Hyperthyroidism in pets.

Hormones are pretty amazing little compounds. So much of our body’s functioning depends on a delicate balance of them. When something goes wrong with their production or interaction, though, the results can be disastrous. The foundation of many diseases in both pets and people, hormone issues can really wreak havoc on the body’s normal functioning. 

Thyroid hormone is a very important chemical messenger within the body of our pets. If too little is produced (hypothyroidism), trouble can occur. We also see hyperthyroidism in pets, where too much thyroid hormone is produced. Oakhurst Veterinary Hospital has the information you need to tell if your pet is having trouble with hyperthyroidism.

More About Thyroid Hormone

The thyroid gland is a bi-lobed, butterfly-like gland that lies in the neck, hugging either side of the trachea. It is solely responsible for secreting thyroid hormone into the bloodstream. 

Thyroid hormone is a very important component of the regulation of metabolism. The more thyroid hormone is produced, the higher the metabolic rate of the animal. 

Hypothyroidism, the condition in which too little thyroid hormone is produced, can be the result of a congenital defect, inflammation, or auto-immune processes that affect the amount of function thyroid tissue. Dogs are more often affected by hypothyroidism with it being quite rare in cats. 

Hyperthyroidism in pets, on the other hand, is typically the result of overactive thyroid tissue. This is often due to a benign (harmless) but functional tumor development within the gland. Hyperthyroidism is most typically diagnosed in cats. 

Symptoms of Hyperthyroidism in Pets

The symptoms of hyperthyroidism in pets are directly related to the higher metabolic effects of the overproduction of thyroid hormone. The most common symptoms include:

  • Weight loss
  • Ravenous appetite
  • Potential gastrointestinal symptoms like vomiting and/or diarrhea
  • Personality changes
  • Increased vocalization
  • Increased thirst and urination
  • Poor hair coat

While symptoms of hyperthyroidism in dogs are the same as those in cats, it is quite rare to diagnose. Most dogs affected by hyperthyroidism are either being treated for hypothyroidism or have an underlying dietary cause.

Pets who are affected by hyperthyroidism are also often affected by high blood pressure and other heart-related changes. 

Hyperthyroidism is often easily diagnosed with diagnostic testing such as blood work. 

Prevention and Treatment of Thyroid Problems

While there is no real way that we are aware of to prevent hyperthyroidism in cats, being vigilant about investigating symptoms and bringing your cat in for periodic wellness checks can help us to diagnose and manage this condition early in its course. 

For most pets hyperthyroidism is a very manageable condition, particularly if managed quickly. There are several effective choices for treatment. 

  • Surgical removal of the gland: The thyroid gland can be surgically removed, which stops the production of thyroid hormone entirely. This can result in hypothyroidism or complications due to the removal of the associated parathyroid gland and is not often utilized.
  • Prescription diet: Hyperthyroidism can be controlled by restricting iodine consumption. Iodine is required for the production of thyroid hormone and so feeding an iodine-deplete diet (Hill’s Prescription Diet y/d) can decrease thyroid hormone production if it is strictly fed. 
  • Medication options: The drug methimazole interferes with the production of thyroid hormone, decreasing the effects of hyperthyroidism. It is readily available in pill form, but can be compounded into a liquid or a transdermal lotion for easier administration. Most cats will need to be on methimazole twice daily for life, and sometimes the dose will need to be increased or stop working over time. 
  • Radioactive iodine treatment: I-131 treatment is an often permanent solution for hyperthyroidism in cats. Injection with radioactive iodine strategically inactivates the overactive hormone tissue. For about 98% of patients a single injection is curative. 

Hyperthyroidism in pets can cause some awful symptoms, but when managed appropriately most of our patients do quite well. If you think that your pet might have symptoms of a hormone problem, please contact us as soon as possible. There is no reason for them to have to go any longer without help.