Thyroidism in Dogs

Thyroidism refers to an abnormal function of the thyroid gland that can release either a smaller amount of hormones, resulting in a condition called hypothyroidism, or increased amounts of hormones, leading to hyperthyroidism.

Thyroid Problems in Dogs

The thyroid gland produces the thyroid hormones, namely the T3 and T4 hormones that play a significant role in the regulation of metabolism. When the level of T3 and T4 is low, the metabolism will be slow; when the level of these hormones is high, the metabolism will more rapid.

The rate of metabolism determines some basic functions of the body, such as:

  • the digestion
  • the weight
  • the heart rate
  • the skin and coat health

Hypothyroidism is more frequent than hyperthyroidism. A synthetic hormone replacement therapy can correct a deficit of thyroid hormones.

Canine Hypothyroidism

Canine hypothyroidism is a common disease, especially in middle-aged dogs. Certain breeds can develop hypothyroidism easier e.g. Golden and Labrador Retrievers, Doberman Pinschers, Beagles or Dachshunds.

Some frequent causes of hypothyroidism are:

  • Atrophy of thyroid glands
  • Lymphocytic inflammation (the antibodies produced to fight infection attack thyroid gland cells instead)

The thyroid hormones are necessary for normal cellular metabolic function. A deficiency of thyroid hormones affects the metabolic function of all organs. The disease has non-specific symptoms such as:

  • Weight gain without increase of appetite
  • Lethargy
  • Anemia
  • Dry hair and coat
  • Hair loss
  • Slow heart rate
  • High cholesterol
  • Hyperkeratosis (thick scales on the skin)
  • Hyperpigmentation (dark spots on the skin)

For the diagnosis of hypothyroidism several different tests can be done. Baseline T4 and BaselineT3 tests can be done to check the T4 and T3 hormone levels. If the diagnosis is suspected but not confirmed, additional tests will be needed. TSH and TRH stimulation tests, a serum total reverse T3 concentration test (radioimmunoassay) as well as a serum free T3 and T4 concentration test.

Canine hypothyroidism responds well to thyroxine treatment. The means of administration of this substance (pills or injections) will depend on the severity of the disease and the response of the body to the drug. Periodical checkups are required and the pill doses will be adjusted accordingly.

However, homeopathic remedies can also be used to help the function of your dog’s thyroid gland. Products that contain ingredients such as Fucus vesiculosisis, Astragalus membranaceous, Eleutherococcus senticosis, Urtica urens,  Zingiber or Nux vomica may be used in dogs with hypothyroidism.

Hyperthyroidism in Dogs

Hyperthyroidism involves the hyperactivity of the thyroid gland and it is not very frequent. There is a higher incidence in the Labrador Retriever breed. The disease is often caused by a thyroid cancer (carcinoma) or a growth that affects the thyroid glands.

Some symptoms of the disease are:

  • Increased heart rate
  • Increased appetite
  • Weight loss

The thyroid tumors are large and fast-growing. Treatment with Tapazol may be chosen but the surgical removal of the entire thyroid gland is necessary, followed by chemotherapy and radiation.