Thyroid gland carcinoma in a bitch

Thyroid tumors are uncommon in dogs, accounting for 1% to 4% of all canine tumors. The average age of affected animals ranges from 10 to 15 years. The aim of this study was to report the case of a 12-year-old mixed-breed female dog named Pirata, treated at the Veterinary Hospital of the University of Porto. During the physical examination, a nodule in the left thyroid region was observed. Hematology, biochemical profile, thyroid profile, ultrasound, and fine-needle aspiration cytology were requested. The laboratory tests were within normal limits. A presumptive diagnosis of thyroid carcinoma was made, and staging performed through computed tomography revealed no metastasis, but the nodule was closely associated with the carotid artery. Therefore, chemotherapy with doxorubicin was chosen, with cycles administered every 21 days. The chemotherapy treatment did not lead to significant cytoreduction for surgical resection, and the dog surpassed the life expectancy but was euthanized due to worsening health conditions approximately 2.5 years after diagnosis.