Cats and people have a gland called the Thyroid gland which regulates
the bodies metabolism. The gland consists of two parts one located on each side of
the neck. Sometimes thyroid tissue can also be located near the chest and this is
called ectopic thyroid tissue. Feline Hyperthyroidism is a disease of the thyroid
gland resulting in the excessive production of thyroid hormone (hence the term
"Hyper" thyroidism). It is the result of a tumor growing on the thyroid
gland and in 98% of the cases the tumor is benign. The excessive production of
thyroid hormone speeds up the metabolism and causes a number of problems. Some of
the more common signs include behavior changes, weight loss, excessive eating, excessive
drinking and urination, rapid heartbeat, shedding of fur and vomiting. Prolonged
Hyperthyroidism can cause kidney problems, heart murmurs as well as irregular heart
beats. Gone untreated, the condition can result in kidney failure and heart damage
and eventual death. It most commonly occurs in older cats (cats greater than 8 years
old).
If your cat has been diagnosed with Feline Hyperthyroidism, there are three treatment
options available and these are (1) medical therapy,
(2) surgical removal of the thyroid gland and (3) radiation therapy.
Medical Therapy
Medical therapy is the treatment of the disease using drugs. The most common
medication prescribed is Tapazole and it comes as a pill or it can be formulated into a
liquid. The medication does not cure the condition (your cat will still have a
thyroid tumor) but it, in effect, decreases the amount of thyroid hormone in the blood
stream. The medication is given once or twice daily for the rest of the cat's life
and it can have some side effects. Cats are not the easiest animals to
medicate. To ensure that your cat gets the proper dosage, you physically have to
give the cat the medication. After doing this once or twice a day, everyday, the cat
typically begins to rebel and medication time becomes a major chore. Side affects
such as anorexia, blood and liver problems, vomiting and lethargy can occur. Because
some of these side effects can become serious, periodic blood work is required to monitor
the cat's condition. The cost for the medications can range from $25.00-$50.00 a
month ($300-$600 a year), depending on the dose level, for the rest of your cats
life. The periodic blood tests will also add to the yearly costs.
Surgery
The second option is the surgical removal of one or both thyroid glands. When a
cat becomes hyperthyroid, the gland producing the excess hormone frequently becomes
enlarged and can be surgically removed. In some cases, the remaining thyroid gland
and/or ectopic thyroid tissue may also have hyperthyroid components but the tissue is not
enlarged. In this case, removal of the enlarged thyroid gland will not be curative
and the hyperthyroid condition may reoccur. Also many hyperthyroid cats have heart
problems which increases the anesthetic risk during surgery. Finally, there is the
chance for the removal of the parathyroid gland which is located immediately next to the
thyroid gland. This would result in low calcium levels in the blood, a potentially
life threatening condition. The cost for the surgery can range from $600-$1,000
(without any surgical complications) and there is a good chance that the surgery may have
to be repeated. Blood work will also need to be performed to ensure that the thyroid
hormone levels are back to normal and that no other problems arise.
Radioiodine
The third option is the treatment of the hyperthyroid condition using radioactive
iodine. The treatment consists of injecting a single dose of radioactive
iodine into the cat. When absorbed in the body, iodine is concentrated in the
thyroid gland and those cells which are most active (i.e. thyroid tumor cells) will absorb
most of the radioiodine. Therefore, the radioactive iodine preferentially enters the
tumor cells in the thyroid gland and the radioactivity kills these cells while doing very
little damage to the normal thyroid cells. Through normal bodily processes, the
radioactive iodine is removed from the body and is lost primarily in the urine and to a
lesser extent in the feces. There is no anesthesia and the success rate is
approximately 95%. The cost for the procedure ranges from $800-$1,100. The
cost for the blood work, which has to be performed before and after the treatment would be
an additional cost. The main drawback is that the cat will have to stay at the
treating hospital until the levels of radioactivity have dropped to below the levels set
by the State and the Federal Government. This may take as little as five days or as
much as a week.
KINDNESS
ANIMAL HOSPITAL