encapsulated thyroid gland adenocarcinoma.

Thyroidectomy of both lobes of the gland was performed with clinical resolution of hypertension. The dog was treated postoperatively with chemotherapeutics, including doxorubicin and carboplatin, and external beam radiation. Calcium and thyroxine homeostasis fluctuated; however, the dog finally achieved concentrations within the respective reference ranges through the administration of calcitriol, calcium carbonate, and levothyroxine.

This report describes concurrent hypertension in a dog with a functional thyroid gland adenocarcinoma with subsequent return of blood pressure values to within reference ranges after thyroidectomy.