May 17, 2022



A Guide to Hypothyroidism in Dogs

Hypothyroidism in Dogs

Hypothyroidism is the most common thyroid disease in humans, affecting over 10 million Americans. Chances are you or someone you know suffers from an underactive thyroid

But did you know your four-legged canine might also be at risk?

This common endocrine disease occurs when your dog's thyroid isn't producing enough essential thyroid hormones to regulate their metabolism. As a result, their metabolism slows down. 

Dogs at risk for hypothyroidism 

Just like in people, hypothyroidism can affect any dog at any age. However, it is often found in middle-aged dogs (4-10 years old)

Medium-to-large-size dog breeds also appear to be at greater risk of developing the disease than others. These breeds include:

Though the reasons aren't entirely clear, spayed and neutered dogs have an increased risk of developing hypothyroidism. 

Signs and symptoms of hypothyroidism in dogs

There are several signs a dog may exhibit that could indicate he has thyroid disease. 

Symptoms of hyperthyroidism in dogs include, but are not limited to:

  • Unexplained weight gain

  • Obesity

  • Increased thirst

  • Increased urination

  • Enlargement of the thyroid gland

  • Vomiting

  • Diarrhea

  • Aggression 

  • Slowed heart rate 

  • Lethargy

  • Decreased activity level

  • Anemia

  • Muscle weakness

  • Cold intolerance

  • Dull, thinning coat

  • Hair loss

  • Hyperpigmentation

  • Recurring ear or skin infections

If your dog shows any of these symptoms, consult your vet as soon as possible. 

Causes of hypothyroidism in dogs

Lymphocytic thyroiditis (inflammation of the thyroid gland) and idiopathic thyroid gland atrophy (degeneration of the thyroid gland) are the two common causes of hypothyroidism in dogs. 

Though less common, dogs can also develop hypothyroidism due to:

Diagnosing a dog with hypothyroidism 

According to The Merck Veterinary Manual, hypothyroidism is one of the most over-diagnosed diseases in dogs because it shares many similarities to other diseases. Therefore, diagnosing can be tricky. 

Your vet will look at your dog’s clinical symptoms and run some diagnostic tests. A test that measures your dog's T4 concentration levels is often a good indicator of hypothyroidism. However, the vet may perform other blood and hormone tests as well. 

Hypothyroidism treatment options for dogs 

Treatment for hypothyroidism includes a prescription medication called levothyroxine, a synthetic form of the thyroid hormone your dog is missing. 

Since hypothyroidism is treatable but not curable, your dog will need to stay on their thyroid replacement hormone for life. Your dog may require adjustments to their dosages from time to time, so it's recommended you have their blood thyroid levels checked by your vet at least yearly. 

In addition to medication, your dog should also have a healthy diet that includes amino acids, iodine, vitamins, minerals, probiotics, antioxidants, proteins, fats, and carbohydrates. Your vet can recommend the best food to feed your dog with hypothyroidism. 

Final thoughts 

Every organ in your furry friend's body is affected by their thyroid hormone and metabolism. As a result, untreated hypothyroidism can shorten your dog's lifespan and lead to overall lower quality of life. Untreated hypothyroidism in dogs can also lead to:

You don't have to go into debt paying for your dog's hypothyroidism medication or other pet prescriptions. By doing a little bit of research, cost comparison inquiries, and using CareCard, you can save money on pet medications. 

Subscribe to Our Newsletter

You will receive a free pharmacy discount card when you subscribe.

By subscribing to the newsletter you agree with our Privacy Policy
Pharmacy names, logos, brands, and other trademarks are the property of their respective owners. Prescription savings may vary by prescription and by pharmacy, and in some cases may be discounted up to 85% off cash price*. Please note, this is NOT insurance. CareCard offers you the opportunity to find prescription discount prices, which ultimately depend on the provider. You are fully responsible for paying for all health care services but will be entitled to receive a discount from those health care providers in accordance with the specific pre-negotiated discounted rates. CareCard Inc. is not sponsored by or affiliated with any of the pharmacies identified in its price comparisons. This information is not mean to be a substitute for professional medical advice, treatment, or diagnosis. For additional information, please reach our customer support at 1-866-410-1217, Mon- Friday 9am – 5pm Est or email us at By using the CareCard prescription discount card or service, you are agreeing to CareCard’s Terms of Service.

Get the CareCard Mobile App

App Store linkApp Store link
LegitScript approved