Canine Thyroid Adenocarcinoma

If you feel a lump in your dog's throat, located near his windpipe, take him to the vet as soon as possible. That lump could turn out to be canine thyroid adenocarcinoma, or cancer of the thyroid gland. Unlike some other canine lumps, thyroid tumors aren't usually benign.


Thyroid Adenocarcinoma

Your dog's thyroid glands sit on either side of his windpipe. They produce hormones that control the body's metabolism. Canine thyroid adenocarcinoma doesn't usually affect the actual production of thyroid hormones. That's fortunate, since too little or too much thyroid hormone throws the whole system out of whack. While the cause of canine thyroid cancer is unclear, it's more prevalent in areas deficient in iodine, since the thyroid needs this chemical to function properly.

Affected Breeds

While any dog might develop thyroid adenocarcinoma, some breeds are predisposed to the disease. These include the beagle, golden retriever and boxer. Thyroid cancer generally strikes dogs over the age of 9.


You might be able to see or feel the tumor lying over your dog's windpipe. His neck could swell up. Because the mass puts pressure on the windpipe, affected dogs might have difficulty breathing or swallowing, frequently cough or might sound hoarse when they bark. Other symptoms include frequent drinking and excessive urination, weight loss, vomiting and diarrhea.


Your vet might perform a fine-needle aspiration of the tumor, along with bloodwork. X-rays and ultrasounds to determine the size of the growth. Once diagnosed, ask your vet to recommend a board-certified veterinary oncologist to treat your dog. Not only do such vets specialize in cancer treatment, but they have access to more sophisticated diagnostic tools, such as nuclear scanning.


Treatment depends on the size of the tumor and whether or not it has spread. Small tumors are generally surgically removed. If that small tumor hasn't spread beyond the thyroid gland, surgery can be curative. If the tumor is large or has spread, your vet might recommend radiation or chemotherapy. Thyroid adenocarcinomas often metastasize to the lungs. In either case, it might be necessary to remove the thyroid gland. If that's the case, your dog requires lifelong daily thyroid medication.


According to the Oregon-based Portland Veterinary Specialists, dogs with small tumors might live three years or more with surgery. Since older dogs are generally affected, that's pretty much a normal lifespan. Dogs whose cancer has spread might live one to two years with treatment and quality care. For best results, offer him a quiet, low-stress environment.

By Jane Meggitt

About the Author
Jane Meggitt has been a writer for more than 20 years. In addition to reporting for a major newspaper chain, she has been published in "Horse News," "Suburban Classic," "Hoof Beats," "Equine Journal" and other publications. She has a Bachelor of Arts in English from New York University and an Associate of Arts from the American Academy of Dramatics Arts, New York City.