What is Hyperthyroidism?

Your cat has two thyroid glands located in their neck. These glands play a very important role in regulating your cat’s metabolism. Some cats develop nodules in one (or rarely both) thyroid glands. Most nodules are benign (1-2% are malignant). These nodules are active, meaning they produce excessive amounts of thyroid hormone. This subsequently causes their metabolic rate to increase.

How did my cat get Hyperthyroidism?

Older cats (9 – 12 yrs old) are more frequently diagnosed with hyperthyroidism than younger cats. Studies have shown that large amounts of dietary iodine may be linked to hyperthyroidism in cats.

What is Hyperthyroidism?

Your cat has two thyroid glands located in their neck. These glands play a very important role in regulating your cat’s metabolism. Some cats develop nodules in one (or rarely both) thyroid glands. Most nodules are benign (1-2% are malignant). These nodules are active, meaning they produce excessive amounts of thyroid hormone. This subsequently causes their metabolic rate to increase.

How did my cat get Hyperthyroidism?

Older cats (9 – 12 yrs old) are more frequently diagnosed with hyperthyroidism than younger cats. Studies have shown that large amounts of dietary iodine may be linked to hyperthyroidism in cats.

Symptoms

Weight loss from an increased metabolism is generally the first sign that is noticed in hyperthyroid cats. You may also notice some of the other symptoms which include:

  • Ravenous appetite and weight loss
  • Restlessness
  • Cranky disposition
  • Increased vocalization, especially at night time

  • Increased thirst and urination
  • Periodic vomiting and diarrhea
  • Coat will appear dull and unkept
  • Anorexia (lack of appetite) can develop if the disease progresses without treatment

Symptoms

Weight loss from an increased metabolism is generally the first sign that is noticed in hyperthyroid cats. You may also notice some of the other symptoms which include:

  • Ravenous appetite and weight loss
  • Restlessness
  • Cranky disposition
  • Increased vocalization, especially at night time
  • Increased thirst and urination
  • Periodic vomiting and diarrhea
  • Coat will appear dull and unkept
  • Anorexia (lack of appetite) can develop if the disease progresses without treatment

How does my veterinarian diagnose Hyperthyroidism?

Your cat’s outward appearance and behavior will indicate to the veterinarian that there is a need for further diagnostics to determine if your cat has hyperthyroidism. Further diagnostic tests can include:

  • Bloodwork looking for an increase in thyroid levels. Most of the time this will be easily detected. However, additional testing may be necessary.

Hyperthyroidism can lead to secondary conditions such as high blood pressure and cardiomyopathy (heart disease). High blood pressure is caused by the increased pumping from the increased metabolism. High blood pressure can lead to detached retinas if left untreated. This also causes the heart muscle to thicken making it more difficult to pump blood throughout your cat’s body. Your veterinarian may want to perform other diagnostics (radiographs, ultrasound, ECG, blood pressure monitoring) to determine the overall health of your pet. Most of the secondary conditions can be treated with proper medication.

Prognosis

With proper monitoring and medications your cat can continue to live a normal life.

Prognosis

With proper monitoring and medications your cat can continue to live a normal life.

Treatment Expectations

Your cat will likely go through a lot of testing to properly diagnose their disease and determine your cat’s overall health. For the remainder of your pet’s life you will be giving daily medication oral or transdermal methimazole to treat your cat’s condition.

Your veterinarian may discuss switching your cat to a low iodine diet like Y/D made by Hills Veterinary Diets.

There are also radioactive iodine treatments that can be performed by a specialist if you and your veterinarian feel that your cat is a good candidate for this kind of treatment. This treatment may eliminate the need for daily medications. Surgery to remove the thyroid nodule was a treatment option in the past, but is rarely performed today.

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