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Cat Health Care
Information by Condition or Disease

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Any health care links located here are NOT to replace a veterinarian visit; please take your cat to a vet immediately at any sign of odd behavior or any symptoms of illness or injury. Call your vet and describe your cat's symptoms with any of your concerns about the cat's well-being. Your veterinarian may discover changes in your cat's health that you have overlooked. It is always better to err on the side of caution.

Hyperthyroidism

With advancements in nutrition and medical care, cats are living to older ages than ever before. With the older age comes diseases which we were unfamiliar with before because most cats did not live long enough for them to develop. One such disease is hyperthyroidism.

The disease is an overactivity of one or both of the thyroid glands in the neck, which is very common in older cats. Because these glands control the metabolic rate, affected cats will tend to be overactive, eat and drink more than usual, yet lose weight dramatically. If the condition is left untreated, the racing heart becomes unable to cope with the strain, and the cat will die from heart failure. Treatments include drugs, surgical removal of one or both glands, or radioactive iodine.

The thyroid gland consists of two flat lobes located on each side of your cat's windpipe. These lobes are flattened and cannot routinely be palpated. Embedded in the front end of each thyroid gland are the parathyroid glands. The thyroid gland acts as the thermostat for the metabolic rate of the body, controlling the speed of (how fast or slow) the body functions. It produces two hormones, referred to as T3 and T4 which circulate throughout the body and affect sensors on the organs of the body.

Hypothyroidism is a condition where there is not enough thyroid hormone produced by the body and thus the metabolic rate slows down. Animals that are hypothyroid usually become obese (weight gain), become less active (lethargic), are more cold sensitive (cold intolerance), and have multiple skin problems that can vary from itching to flaking to hair loss. Cats are rarely affected by hypothyroidism.

Hyperthyroidism results when the thyroid gland produces an excess of thyroid hormones. This happens most commonly when the thyroid gland has become cancerous. Hyperthyroidism most commonly develops in cats over eight years old. Cats that are hyperthyroid are usually hearty eaters, sometimes even ravenous, yet they continue to lose weight in spite of how much they eat. A more serious consequence of hyperthyroidism is the development of a hypertrophic (increased muscle wall) cardiomyopathy (disease of the heart). This is first detected by an increased heart rate and confirmed by x-rays and ultrasound. Other signs can include increase thirst, increased urination, vomiting, diarrhea, behavioral changes and central flexion of the neck. Not all cats exhibit all of the signs listed above; however, hyperthyroidism must be considered in any cat over eight years of age that is acting ill or losing weight. It is diagnosed by a blood test that measures the thyroid hormone.

Because other diseases can show similar signs like diabetes and renal (kidney) insufficiency, it is important to evaluate all of the organs of the body at the same time.

Once hyperthyroidism has been diagnosed treatment can be very successful. There are three methods to treat hyperthyroidism, medical treatment, surgical treatment and irradiated iodine treatment. The following table lists these ways and their advantages and disadvantages:

TREATMENT	ADVANTAGES	DISADVANTAGES
Medical - daily tablet	Non-invasive Lower cost Does not require anesthesia	No restriction of growth of tumor Side effects include vomiting Need to give your cat a pill daily
Surgical - remove thyroid	Immediate response to treatment No vomiting as side effect Can be done by most veterinarians	Requires anesthesia Risk of removing parathyroid glands There may be thyroid tissue in other parts of the body not removed, thus no cure
Irradiated Iodine - inject radioactive iodine into vein which destroys thyroid tissue	Non-invasive given by injection No anesthesia involved Gets to all thyroid tissue in the body	Most costly of treatments Requires three days hospitalization

All three of these treatments can be successful. Which one is best for your cat depends on a combination of factors including the cats age, other concurrent conditions, your veterinarian's surgical expertise, and your financial resources. Medically, irradiated iodine is the treatment of choice.

As our cats live to older ages, diseases which we have never seen before are being detected. Reasons for this include the fact that we are now more aware of these conditions and are looking for them, our methods of detection are better and cat owners are more willing to pursue diagnosis and treatment. The best way to assure your cat is diagnosed for hyperthyroidism or any other disease is to have timely physical examinations. Your cat should receive thorough physical examinations annually between the ages of 1 to 9 and twice a year from 10 years and older. Patients with existing conditions may need to be checked even more frequently.

Diabetes, kidney disease, liver disease and other conditions that also affect older cats need to be ruled out prior to settling on a diagnosis of hyperthyroidism, even if tests indicate it is present. In older cats, this disease is common enough that routine screening is considered to be necessary by many veterinarians. Due to the potential for numerous secondary complications, such as heart disease and digestive problems, early diagnosis is a good idea. Consider asking your vet about tests for hyperthyroidism if your cat is 8 - 10 years of age.

Additional information can be found at Hyperthyroidism in Cats.

Resource References:
Cat Doctor, Dr. Mark Evans
Cat Owner's Question and Answer Book, Bradley Viner
Page URL: http://www.sniksnak.com/cathealth/hyperthyroidism.html

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