Diagnosing Thyroid Cancer in Dogs

The thyroid cancer in dogs is a condition that affects the thyroid glands. The 2 thyroid glands are located in the neck area and help to produce the thyroid hormones, which help the dog's metabolism. Tumors on the thyroid glands are not common and can be benign or malignant. The diagnosis of the thyroid cancer can be done judging by the symptoms displayed by the dog and by performing a few additional tests.

Thyroid Tumors

Thyroid tumors are very rare in canines; however, if they occur these may be benign (adenoma) or malignant (carcinoma). The benign tumors may develop and cause an excessive production of thyroid hormones. The malignant tumors will not cause hormone production but they may stop the normal production of hormones and may also spread to the lungs or the lymph nodes.

Typically, the thyroid tumors are malignant in dogs. These tumors occur more frequently in middle aged or senior dogs. Certain breeds such as Boxers or Beagles are more prone to thyroid cancer.

Symptoms of Thyroid Cancer

The thyroid cancer may manifest through a wide range of symptoms. The most visible sign of a thyroid tumor is a large lump or swelling which is located in the neck area.

The tumor may also affect the hormone production and the dog may have hypothyroidism causing dry, flaky skin and dull coat.

The tumor may affect the dog in different ways, causing symptoms such as:

  • Coughing and breathing difficulties, caused by the touching of the windpipe or the occlusion of the air ways
  • Difficulties in swallowing, due to the fact that the tumor may press against the esophagus; this may also lead to excessive drooling and a lack of appetite
  • The dog's bark may change, the tome may be different if the tumor presses on the nerves in the voice box

Diagnosing Thyroid Cancer

If you notice any of the above mentioned symptoms, especially the abnormal swelling at the base of the neck, you should consult the vet. Let the vet know about the symptoms that you may have noticed in your dog. The thyroid cancer may be diagnosed through a vet examination.

The tests performed by the vet may include:

  • A complete blood count (CBC)
  • Urinalysis
  • X-rays in the neck and possibly chest area to determine if the lungs are affected
  • Ultrasounds
  • CAT scan, to determine if the tumor has spread
  • Thyroid hormone tests

However, the most conclusive test is the biopsy of the tumor that will establish if the lump is indeed a tumor. The biopsy will reveal the type of cells that form the tumor and whether the tumor is malignant.

Treatment for Thyroid Cancer

Ideally, the thyroid tumors must be removed, before they get the chance to attach themselves to other organs or affect the lymph nodes or the lungs.

If surgery is no longer possible and the cancer has evolved, the dog may receive chemotherapy, but the diagnosis will be poor.