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Hyperthyroidism in Dogs - Signs & Symptoms

Hyperthyroidism in Dogs - Signs & Symptoms

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


What does the thyroid do?

Your dog's thyroid is responsible for producing a hormone called thyroxine (T4), as well as a host of other important hormones. Thyroid hormones play a key role in the regulation of your pup's metabolism and can cause serious health issues when the levels of these hormones are either too high or too low. If your pup's thyroid is producing too much hormone, they will be diagnosed with hyperthyroidism. 

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 leads 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. When symptoms are evident they can include:

  • Weight loss
  • Gagging
  • Increased appetite
  • Increased urination
  • Vomiting
  • 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?

Diagnostic bloodwork analyzing thyroid hormone levels is the primary way that this condition is diagnosed in dogs, however, your vet may be able to feel a thyroid mass, or note an increased heart rate,  by conducting a simple physical examination of your pup.

What is the treatment for hyperthyroidism in dogs?

When it comes to hyperthyroidism in dogs, treatment may include surgery, chemotherapy, radiation therapy, and/or iodine therapy depending on the stage of the thyroid cancer, tumor size, and the extent to which nearby tissue is affected. Surgery to remove the thyroid tumor typically has the best outcome provided that the mass is freely movable, less than 4cm in size, and has not yet spread to other parts of your pet's body.

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?

When detected and treated early, the prognosis for dogs with thyroid carcinoma is good. With appropriate treatment, many dogs can go on to enjoy a good quality of life and a long survival time. 

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 think that your dog may be experiencing the symptoms of hyperthyroidism please contact our Charlotte vets

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