What is the thyroid gland? 

The thyroid gland is found near the trachea (windpipe), just below the larynx (voice box). It is a paired gland that is responsible for the production of thyroid hormones. The major thyroid hormone that is produced by the thyroid gland is thyroxine (T4). A small amount of another thyroid hormone, triiodothyronine (T3), is also made by the thyroid gland. Thyroid hormones have far-reaching effects on the body, in essence governing the body’s metabolic rate.  The function of the thyroid gland is controlled by the pituitary gland at the base of the brain, through a hormone called TSH (thyroid stimulating hormone). 

What is Hyperthyroidism?
Hyperthyroidism, also known as "hyperthyroid disease," occurs when the thyroid gland enlarges, and starts producing excess amounts of thyroid hormone (thyrotoxicosis). This anomaly is usually caused by a benign tumor on one or both of the thyroid gland's lobes. Although thyroid tumors can be cancerous, the chances are only 2% to 5% of malignancy.

What are the Symptoms?
Not all symptoms will be seen in every cat with hyperthyroidism, but any one or two of them should be a strong indication that a veterinary examination is indicated. Some or all of the following symptoms may be present in a hyperthyroid cat:

*Increased Appetite
*Unexplained Weight Loss and loss of muscle mass
*Irritability or Nervousness
*Frequent Vomiting
*Unkempt-looking Coat
*Diarrhea
*Excessive Thirst (polydipsia)
*Weakness
*Lethargy

How is Hyperthyroidism Diagnosed?
Physical Exam: The veterinarian will palpate the cat's neck area, and may feel the enlarged gland(s). Heart rate and blood pressure will also be checked.
CBC: Since hyperthyroidism can mimic the symptoms of other diseases, such as CRF or liver disease, a blood panel will usually show the "big picture," when combined with a thyroid-specific test, usually the T4, which will show thyroid levels. Elevated levels of T4 will usually strongly indicate the presence of hyperthyroidism.
However, some older cats may fall within the "normal" range, and still have the disease. When in doubt, other thyroid screening tests can be give.
As hyperthyroid disease can predispose to other conditions, such as hypertrophic cardiomyopathy or hypertension, the blood panel will also reveal pertinent information on the heart and other organs, which is essential to know prior to choosing an ultimate treatment.

How is Hyperthyroidism Treated?
Three basic treatments each offer a strong possibility of controlling thyroid hormone levels. They include medication, surgical removal of the glands, or radioactive iodine. Each patient and case is different and the BEST treatment will be determined by the veterinarian according to your pet's needs. 

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