What to Know About Hyperthyroidism in Cats
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As your cat ages, you begin to notice behavioral changes—she is slower to move in the morning, sleeps more often, eats less often, and may even show signs of dementia or cognitive dysfunction otherwise known as sundowning. One of those changes? Hyperthyroidism.
It is believed that hyperthyroidism occurs in approximately 10 percent of cats, making it the most common endocrine disorder in middle-aged and older felines. Although the condition is believed to develop slowly over time, the good news is that hyperthyroidism—which is classified as an endocrine disorder affecting the thyroid—does present symptoms that cat owners can recognize early on and treat for the betterment of their cat's quality of life.
Veterinarian Lawrence Putter, DVM, owner and chief of staff for Lenox Hill Veterinarians in New York City, explains that despite its prevalence in older cats, hyperthyroidism does not have to adversely affect the lifespan of your pet if treated properly and managed under the care of a veterinarian. In fact, he says that with proper treatment, cats can do quite well and recover from the condition.
"It's somewhat of an insidious disease because it kind of creeps up slowly with symptoms," says Dr. Putter. "There are many cats whose owners do not realize that their pet has it." The condition is considered a multi-systemic disorder due to the over-secretion of the thyroid hormone's effect on the body, but he points out that there are a host of symptoms that can help cat owners and their veterinarians identify the condition and decide on an appropriate treatment plan. Symptoms of feline hyperthyroidism are not limited to, but include: weight loss and muscle wasting, increased appetite, restlessness or hyperactivity, increased thirst or more frequent urination, vomiting, diarrhea, as well as visible and distinct changes in coat appearance.
Diagnosis and Treatment Options
Should your cat present with these symptoms, consult with your veterinarian who can examine your cat and make a diagnosis relatively easily. With proper diagnosis comes proper treatment, including radioactive iodine treatment (also known as I133), which Dr. Putter says "is considered the treatment of choice but is more costly upfront." Another treatment option is oral antithyroid medication (also available as a transdermal treatment, which means it is administered through the skin), but Dr. Putter warns that some cats do not tolerate the treatment very well. An iodine-restricted diet may also be a viable treatment option, with surgical thyroidectomy being the most extreme and invasive of available treatment options. "Thyroidectomy has a number of potential drawbacks which the pet owner would need to discuss with their vet," advises Dr. Putter.
Unfortunately, with hyperthyroidism comes a host of concurrent diseases such as thyrotoxic heart disease, high blood pressure, chronic kidney disease, medically-induced hypothyroidism, and urinary tract infections. Cat owners need to be aware of these side effects, but Dr. Putter points out that overall, "the long-term prognosis is usually very good depending on the treatment chosen, the type of underlying hyperthyroidism (tumor-forming adenoma versus the less common carcinoma) and management of any concurrent diseases." Effective treatment of hyperthyroidism will most likely include daily medication and follow-up visits to the veterinarian, but Fluffy will be grateful for the tender love and care, and ultimately return the good health that you ensure she receives.