The Fast and the Purr-ious
The Fast and the Purr-ious
Do you ever wonder why some people can eat an entire birthday cake and never gain a pound and another person can lick the icing and burst a belt loop? Ever wonder why some people are bouncing off the walls with energy while for others every step is a struggle to stay awake? Many factors determine an individual’s metabolic rate, but one of the larger components is the function of the thyroid gland.
The thyroid gland, a two-lobed organ that sits on the front side of the trachea, produces a hormone that helps regulate metabolic rate, blood pressure, heart rate and a host of other essential body functions. In the vast majority of young, healthy animals the thyroid gland works well. However, as our feline friends age, the thyroid gland can kick into overdrive and a once sedentary, plump, content kitty can change in an instant.
Older cats are predisposed to benign adenomatous hyperplasia, a condition that results in non-cancerous overgrowth of the thyroid gland. More tissue means more thyroid hormone production, resulting in a speedy metabolism. Owners usually notice rapid weight loss due to the increased need for energy from a ramped up metabolic rate. They may also see a voracious appetite, behavioral changes like increased energy and aggression, vomiting, diarrhea and increased drinking and urination.
The test to determine thyroid disease is simple. The veterinarian sends a blood sample out to a lab to test levels of thyroid hormone (T4) and free-thyroid hormone (fT4). If these values are increased, the cat is confirmed to be hyperthyroid. At the same time we also check kidney values, liver values, red blood cell levels and a urine sample. Hyperthyroidism has a wide array of affects on the body due to the vast number of functions of thyroid hormone. Almost every organ can be affected by increased thyroid levels in the blood.
Treatment of hyperthyroidism is also generally simple. Patients can be started on a drug called methimazole that selectively destroys thyroid tissue, thereby reducing the amount of thyroid hormone produced. Regular monitoring is needed after starting methimazole to make sure the patient is not being under-treated or over-treated (since low thyroid hormone causes its own set of problems). Methimazole is a life-long medication but is very affordable and generally easy to administer. AMC works with pharmacies that can compound this medication into chewable treats, liquids, and gels that are absorbed through the skin at an increased cost.
Alternatively, cats can be treated by I-131 radiation therapy to completely cure the disease within a few days. The patient is injected with a radioactive form of iodine which is quickly absorbed by the thyroid gland. The radiation destroys the overgrowing tissue and returns the thyroid to a normal state. This procedure is only offered at specialty clinics and is generally reserved for cats that are otherwise completely healthy. Cost may be a prohibiting factor, but for the some the convenience of not giving pills is worth the bills.
After either treatment, the veterinarian will want to recheck thyroid and kidney values to make sure they are normal. This is because hyperthyroidism can mask chronic kidney disease. After treatment, kidney values may rise, reflecting underlying kidney disease that was previously not detectable.
Hyperthyroidism is a very common and very treatable disease of older cats. Left untreated it leads to hypertension, heart failure, chronic kidney disease, muscle wasting and dangerous weight loss. Talk to your vet or the staff at AMC if your cat exhibits any of the early symptoms. We recommend annual blood testing to detect early thyroid disease before your cat is bouncing off the walls.