Dog Hypothyroidism Causes and Treatment

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Dog Hypothyroidism


Dogs in early stages of thyroid problems show very subtle and indistinct signs, such as lethargy, skin infections, hair loss, and weight gain. As such, many veterinarians misdiagnose hypothyroidism as something else, causing a lot of dogs to suffer from a variety of physical and behavioral issues.

According to Dr. Jean Dodds (author of The Canine Thyroid Epidemic), hypothyroidism in dogs has reached "epidemic" proportions.

But why are so many dogs suffering from this disease? What causes dogs to develop hypothyroidism?

This page first takes a look at the possible causes of this "epidemic". It then looks at the conventional treatment of hypothyroidism in dogs, as well as some herbal remedies which may be used as an adjunct to the conventional treatment.

Please also read in more detail the signs and symptoms of hypothyroidism in dogs.

Common Causes of Hypothyroidism in Dogs

Here are some common causes of canine hypothyroidism:

Immune Problem

Research shows that in most dogs, hypothyroidism is caused by problems in the dogs' own immune systems.

In fact, most cases of canine hypothyroidism (about 80%) are caused by a disease called autoimmune thyroiditis (also known as lymphocytic thyroiditis). This particular disease is an autoimmune disease.

This means that the dog's immune system has identified the thyroid glands as being something abnormal and it attacks and destroys them. Very often, several different areas in the body will be affected as a result, e.g. the skin, the thyroid, and the digestive system.

Thyroid Gland Atrophy

This condition is not fully understood by veterinarians - the one thing that is known in this condition is that the thyroid gland is being replaced by fat.

Excessive Inbreeding

According to Dr. Dodds, breeders have been inbreeding and line-breeding dogs for years in order to get certain physical and behavioral traits. This selective breeding may pass along a number of undesirable inherited conditions, such as autoimmune thyroiditis.


The use of certain medication can reduce the production of thyroid hormone.

For example, the use of corticosteroids for treatment of skin allergy or other inflammations can actually cause hypothyroidism. Also, phenobarbital (a common drug used to control seizures in dogs) can block thyroid hormone production.

Lack of Exercise

A lack of exercise will decrease the production of thyroid hormone.


As our dogs are being exposed to toxins more and more these days, they are more susceptible to autoimmune diseases such as hypothyroidism.

Toxins such as pesticides, food preservatives, household cleaning chemicals are the main culprits. Many holistic veterinarians now regard excess vaccines as a source of toxin intake as well.

Dog Collars

Some vets also say that using dog collars (instead of harnesses) may cause hypothyroidism.

The thyroid gland is located in the upper third of the neck, exactly where the collar actually pushes on the throat.

Imagine pressing on this gland day in and day out for several years. The gland will be traumatized and inflammation will result, which will then trigger the dog's own immune system to remove the inflamed thyroid cells. This eventually leads to hypothyroidism as the destruction of the thyroid cells leads to an adequate production of thyroid hormone.

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Can Hypothyroidism Be Prevented in Dogs?

Unlike diabetes, which can be prevented in most cases with proper nutrition, diet and exercise, there are unfortunately no clearcut preventive measures to reduce the risk of developing hypothyroidism in dogs.

However, proper diet and nutrition and the use of natural supplements will boost the immune system and keep the body in the best health possible.

Diagnosis and Conventional Treatment

To diagnose hypothyroidism, many veterinarians only test for T4 (thyroxine) blood levels in the dog patient. However, this is not enough to come to a definitive conclusion.

According to Dr. Dodds, a complete baseline thyroid profile should minimally include:

  • Total T4
  • Total T3
  • Free T4
  • Free T3
  • TgAA (thyroglobulin autoantibody)

She advises that if a dog shows signs of hypothyroidism, the dog parent should insist on a full thyroid panel and accurate interpretation by a skilled professional before ruling out a diagnosis of hypothyroidism.

Conventional treatment of dog hypothyroidism is thyroxine hormone replacement, which is given twice daily.

It is important to note that the pills should be given apart from meals (at least 3 hours after or 1 hour before meal) since some foods such as soy and calcium bind thyroxine and impair its absorption.

Dosage depends on the severity of the condition, as well as the age, weight, and lifestyle of the dog patient.

Once the hormone replacement treatment starts, it has to be continued for the rest of the dog's life. Dog hypothyroidism can easily be managed, but never truly cured.

Natural Remedies for Dog Hypothyroidism

If you prefer natural thyroid hormone to synthetic one, you can use natural thyroid extracts made from bovine or porcine thyroid glands. However, the dosage has to be adjusted because some of these products contain both T4 and T3 thyroid hormones.

Natural supplements such as herbs can also be used in conjunction with thyroid replacement therapy to enhance thyroid gland function. Note that usually these supplements cannot fully replace the need for hormone replacement, but they may lower the dosage required.

Dog with hypothyroidism may benefit from kelp because of its rich iodine content and high levels of other nutrient minerals and vitamins. However, too much iodine can be harmful to dogs!

Dr. Dodds has the following suggestions:

  • If you feed your dog a commercial dry food (kibble), do NOT supplement with kelp or other forms of iodine more than 3 times per week. The reason is, commercial foods are usually already fortified with high doses of iodine.
  • If you prepare your own food (either cooked or raw) for your dog, you can supplement with kelp or other forms of iodine every day, but be sure to follow the product guidelines and dosage.

Licorice root not only stimulates an unproductive thyroid gland, but also strengthens and balances the whole body.

Astragalus or Siberian Ginseng can help to improve the energy levels and can also prevent thyroid atrophy.

If other organs or parts of your dog are also affected, consider other herbs that are good for such organs. For example:

  • If your dog also suffers from dry and itchy skin, use herbs such as Oregon grape, burdock, and sarsaparilla.
  • If the digestive system is compromised, try dandelion root, or yellow dock.

An Effective Natural Herbal Product

This formula contains herbs such as kelp (bladderwrack), Gotu Kola, Ashwagandha root, and more. It encourages the production of thyroid hormone and supports healthy thyroid functions. In addition, it supports normal immune functions and helps promote and improve a dog's skin and hair coat.


Foods to Avoid if Your Dog has Hypothyroidism

If your dog has been diagnosed with hypothyroidism or even slightly lower levels of thyroid hormones, avoid these foods:

Cruciferous Vegetables

Cruciferous vegetables (e.g. broccoli, cauliflower, Brussels sprouts, kale, cabbage, etc.) contain goitrogens, which are substances that interfere with the production of thyroid hormones, and should be avoided if your dog has hypothyroidism.


Soy contains isoflavones that disrupt normal thyroid function.


Foods that contain gluten (e.g. wheat, barley, rye) should also be avoided.

Gluten is strongly associated with autoimmune diseases. As mentioned above, most cases of canine hypothyroidism are caused by autoimmune thyroiditis, which is an autoimmune disease.

If a dog with autoimmune thyroiditis eats foods containing gluten, his immune system will launch an attack on the thyroid gland, resulting eventually in hypothyroidism.

W.J. Dodds, The Canine Thyroid Epidemic (Dogwise Publication, 2011).
W.J. Dodds, D.R. Laverdue, Canine Nutrigenomics - The New Science of Feeding Your Dog for Optimum Health (Dogwise Publishing, 2015).
Dr. Jean Dodds Pet Health Resource.

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