Dog hyperthyroidism, an owners guide to hyperthyroidism in dogs

Thyroxine is a hormone which is secreted by the thyroid gland. Hyperthyroidism in dogs is a condition that occurs when the gland overproduces thyroxine. It is a rare condition for dogs. When it does occur, it normally affected middle-aged and old dogs.


Dog hyperthyroidism is usually brought on by cancer of the thyroid gland. The cancer prompts the growth of a tumor, which will prevent the gland from functioning properly. This in turn causes the gland to overproduce thyroxine.


Hyperthyroidism in dogs is a slow, progressive disease which can affect many organ systems. Virtually all dogs with this condition suffer weight loss. Most dogs will eat more than usual, but some will eat less.

This disease causes many dogs to experience hyperactivity. For others, it’s the complete opposite as they will appear lethargic. Other common symptoms include increased urination, weakness, and increased heart rate.


The veterinarian will start out by performing a physical exam. This will allow him to check for an enlarged thyroid gland and elevated heart rate. Your dog will have to submit a blood sample to analyze with a variety of tests. Although this condition drastically changes the levels of thyroid hormones in the blood, the current level at the veterinarian’s office may be normal. Therefore, you may have to return in a few weeks to have it checked again.


Hyperthyroidism in dogs is a condition which can effectively be treated. Medications can be prescribed to control production of thyroid hormones. Another treatment option in surgery.

Surgery involves removing one or both thyroid glands, but this may lead to hypothyroidism instead. Hypothyroidism is a condition in which too few thyroid hormones are produced.