Hypothyroidism in Dogs

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The thyroid gland is part of a dog's endocrine or hormonal system. The hormones that the gland produces are essential for normal metabolism and growth. When a dog's body produces lower than normal amounts of thyroid hormone, the disease hypothyroidism is the result. Hyperthyroidism or the overproduction of thyroid hormone is very rare in dogs.

"Hypothyroidism treatment is generally very effective and not too costly."

Hypothyroidism is most commonly diagnosed in middle-aged or older, large breed dogs. The disease usually develops after an abnormal immune reaction destroys the thyroid gland, although other causes are possible. Hypothyroidism in puppies usually occurs because of improper development of the thyroid gland.

The Signs of Hypothyroidism

Dogs that develop hypothyroidism as adults typically have one or more of following symptoms:

  • Lethargy
  • Depression
  • Weight gain
  • Exercise intolerance
  • Thin coat and poor hair growth
  • Recurrent skin problems, including infections
  • A preference for warm versus cold parts of the home

In severe cases, hypothyroid dogs can develop neurological problems or may even become comatose. Ruptured cruciate ligaments and other musculoskeletal problems are also more common in hypothyroid dogs. Puppies that have low thyroid hormone levels have stunted growth.

Hypothyroidism Treatment Options


If you suspect that your dog has hypothyroidism, take him to the veterinarian. He or she can take a sample of blood and determine whether the amount of circulating thyroid hormone is normal or low.

Evaluating the results of these blood tests can be complicated, however, because thyroid hormone levels often decrease when a dog is sick for any reason. Therefore, low thyroid hormone levels alone should not automatically lead to a diagnosis of hypothyroidism. To be accurately diagnosed with primary hypothyroidism, your dog should:

  • have several of the common symptoms associated with hypothyroidism,
  • have low levels of thyroid hormone, and
  • the presence of other diseases needs to been ruled out via blood work, a urinalysis, fecal examinations and possibly other diagnostic tests.

If routine testing for hypothyroidism is inconclusive, additional lab work that evaluates thyroid function may be necessary.

Thankfully, hypothyroidism treatment is much easier than its diagnosis. Several companies make an oral synthetic thyroid hormone, but the most consistent results are usually seen with the brand name Soloxine. Treatment is generally very effective and is not too costly, although most hypothyroid dogs do need to receive their thyroid pills twice a day for the rest of their lives.

Routine monitoring of a dog's thyroid hormone levels is also important to make sure that his dose remains appropriate. Follow your veterinarian's instructions regarding how to schedule these rechecks around the times when you normally give your dog his pills. Taking a blood sample at the wrong time makes interpreting the results very difficult.

The above is provided for information purposes only and should not be used for the diagnosis or treatment of any condition. This information does not cover all possible variables, conditions, reactions, or risks relating to any topic, medication, or product and should not be considered complete. Certain products or medications may have risks and you should always consult your local veterinarian concerning the treatment of your pet. Any trademarks are the property of their respective owners.

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