Understanding Hypothyroidism in Dogs

Understanding Hypothyroidism in Dogs

It is difficult to watch your animal companion struggle with health issues and not know what is causing them. With hypothyroidism in dogs, it can be tricky to see the underlying cause.

Some of the classic symptoms of hypothyroidism in dogs include:

  • Skin problems
  • Lack of energy
  • Weight gain
  • Sensitivity to cold
  • Behavioral changes

If you think your dog might have hypothyroidism, they need to be tested as soon as possible. Find out more about the symptoms of hypothyroidism in dogs and what to do if you suspect it. See the information below.

What is Hypothyroidism in Dogs?

The thyroid gland is a secretory organ located in the front of the neck. This butterfly-shaped gland is part of the endocrine system, and it plays an integral role in your dog’s metabolism. If the thyroid is not producing hormones at normal levels, it can throw your dog’s body out of balance.

When a dog has hypothyroidism, their thyroid gland is underactive and not producing enough thyroid hormones. This slows down their metabolism.  

What Causes Hypothyroidism in Dogs?

Hypothyroidism in dogs is usually related to autoimmune disorders. Primary hypothyroidism, which refers to a problem with the thyroid itself, accounts for most thyroid problems in dogs. It can be caused by the following:

Autoimmune Thyroiditis

This condition occurs when a dog’s body sees the thyroid gland and its hormones as a foreign invader. It triggers an immune response, which prompts an attack on the cells. This leads to redness of the thyroid tissue. It causes scarring that impedes the proper function of the thyroid.

Idiopathic Thyroid Gland Atrophy

A small percentage of dogs have hypothyroidism, which causes the normal thyroid tissue to mix with fatty soft tissue that deteriorates over time. When a condition is “idiopathic,” it indicates that there is no explanation for the condition.

Are Certain Dog Breeds Prone to Hypothyroidism?

While any breed of dog can be affected by hypothyroidism, some breeds may be more susceptible, including:

  • Afghan Hounds
  • Airedale Terriers
  • Boxers
  • Shar-Pei
  • Chow Chows
  • Cocker Spaniels
  • Dachshunds
  • Doberman
  • Bulldogs
  • Retrievers
  • Great Danes
  • Irish Setters
  • Kishu Inus
  • Miniature Schnauzers
  • Poodles


Medium to large breed dogs appear to be more prone to hypothyroidism than smaller dogs. Furthermore, both male and female dogs can develop hypothyroidism.

What Are the Symptoms of Hypothyroidism?

Symptoms of hypothyroidism in dogs may be challenging to determine. The condition does not often present with a set of apparent symptoms, and there are some things you have to watch out for. These include the following:

Skin Problems

Dogs with hypothyroidism may have itchy paws, leading to itching all over their bodies. The dog can eventually lose their hair, and have excessive shedding. Dandruff may also be present, along with darkened skin where the hair used to be, and a strong odor coming from the skin.

Hair loss can occur in the following areas:

  • Trunk
  • Back of the rear legs
  • Tail

Lack of Energy

If your once fun-loving, energetic dog suddenly does not want to exercise and prefers to sleep all day, they might be suffering from hypothyroidism. They may start to slow down on walks or not come when called.

Weight Gain

When there is decreased thyroid function, weight gain will occur. There is often no increase in appetite associated with hypothyroidism, either.

Thyroid hormones typically assist the body in the breakdown of fat. They also help the liver and the pancreas to metabolize the calories necessary to utilize energy. This function is interrupted when there are too few thyroid hormones, or due to reduced thyroid function. The dog’s body stores the calories, and it turns into fat.

Even if your dog has hypothyroidism and you cut down on their calories, they will still gain weight, because food is not the reason for the weight gain.

Sensitivity to Cold

The thyroid gland needs to function properly to burn calories and generate heat and energy. The hypothalamus is a function in the brain that sends a message to the pituitary gland to regulate body temperature.

The pituitary gland then communicates to the thyroid gland to raise or lower the number of thyroid hormones it is producing. If your dog’s thyroid is not supplying enough thyroid hormones, they can be sensitive to the cold.

Behavior Issues

There is a link between low or abnormal thyroid function and behavioral issues in dogs. Pet parents need to understand this and be patient with their pups.

Some of the behavioral issues that correlate with abnormal thyroid function include:

  • Moodiness
  • Erratic temperament
  • Depression
  • Fearfulness
  • Anxiety
  • Irritability
  • Seizure

Many pet parents do not know that low thyroid levels can trigger aggressiveness in some dogs. Often, they think that training or retraining their dog is the answer, when it is hypothyroidism causing the behavior.

Another issue that can occur is seizure activity. Dogs with hypothyroidism can suddenly start to have seizures. There may even be signs of aggressive behavior right before the seizure.

Some other health problems associated with of hypothyroidism in dogs:

  • Head tilting
  • Ear and toenail infections
  • High cholesterol
  • Slow heart rate
  • Anemia
  • Exercise intolerance
  • Muscle loss

These issues may occur in conjunction with the ones listed above. Finding out whether your pup has hypothyroidism is the next step.

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