What You Should Know About Common Thyroid Problems In Dogs

| Published on May 12, 2018

Did you know that thyroid problems are fairly common in dogs? Do you know what symptoms to look for that could indicate that your dog is suffering from a thyroid problem? What type of problems can affect the thyroid, and how do those problems affect your dog as a whole? Here’s what you need to know about thyroid problems that your dog might face in his lifetime.

What does the thyroid do?

The thyroid is a gland in your dog’s neck that produces several important hormones, including levothyroxine (T4) and liothyronine(T3). These hormones control the metabolism in your dog’s body, which affects how they use nutrients that they consume. The AKC calls the thyroid the “thermostat of the body.” Too much of the thyroid hormones coursing through your dog’s body can cause weight loss, while too little can cause weight gain.

Underactive thyroid

The most common thyroid problem in dogs is hypothyroidism, or an underactive thyroid. This causes your dog’s metabolism to slow down and leads to weight gain, among other problems. Hypothyroidism is more common in dogs than other domestic animals, but it is easily treated with synthetic hormone injections.

What types of dogs are typically affected?

Hypothyroidism is more common in mid- to large-sized dogs. Specific breeds that are more likely to develop the problem include Doberman Pinschers, Irish Setters, Golden Retrievers, Great Danes, Old English Sheepdogs, Dachshunds, Miniature Schnauzers, Boxers, Poodles, and Cocker Spaniels. Spayed or neutered dogs between the ages of 4-10 are the most likely to develop an underactive thyroid.




-Mental dullness

-Unexplained weight gain, obesity

-Hair loss (alopecia)

-Excessive shedding

-Poor hair growth

-Dry coat

-Dry or sensitive skin

-Excessive scaling of the skin

-Recurring skin infections

-Intolerance to cold

-Decreased heart rate

-Exercise intolerance

How is it diagnosed?

Your vet will need to do a thorough exam of your dog and take note of his health history, including the recent symptoms that brought your dog in. Your vet will likely do a wide variety of tests including a complete blood count, biochemistry profile, urinalysis, and endocrine testing. The levels of T3 and T4 will tell the best story about whether or not your dog has an underactive thyroid gland. Hypothyroidism is frequently overdiagnosed, so your vet will likely want to run plenty of tests to rule out other problems that mimic – or even cause – hypothyroidism.


Thyroxine is a synthetic thyroid hormone that is prescribed to dogs with an underactive thyroid hormone. Your vet will determine the dose your dog should get. Your dog will need to get tested regularly to make sure he’s receiving an appropriate dose of thyroxine, and the dose may need to be tweaked off and on for the rest of his life.

Overactive thyroid

Hyperthyroidism is more common in cats, but it can occur in dogs. It occurs when a dog’s thyroid gland produces too much hormone and can result in weight loss and other symptoms. Thyroid carcinoma, a type of cancer, is usually the cause of hyperthyroidism in dogs.


-Weight loss

-Increased appetite or eating fast

-Frequent urination

-Excessive thirst

-Fast heart rate

-Nausea, vomiting, diarrhea

-Difficulty breathing

-Enlarged thyroid or bulge in the throat


-Dull coat

How is it diagnosed?

Similar to testing for hypothyroidism, your veterinarian will likely perform a wide variety of tests to rule out other causes for your dog’s symptoms or to verify the presence of thyroid carcinoma.


Medications are available to counteract the excess thyroid hormone to keep your dog comfortable, but treating thyroid carcinoma may involve radiation, chemotherapy, or surgery, although the long-term prognosis for dogs with a thyroid carcinoma is usually not very good.


Tumors on the thyroid gland may be either benign (harmless) or malignant (cancerous). Surgical removal may or may not be possible depending on where the tumor is located, whether it’s benign or malignant, how large it is, and how close it is to the esophagus and major arteries.




-Noticeable change in bark

-Round mass protruding from the throat area

-Decreased appetite

How are they diagnosed?

Your vet may prescribe imaging tests to get a better look at the tumor. A biopsy can help determine whether or not the tumor is cancerous. The combination of the biopsy and imaging should tell your vet what type of tumor is affecting your dog.


Common treatments for thyroid tumors include biopsy, surgical removal, medication, chemotherapy, or radiation.

(H/T: PetMD, Petful, AKC)

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