Hyperthyroidism in Cats.

Hyperthyroidism in Cats:Hyperthyroidism is a very common disease afflicting primarily middle-aged and older cats, also called thyrotoxicosis. Hyperthyroidism is caused by an increase in production of thyroid hormones (known as T3 and T4) from enlarged thyroid glands in the cat's neck. In most cases, enlargement of thyroid glands is caused by a tumor called an adenoma, which is non-cancerous but some rare cases of hyperthyroid disease are caused by malignant tumors known as thyroid adenocarcinomas. Thyroid hormones affect nearly all the organs in the body; therefore, thyroid disease can sometimes cause secondary problems. Thyroid hormones stimulate a faster heart rate and a stronger contraction of the heart muscle. Over time, cats with hyperthyroidism may develop an enlargement and thickening of the left ventricle of the heart. If left untreated and unmanaged, these changes will eventually compromise the normal function of the heart and can even result in heart failure. This means that in some cats with hyperthyroidism, additional treatment may be required to control secondary heart disease. However, once the underlying hyperthyroidism has been controlled, the cardiac changes will often improve or may even resolve completely. Signs usually observed in cats afflicted with hyperthyroidism which may be subtle at first but then become more severe as the disease progresses. The most common clinical signs of hyperthyroidism are weight loss, increased appetite, and increased thirst and urination. Hyperthyroidism may also cause vomiting, diarrhea, and hyperactivity. The coat may appear matted or greasy. more