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Hypothyroidism in Dogs

By Maureen Ryan. June 15, 2012 | See Comments

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Hypothyroidism in Dogs

Having hypothyroidism isn't a life sentence of discomfort and weariness for your dog. Learn more here.

It’s always hard to watch a pet suffer. It can be even more difficult with a disease like hypothyroidism, which can cause physical pain in your dogs as well as changes in behavior, personality, and mood. But having hypothyroidism doesn’t have to sentence your pet to a life of discomfort and weariness. Proper medical treatment can help dogs with the disease regain their energy and playfulness while eliminating painful symptoms altogether.

Causes of Hypothyroidism in Dogs

Hypothyroidism is a result of too little thyroid hormones being produced and secreted by your dog’s body. This hormone deficiency happens because the thyroid gland is damaged. In most cases, a genetic autoimmune disease causes the problem, but in rare instances, other conditions, including thyroid cancer, can damage the gland and lead to hypothyroidism.

Dogs who inherit the genetic disease known as autoimmune thyroiditis (or lymphocytic thyroiditis) have a normal functioning thyroid at birth but begin to develop problems around middle age. Usually symptoms become noticeable at between 5 to 6 years of age.

Hypothyroidism Symptoms in Dogs

Unfortunately, hypothyroidism may go undiagnosed for long periods of time because the classic symptoms are similar to conditions that dogs experience with the onset of old age. The first and most common signs of hypothyroidism are loss of fur, a dull hair coat, and reduced activity. Symptoms vary, though, from dog to dog and could include any of the following as well: weight gain, mental dullness, fatiguing easily during exercise, not being able to tolerate cold temperature, thickening and scaling of the skin, skin infections, changes in skin pigmentation, ear infections or ear pain, and a condition called mucopolysaccharides in which dogs’ faces droop and give them what is sometimes called “tragic” face.

Some more serious symptoms including feeding problems, cardiovascular problems, changes in eyesight, and reproductive disorders can also occur with hypothyroidism, but these are usually rare.

Veterinarians may order blood tests for dogs who display significant signs of hypothyroidism. An initial blood test will measure your dog’s level of the hormone thyroxine (T4). If this is below average, additional blood tests will be done to confirm other hormone levels and if they too are low, your dog will most likely be diagnosed with hypothyroidism.

Treatment of Hypothyroidism in Dogs

Once your vet confirms that your dog has hypothyroidism, he will most likely start your pet on synthetic hormones such as Soloxine or Thyro-Tabs (L-Thyroxine). Your dog will usually start out taking the medication two times per day, but as symptoms such as excessive shedding begin to disappear, the vet may transition your pet to a once-a-day dosage. You should expect dogs with hypothyroidism to take this replacement hormone every day for the rest of their lives.

As part of hypothyroidism treatment, dogs usually have regular check-ins with the vet to ensure that they are receiving a balanced dose of hormones. This is important because dogs that get too much of the replacement thyroid hormones may develop hyperthyroidism. Signs of hyperthyroidism include weight loss, vomiting, diarrhea, hyperactivity, and excessive thirst. It can also lead to hypertension and difficulty breathing.

Your vet will probably suggest you bring your pet in twice a year so he can monitor your dog and continue helping you keep your pet living a full and satisfying life.

More on Keeping Your Dog Healthy

How a Healthy Dog Weight Can Prevent Disease
Large Dog Breed Health
10 Symptoms in Older Dogs You Shouldn't Ignore
The PetCareRx Healthy Dog Weight Tool
Small Dog Care


This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by,your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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