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Hypothyroidism in Dogs

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Hypothyroidism in Dogs _ Symptoms and Treatment _ ASPCA Pet Health Insurance _ border collie smiling into the camera

If your dog is suffering from weight gain, hair loss, and skin issues, hypothyroidism could be the underlying cause. Fortunately, this condition is not typically life-threatening for your dog and can often be managed with medication once it is diagnosed.

What is Hypothyroidism?

Hypothyroidism is an endocrine (hormone) disorder related to the thyroid glands, which are small glands in your dog's throat near the larynx or voice box. They have a number of important functions in the body, including producing hormones that help regulate metabolism. Hypothyroidism occurs when these glands do not produce enough thyroid hormone and cause your dog's metabolism to slow down. In other words, if your dog is diagnosed with hypothyroidism, that means your four-legged friend has an underactive thyroid.

There is another kind of thyroid disease rarely seen in dogs, but it is common in cats. This is hyperthyroidism, which happens when the glands produce too much thyroid hormone. In contrast to hypothydoidism, hyperthyroidism speeds up your dog's metabolism. It can cause side effects such as hyperactivity, restlessness, a rapid heart rate, panting, and, eventually, weight loss in spite of an increase in appetite.

Have a cat at home? Learn about hyperthyroidism and how it can affect your feline friend.

Dogs at Risk

Dogs of any age or breed can suffer from hypothyroidism, but it is more prevalent in medium to large-sized dogs, such as Doberman Pinschers, Golden Retrievers, and Irish Setters. It has not been reported as frequently in German Shepherds and mixed breeds. Hypothyroidism is typically diagnosed in middle-aged dogs from around 4 to 10-years-old.

symptoms of hypothyroidism in dogs _ woman hugging a dog

Signs and Symptoms of Hypothyroidism in Dogs

Symptoms of hypothyroidism in dogs can be subtle and hard to detect, especially in the early stages. Signs of hypothyroidism can include:

  • Weight gain with no other clear causes, such as eating more or exercising less
  • A change in the dog's voice
  • Dry, scaly, thickened, or discolored skin
  • A dull coat and loss of fur—you might notice bald patches or excessive shedding
  • Behavioral changes, such as depression or increased irritability

A low thyroid hormone level can also affect mental sharpness. It can make a normally alert and curious dog seem distracted or slow to respond to commands.

By being aware of the side effects of hypothyroidism in dogs, you will be able to keep a lookout for and catch this disorder before it progresses.

What Causes Hypothyroidism in Dogs?

Hypothyroidism can be due to a disease called autoimmune or lymphocytic thyroiditis, which causes the body's immune system to attack the tissues of the thyroid gland. This underlying disorder harms the gland, making it unable to produce enough thyroid hormone to support normal function.

Occasionally, certain medications such as steroids can also impact the production of thyroid hormones and lead to hypothyroidism. In addition, this condition can be caused by a neck injury that damages the thyroid and, thus, the thyroid function.

Diagnosis and Treatment

While hypothyroidism is not usually a life-threatening disorder, it can negatively impact your dog's quality of life, so it is important to visit your veterinarian for proper diagnosis and treatment.

During the visit, your veterinarian will typically ask about your dog's symptoms and conduct a full physical exam. A blood test can also be done to check the level of thyroid hormones called thyroxine (T4) and triiodothyronine (T3). Additional diagnostic tests may also be needed to rule out other clinical signs or illnesses and evaluate the overall health of your dog.

diagnosing and treating hypothyroidism in dogs _ elderly Boxer dog

Treating Hypothyroidism

Hypothyroidism cannot be cured, but it can be managed through thyroid medication. Dogs with this disorder are prescribed a thyroid hormone replacement called thyroxine that will need to be given for the rest of the dog's life. Follow-up blood tests can help ensure the dog is receiving the right dosage of the medication to regulate thyroid hormone levels properly. If you inadvertently give too much thyroxine, you can cause hyperthyroidism.

Tips to Give Your Dog a Pill

If your dog needs to take thyroxine or any other kind of medication in tablet form, it can be tough to get them to swallow it down. Here are a few ways to help your dog take a pill:

  1. Wrap it up – You can wrap the pill up in a bit of cheese or a piece of sliced turkey. Just make sure your dog doesn't eat the tasty "wrapper" and spit the pill out on the floor.
  2. Hide it in a meal – You can try hiding the tablet in a bowl of wet dog food. This technique works better for dogs who gobble up their food quickly. Slower or more discerning eaters might pick around the pill, which is why you should always watch to make sure the pill is eaten up.
  3. Coax it in – Have your dog sit in front of you and gently open their mouth. Carefully place the pill near the back of the throat and close the mouth. Lightly hold your dog's jaw shut until they swallow it down. Be sure to offer lots of praise for a job well done.

Get more tips on giving your dog or cat a pill.


There is no way to prevent hypothyroidism, but regular veterinary visits can help your dog's doctor diagnose conditions like this sooner rather than later.

It also helps to do everything you can to support your dog's well being. For instance, brush their teeth regularly, make sure they get a good dose of daily exercise, and feed them a nutritious diet of high-quality dog food. You can supplement their diet with a variety of safe people foods, such as bits of skinless cooked chicken, boiled sweet potato, and apple slices.* And of course, shower your four-legged friend with all of the love and attention they deserve!

Even with dog conditions that are non-preventable or that do not have a cure, there are still many treatment and medication options that will allow your dog to live a happy and healthy life. Just as each dog has their own unique personality, they may also have specific treatment options that work best for them. Be sure to talk with your veterinarian about which choices will work best for your canine companion.

* Reminder: Treats such as these should not make up more than 10% of a pet's caloric intake. Also, stomach upset may occur in pets who do not tolerate dietary changes well.

The information presented in this article is for educational and informational purposes only and does not constitute or substitute for the advice of your veterinarian.


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