Canine Hypothyroidism Explained

Canine hypothyroidism is an endocrine disorder in which your dog's thyroid doesn't produce enough hormones.

Canine Thyroid and Its Role in the Body

Your dog's thyroid plays an important role in his body. The thyroid hormones are vital to his metabolism and help to regulate almost all of his body systems. For this reason, canine thyroid dysfunction can result in a range of systemic symptoms.

Usually, dogs who suffer from unexplained weight gain, hair loss and skin problems are suspected candidates for canine hypothyroidism. This is especially true if the problems are chronic and recurrent. Most dogs respond readily to treatment with a synthetic thyroid hormone like Soloxine.

Causes of Hypothyroidism in Dogs

Hypothryoidism occurs when the thyroid glands no longer function correctly. The pituitary gland, the hypothalamus and the thyroid gland all play a role in the production of thryroid hormones. A dysfunction in any of these glands can result in hypothyroidism, though 95% of all cases of canine hypothyroidism are caused by an impairment or damage to the thyroid gland.

Mid-size to large breed dogs between the ages of four and ten are most often affected, though some cases of congenital hypothryoidism have occurred in puppies. While there doesn't seem to be a sex-based predilication for the development of this disease, spayed females develop hypothryoidism more frequently than intact ones. Some breeds may be more disposed to developing the condition, including:

  • Golden Retriever
  • Doberman Pinscher
  • Irish Setter
  • Miniature Schnauzer
  • Dachshund
  • Cocker Spaniel
  • Airedale Terrier

Symptoms of Hypothyroidism

Thyroid hormones are essential to your dog's metabolic function. Without them, or without enough of them, all of your dog's organ systems could suffer. Because thyroid hormones affect so many of your dog's body systems, the symptoms of thyroid dysfunction are often variable and non-specific. Here are some of the symptoms of hypothyroidism in dogs:

  • Lethargy and mental dullness
  • Hair loss
  • Weight gain or obesity
  • Dry coat and excessive shedding
  • Hyperpigmentation of the skin
  • Cold intolerance
  • Slow heart rate
  • High blood cholesterol
  • Anemia

Diagnosis of Canine Hypothyroidism

Your veterinarian will need to perform a blood test to verify a diagnosis of hypothyroidism. The most common is the baseline T4 test, which tests the levels of the thryoid hormone T4 in your dog's blood. Only the thyroid gland produces T4, so dogs with a damaged or impaired thyroid gland will have lowered levels of this hormone in their bloodstreams.

Your vet may also use the TSH Level test to determine thyroid function. If your dog's thyroid is malfunctioning, the body will produce more TSH, or thyroid stimulation hormone, in an effort to stimulate the damaged or impaired gland.

Treating Hypothyroidism in Dogs

A dog with hypothyroidism will need to be on medication for the rest of his life. However, the symptoms usually begin to resolve themselves as soon as treatment begins. Treatment for hypothryoidism is simply a matter of administering a synthetic thyroid hormone. Your vet may need to tinker with the dosages quite a bit at first to get them just right.

Once your dog's dosages are correct, there's no reason he can't live a healthy, normal life.