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FELINE HYPERTHYROIDISM
Today, hyperthyroidism is one of the most common diseases seen in middle aged
and older cats. With the ease of
diagnosis and availability of medications, it is also becoming more rewarding to
treat and manage the condition.
Very simply, hyperthyroidism is the overproduction of the thyroid hormones, T3
and T4. It is usually caused by an
enlargement of the thyroid gland by a non-cancerous type of tumor.
This causes a high metabolic rate in the
cat that creates most of the symptoms associated with the disease.
The typical hyperthyroid cat is older and often very thin, with a poor hair
coat. Most
owners bring their cats to me because they have noticed an overall
weight loss despite a ravenous appetite.
Other symptoms can include vomiting and diarrhea along with excessive
drinking of water and urinating.
Secondary conditions that often accompany hyperthyroidism include heart disease
and high blood pressure which frequently must be treated in conjunction with the
hyperthyroidism. Concurrent kidney
problems can also occur with the disease and unfortunately can often worsen with
treatment of the hyperthyroidism and must be monitored closely.
Diagnosis is a simple blood test and can be run in most hospitals at a
relatively reasonable cost with results in less than one hour.
It measures the circulating T4 levels in the blood.
This is also the method for monitoring response to treatment after a
diagnosis has been made. Other
diseases can have similar symptoms, so it is also important to check a full
profile on a geriatric cat that is losing weight and an evaluation of the heart
is necessary in most cases. Because
hyperthyroidism is being seen more frequently, many veterinary hospitals are now
recommending routine thyroid testing in cats over seven years old, even if they
are not symptomatic.
Once a diagnosis of hyperthyroidism is reached, there are
three therapy options; 1) antithyroid drugs, 2) surgery, 3) radioactive iodine.
The primary antithyroid medication is methimazole or
Tapazole. It requires
lifetime therapy and can cause side effects, but it is now readily available at
most pharmacies and affordable.
Personally, I have good success with this treatment and have found that most
cats respond favorably with few problems.
It can also be compounded in an ear gel that is absorbed through the skin
and makes medicating much easier.
The T4 level is then monitored every 4 to 6 months for dosage modifications and
success of treatment. Surgery to
remove the thyroid glands is a more radical therapy choice and it can have many
complications due to anesthesia and the procedure itself.
It is also expensive and is generally not recommended.
Radioactive iodine is considered to be the optimum treatment choice, but
it can be cost prohibitive and it usually requires up to ten days of
hospitalization at a specialized hospital or veterinary school.
The treatment, however, is non-invasive and doesn’t require anesthesia.
It is also curative in most instances with no further medications needed.
Depending on the situation, there are advantages and disadvantages of
each treatment. Your veterinarian
can discuss which method would be best for you and your cat.
There are exceptions to the information I have provided.
Rare cases of hyperthyroidism can be caused by a malignant tumor that may
not be responsive to therapy. Other
cases of feline hyperthyroidism may need further diagnostic tests of a free T4
test or a T3 suppression level if the T4 level comes back normal, but
hyperthyroidism is still suspected.
A scan of the thyroid gland can also be performed for a precise diagnosis at
specialized hospitals.
Feline hyperthyroidism is not a death sentence.
In most cases, it can be managed effectively or even cured.
However, it can cause other serious problems and should not be taken
lightly. There is not a right or
wrong way to treat hyperthyroidism.
Every patient and situation is different.
Work with your veterinarian to find the treatment solution that will work
the best for you and help your cat to live a long and happy life. |
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