Handling Feline Hyperthyroidism

Lee Stanfield knew that her cat, Origami, seemed to have a more rapid heartbeat than other cats. When she adopted Origami, Lee was told that the affectionate little calico was about two years of age. Despite her slightly unusual heart rate, Origami appeared to be in good health and was loving and playful.

Then a few months ago, says Lee, "Origami started seeming needier than usual and wanting to be held a lot. But she was still eating and drinking and relieving herself normally." Lee thought her cat was just going through a phase. "But one day, Oragami just slept all day," Lee remembers. "I would wake her and she would talk to me, but then she would go right back to sleep."

NOT JUST A PHASE

Lee took her cat to the veterinarian. Tests showed that Origami, who is now four years of age, suffers from hyperthyroidism. This disease is typically caused by a benign thyroid tumor that overproduces thyroid hormone.

Although normal symptoms of hyperthyroidism in cats vary widely, the most common ones are weight loss, hyperactivity, and an extremely strong appetite. "The classic example is an older cat of an average age of 12 or 13," says James Flanders, DVM, DACVS, associate professor of surgery at Cornell University's College of Veterinary Medicine. "These cats suddenly become very active, they might be vocalizing, and they will eat anything they can find. We have had some hyperthyroid cats that go through closets and tear open boxes of pancake mix to eat it. They churn through food and have voluminous stool. Often, their haircoat gets a little messy as well, and they can look like they are almost wild."

Origami was exhibiting signs of a less common form of the disease called apathetic hyperthyroidism, in which the symptoms are different from the normal ones. Cats with apathetic hyperthyroidism are typically depressed, lethargic, and not interested in food.

Regardless of the symptoms, the way the disease is diagnosed is the same.

DETERMINING A DIAGNOSIS

The thyroid glands are flat, floundershaped glands located on both sides of the neck near the throat. When a tumor is present, the affected thyroid glands become enlarged and secrete excess hormones that can affect metabolism.

Veterinarians can sometimes feel the enlarged glands during an examination, and blood tests are done to measure the levels of the thyroid hormones. A diagnostic scan of the thyroid can also be used to diagnose and view the location and size of the affected thyroid.

David Panciera, DVM, MS, DACVIM, a professor at Virginia–Maryland Regional College of Veterinary Medicine at Virginia Tech, recommends routine screening of senior cats. "This should be done annually to evaluate older cats for thyroid disease along with other routine health issues," he says. "Hyperthyroidism is readily treatable."

If you notice any changes in your cat's behavior that last more than a few days, take your cat to your veterinarian. 

Methimazole, an oral drug that interferes with hormone synthesis, is another option. And the good news for cat owners is that there is a more convenient method of administering this medication: The drug can be mixed with a gel that enhances its absorption across the skin. "Rather than having to give pills a couple of times a day, owners can put a little bit of this gel on the inside of the cat's ear, and it is absorbed through the skin," says Dr. Panciera. "The gel is effective in most cases and has given us a nice alternative to the main problem with treating cats—getting a pill inside them."

A third option is surgical removal of the enlarged thyroid gland. In many cases, both thyroid glands are affected, so both glands often need to be removed if this option is chosen. Cats must be monitored in the hospital for a few days after the surgery. Some may need additional supplementation, which may include calcium, vitamin D, or thyroxine.

PAYING ATTENTION PAYS OFF

After considering the treatment options, Lee ultimately chose radioactive iodine for her cat. Testing done 30 days after treatment showed that Origami was producing thyroid hormone at a normal level, an ideal outcome.

Origami is younger than most cats with feline hyperthyroidism. But thanks to Lee's observance of her pet's changes in behavior, as well as early diagnostic testing and treatment, Origami can look forward to a happy future.

TREATMENT OPTIONS
A good treatment option for feline hyperthyroidism is radioactive iodine, which requires a hospital stay of two days to two weeks at a treatment center. "Radioactive iodine is probably the optimal treatment for feline hyperthyroidism because it will completely eliminate the disease in a vast majority of cases," Dr. Panciera says. "The treatment requires a single injection and is simple and safe."

Symptoms of Feline Hyperthyroidism

Talk to your veterinarian if you notice any of these symptoms (or any other changes in your cat's normal behavior):

• Decreased appetite
• Depression
• Hair loss
• Hyperactivity
• Increased vocalization
• Increased water consumption and/or urination
• Lethargy
• Rapid heart rate
• Ravenous appetite
• Rough hair coat
• Vomiting and diarrhea
• Weight loss
   

For more information about Feline Hyperthyroidism, refer to our diseases & conditions library.