Hyperthyroidism is the most common hormonal disorder diagnosed in cats. It occurs when the thyroid glands, located in your cat's neck, produce an excess of thyroid hormone.

Thyroid hormone helps regulate and control normal bodily processes. It controls how fast or slow the body functions. When a cat's thyroid gland becomes overactive and produces too much hormone, an increase in the body's metabolism occurs. Over a long period, the overproduction of thyroid hormone will have a negative impact on the heart, kidneys and other organs.

The exact cause of hyperthyroidism is not known. This disease typically affects cats ages 7 years or older, both male and female. The most common symptoms are weight loss, despite a desire to eat more than normal, and restlessness. Additionally, some cats may look unkempt, vomit, drink more, urinate more, become cranky and breathe more rapidly. In some cases, you can even feel the thyroid glands on your cat's neck because they sometimes become enlarged.

So what do you do if you suspect your cat is hyperthyroid? Contact your veterinarian. He or she can run some simple tests to determine if your cat has this disorder. These may include:

· Chemistry tests to evaluate kidney, liver and pancreatic function, as well as sugar levels

· A complete blood count to rule out blood-related conditions

· Electrolyte tests to ensure your cat is neither dehydrated nor suffering from an electrolyte imbalance

· A thyroid test, which determines if the thyroid gland is producing too much thyroid hormone

· A urinalysis to rule out urinary tract infection and to evaluate the ability of the kidneys to concentrate urine

Treatment of hyperthyroidism

If your cat is diagnosed with hyperthyroidism, your veterinarian will discuss treatment options.

The three most commonly recommended treatments are:

Oral or topical medication: The generic name for this medication is methimazole, and it will help reduce the production of your cat's thyroid hormone, essentially helping your cat's metabolism return to normal. This medication doesn't reduce the size of your cat's thyroid glands; it disrupts the production of the hormone itself. This medication will have to be given for the rest of your pet's life and is often administered twice a day. If you and your veterinarian decide that medication is the right option for your pet, follow-up tests are recommended to ensure that your cat is on the correct amount of medication and there are no adverse effects.

Radioactive iodine therapy: This is considered a safe and effective treatment for cats, offering a permanent cure. The treatment can be expensive because your pet will require special care while being treated, but once the treatment is done, your cat will not require medication or further treatment. Your veterinarian will discuss with you whether or not your cat is a good candidate for this treatment.

Surgery: Your veterinarian may recommend the removal of the growth(s) on the thyroid gland. He/she will discuss with you whether or not your pet is a good candidate for this treatment.

My personal opinion in light of treatment is as follows. Surgery would be the last option, as it is the most aggressive and expensive. If you have a cat, say less than 7 years old, I would suggest iodine treatment as you may not want to daily medicate your cat for years. If your cat is older, as the majority of diagnosed cats are, then daily medication via pills, an oral flavored liquid or even transdermal application would be the best option.

The importance of annual senior blood work (more than 7 years old) is recommended to diagnose hyperthyroidism, many times before symptoms are seen. Tests also help rule out kidney disease and diabetes, which show similar symptoms.

Preventing the disease

If your cat was diagnosed with hyperthyroidism, there is no one to blame! Remember, even experts are unsure why some cats become hyperthyroid. Diagnosing and treating your cat effectively will allow your dear friend to live a long and healthy life!

Dr. Darren Woodson has practiced veterinary medicine in the Farmington area for more than 28 years and has a passion for educating pet owners. If you have a question you would like him to address, email dwoodson@valleyvetpet.com. Please understand Dr. Woodson will choose the questions that are most relevant to our readers.