Hypothyroidism in Dogs: Low Thyroid Symptoms, Diagnosis & Treatment

Published by Dr. Sarah Wooten
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If your dog has been extremely tired lately or has been having issues with their skin or hair, they could have hypothyroidism. Thankfully, thyroid problems in dogs are easy to diagnose and manage. While the exact cause of thyroid dysfunction in our canine companions isn't clear, we do know how hypothyroidism affects dogs and how to treat it.

What Is the Thyroid?

The thyroid, in dogs and in humans, is a butterfly-shaped gland located in the neck, right next to the windpipe. As part of the endocrine system, the thyroid gland makes the hormones necessary for cells to function normally. The thyroid affects the body's metabolism.

If a dog produces too much thyroid hormone, they can develop signs of hyperthyroidism, including diarrhea, increased heart rate, anxiety and hyperactivity. If the thyroid gland doesn't secrete enough thyroid hormone, you get the exact opposite — hypothyroidism. This is the most common thyroid problem and is sometimes referred to as having low thyroid in dogs.

Risk Factors for Hypothyroidism in Dogs

Hypothyroidism is most often diagnosed in dogs between 4 and 10 years old. In most cases, an autoimmune disorder that shrinks or inflames the thyroid tissue causes hypothyroidism in dogs. There are no known genetic causes and it is medium to large breeds that are at greater risk of developing thyroid issues, than toy and miniature breeds. Dog breeds such as the Cocker SpanielMiniature SchnauzerDachshundDoberman pinscherGolden RetrieverAiredale Terrier and Irish setter also appear more likely to develop the thyroid disease.

Snoozing dog with hypothyroidism

Signs of Hypothyroidism in Dogs

Hypothyroidism in dogs affects every system of the body, including the gastrointestinal system, the nervous system and the circulatory system. If a dog hasn't been spayed or neutered, hypothyroidism can also affect the reproductive system.

According to Vet West Animal Hospitals there are many clinical signs to look out for and most dogs with hypothyroidism have one of more of the following:

  • Weight gain without an increase in appetite
  • Lethargy and lack of desire to exercise
  • Cold intolerance
  • Dry, dull hair with excessive shedding and flaking
  • Very thin to nearly bald hair
  • Increased dark pigmentation in the skin
  • Increased susceptibility and occurrence of skin and ear infections
  • Failure to re-grow hair after clipping or shaving
  • High blood cholesterol

Further signs of low thyroid in dogs may also include:

  • Excessive tiredness
  • Mental dullness or depression
  • Excessively long heat cycles in female dogs who haven't been spayed
  • Generalized weakness and other neuromuscular problems
  • A stiff walk or loud breathing due to laryngeal paralysis (loss or normal function of the larynx)

How It's Diagnosed

The good news is that, unlike human thyroid problems, thyroid problems in dogs are usually easily diagnosed and managed. If you suspect your dog might be suffering from a thyroid problem, make an appointment with your pet's veterinarian. During the visit, the vet will ask you some questions, conduct an exam and will likely ask to run some lab tests which will most likely be blood work and urine testing in order to understand the health of your dog.

High blood cholesterol is a common indicator of hypothyroidism in dogs. Most clinics can also test for thyroid hormone levels in dogs with a simple blood test.

All this information together will build a picture for your vet so that they can determine whether or not your dog has hypothyroidism, and if so, what you can do from there in order to support your dog in the best way possible.

Treatment for Hypothyroidism in Dogs

If your dog is diagnosed with hypothyroidism, then please don't worry! Even though you can't cure hypothyroidism in dogs, it's usually quite easy and relatively inexpensive to manage with an oral thyroid supplement. The supplement mimics the effect of thyroid hormone on the body. If it's successful, your dog will regain their energy, lose weight, have a brighter attitude and stop shedding hair.

The key thing to remember when treating thyroid problems in dogs is the importance of balance. If your dog takes too much thyroid supplement, they can develop signs of an overactive thyroid, which is the opposite of what you want. If the vet prescribes your dog a thyroid supplement, it's important to follow all dosing instructions — don't change the dosage without talking to the vet.

After starting your dog on a thyroid supplement, the vet will likely ask you to return in a couple of weeks to get a follow-up blood test to make sure your dog's thyroid hormone levels are appropriate. Once their hormone levels are stable, the vet will probably want to check them once or twice a year. It is important that you make and attend these appointments in order to ensure your dog is getting the support they need through every stage of life.

Nutrition for Dogs With Hypothyroidism

Providing proper nutrition to a dog with hypothyroidism is an important part of supporting overall thyroid health. Dogs with hypothyroidism need to be supported by food that contains balanced levels of amino acids, iodine, probiotics for gut health, antioxidants and the right amount of calories that contribute to a healthy weight. Ask your vet for nutritional recommendations for your dog.

Low thyroid problems in dogs are common and can be easily managed. Even with a diagnosis of hypothyroidism, your dog can live a long, healthy and happy life.

Contributor Bio

Dr. Sarah Wooten

Dr. Sarah Wooten

Dr. Sarah Wooten graduated from UC Davis School of Veterinary Medicine in 2002. A member of the American Society of Veterinary Journalists, Dr. Wooten divides her professional time between small animal practice in Greeley, Colorado, public speaking on associate issues, leadership, and client communication, and writing. She enjoys camping with her family, skiing, SCUBA, and participating in triathlons.

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