A 9-year-old intact male German Wirehaired Pointer was referred to the Cornell University Hospital for Animals' Internal Medicine Service in October 2012 for further workup of clinical hyperthyroidism and a cranioventral cervical mass at the level of the larynx. Ultrasound and fine needle aspiration of the mass were consistent with an invasive thyroid tumor, and nuclear scintigraphy using technetium-99m confirmed it to be in an ectopic location. Due to the adherent nature of the tumor, complete surgical excision was not considered possible, and radioactive iodine therapy was pursued as an alternative treatment. This case report will discuss the clinical presentation, diagnostic workup, treatment, and prognosis of a functional canine ectopic thyroid carcinoma.