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Hypothyroidism in Dogs: What it is and How it's Treated

Updated: Mar 29

Hypothyroidism is a common disease in dogs, and while it can be concerning to learn that your dog has it, it is treatable. In this article, we will discuss what hypothyroidism is, what the thyroid gland does, and the different forms of treatment that your dog can receive going past their diagnosis.

What is the Thyroid?

The thyroid gland is a muscle located within your dog's neck near its voice box, and it is comprised of two separate lobes that sit on either side of the trachea. It is responsible for producing thyroxine hormones that control your dog's metabolism and temperature.

What Causes Hypothyroidism?

In most cases, primary hypothyroidism occurs due to gland destruction in over 90% of diagnosed dogs. There are two ways this can happen:

  • Thyroiditis: healthy thyroid tissue is lost due to a dog's immune system causing inflammation in the glands

  • Atrophy: Normal thyroid tissue is replaced by fat connective tissue

Other causes of hypothyroidism include cancer of the thyroid gland, disease in the pituitary gland, congenital defects, or external trauma to the thyroid.

Signs of Hyperthyroidism in dogs

Low thyroid levels in your dog affect all of their organs, and most of the symptoms that they display will relate to their slowing metabolism.

  • Hair loss (Alopecia)

  • Skin infection

  • Dull, dry coat

  • Skin thickening

  • Weight gain

  • Ear infection

  • Reduced activity level

  • Inability to tolerate cold

  • Anemia

Autoimmune Thyroiditis

Certain breeds of dogs are predisposed to a specific type of thyroid disease called Autoimmune Thyroiditis. This occurs when your dog's immune system attacks the healthy cells of the thyroid gland. This mostly occurs in specific breeds:

  • Akita

  • Doberman Pinscher

  • Beagle

  • Golden Retriever

Diagnosing Hypothyroidism in Dogs

It can be very easy to misdiagnose hypothyroidism because several illnesses and medications can reduce thyroid levels. Your veterinarian will diagnose your dog based on clinical signs and through careful diagnostic testing such as blood tests and thyroid level monitoring. It will most likely take several tests to confirm that your dog has hypothyroidism.

How it is treated

Hypothyroidism is treatable, but not curable. Dogs must be treated for life with thyroid hormone replacement therapy through a prescription of thyroxine, a replacement hormone compound. The dosage that your dog receives will vary depending on their weight and age, and your veterinarian will need to adjust the dosage over time to see what works. Once a stable dosage is found, your dog will need to be retested once or twice a year, receiving the same dose of medication for the rest of their life.


Hypothyroidism can be scary for your dog due to potential negative effects. If you believe your dog is showing any of the signs listed above, contact us at 559-434-5470 to learn more about hypothyroidism or book an appointment today.



  1. Hospital of Veterinary Medicine Washington State University. Hypothyroidism in Dogs

  2. American Kennel Club. Thyroid Disease in Dogs

  3. British Thyroid Foundation. Thyroid Disease in Dogs and Cats

  4. Cornell University College of Veterinary Medicine. Hypothyroidism

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