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What is hyperthyroidism in dogs?

Hyperthyroidism is a serious condition in dogs that develops if your pup's thyroid produces too much hormone. In today's post, our veterinarians explain more about the causes of hyperthyroidism in dogs and how it can be treated.

What does the thyroid do?

The thyroid gland in your dog is in charge of producing thyroxine (T4), as well as a variety of other important hormones. Thyroid hormones play an important role in the regulation of your pup's metabolism and can cause serious health problems if their levels are too high or too low. Hyperthyroidism is diagnosed when your dog's thyroid produces too much hormone.

What causes hyperthyroidism in dogs?

While becoming increasingly common in cats, hyperthyroidism is still relatively rare in dogs. When dogs do develop this condition it is a very serious health concern. Hyperthyroidism in dogs is typically caused by thyroid carcinoma (cancer). In the majority of cases, thyroid carcinoma in dogs is malignant and can grow rapidly.

What are the symptoms of hyperthyroidism in dogs?

The high levels of thyroid hormones caused by your pet's overactive thyroid lead to a dangerous increase in their body's metabolic rate. Many dogs will show no symptoms in the early stages of the disease, or perhaps just a lump on the underside of their neck. Signs of hyperthyroidism in dogs can include:

  • Weight loss
  • Gagging
  • Increased appetite
  • Increased urination
  • Vomiting
  • An increased amount of stool
  • Rapid heart rate
  • Enlarged heart
  • Facial swelling
  • Hyper-excitability
  • Difficulties swallowing
  • Increased thirst
  • Enlargement of the thyroid gland
  • Diarrhea
  • Congestive heart failure
  • Heart murmurs
  • Shortness of breath
  • Change in bark

How is hyperthyroidism diagnosed?

The primary way that this condition is diagnosed in dogs is through diagnostic bloodwork that analyzes thyroid hormone levels; however, your vet may be able to feel a thyroid mass or notice an increased heart rate by performing a simple physical examination on your pup.

What is the treatment for hyperthyroidism in dogs?

Depending on the stage of the thyroid cancer, tumor size, and the extent to which nearby tissue is affected, treatment for hyperthyroidism in dogs may include surgery, chemotherapy, radiation therapy, and/or iodine therapy. If the mass is freely movable, less than 4cm in size, and has not spread to other parts of your pet's body, surgery to remove the thyroid tumor is usually the best option.

If your pup's thyroid carcinoma is left untreated the tumor is likely to grow very quickly and spread to other parts of your pet's body.

What is the prognosis for dogs with hyperthyroidism?

Thyroid carcinoma in dogs has a good prognosis when detected and treated early. Many dogs can enjoy a good quality of life and a long survival time with proper treatment.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

If you suspect your dog might have hyperthyroidism, contact our Los Angeles veterinarians today.

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