Thyroid Carcinoma in Dogs

Thyroid carcinoma is commonly reported in older dogs, with a median reported age of 9 to 11 years. Golden retriever, beagles, boxers and Siberian huskies are reportedly predisposed. Most commonly, this disease is diagnosed because of the detection of a cervical mass by the owner or the referring veterinarian. This highlights the importance of neck palpation as part of every physical examination. Early detection and treatment of this cancer will result in a more favorable outcome.

Thyroid carcinoma is usually diagnosed by ultrasound- guided or palpation guided fine needle aspirate. This procedure is reportedly painful in humans and sedation for our canine patients is encouraged. Cytology may not be able to differentiate between an adenoma or adenocarcinoma. However, masses that present clinically are overwhelmingly malignant and a mass in the thyroid gland that is palpable should be treated as malignant, even in the face of a more bland cytology. An incisional biopsy by a Tru-cut biopsy is not recommended due to the high vascularity of these tumors and the high risk of uncontrolled bleeding or the potential for hematoma formation that might result in contamination of the area with carcinoma cells. Similarly, an open incisional biopsy is not recommended because of the high chance of hemorrhage and contamination of the biopsy tract. Technically, the removal of an entire lobe of the thyroid via a midline cervical approach is more straightforward than attempts at incisional biopsy over the mass laterally and this approach is not recommended.  [...]