Cat hyperthyroidism is a common disease and is caused by the excess of thyroid hormones, produced by the thyroid glands in the cat's body. The increased production of thyroid hormones may be caused by a number of underlying conditions affecting the thyroid or the pituitary glands.
Cat hyperthyroidism is the most common endocrine disorder that affects felines. The condition occurs as a result of the production in excess of thyroid hormones secreted by the thyroid glands. The thyroid gland is made up of two lobes and can be found on each side of the trachea, in the neck. The thyroid gland is responsible for:
- The production of the major thyroid hormone called thyroxine (T4)
- The production of triiodothyronine (T3)
These hormones are vital because they regulate the body's metabolic rate. The pituitary gland, a part of cat's the brain, produces a hormone, the thyroid stimulating hormone (TSH), which controls the production of the thyroid hormones as well.
Causes of Cat Hyperthyroidism
The causes of cat hyperthyroidism may include:
- A high amount of benign cells in the thyroid gland, which is the most common cause of hyperthyroidism in cats. These cells may cluster in small nodules on the thyroid gland; these nodules are known as adenomas. Adenomas may affect one or both lobes of the thyroid gland.
- Malignant cells, which develop in the same way as the benign cells on the thyroid gland lobes. However, this accounts for less than 2 percent of hyperthyroidism in felines.
- Benign or malignant growths in the pituitary gland area.
- The diet of the cat, which may affect the thyroid or the pituitary gland.
- Immune system diseases.
- Changes in the pet's environmental conditions.
The vet will perform a few tests and an examination of the cat. The palpitation of the thyroid gland can't give a precise diagnosis because other diseases such as feline diabetes or renal failure may also cause an abnormal growth of the thyroid glands. Blood tests will show the levels of the T3 and T4 hormones. A T3 suppression test may also be performed. Thyroid imaging may also be used to diagnose hyperthyroidism.
Treatment Options for Felines
Hyperthyroidism in felines can be treated using three different methods, each treatment having both advantages and disadvantages:
- Medication therapy (i.e. Methimazole), which will manage the symptoms of hyperthyroidism, but will not cure the underlying disease. This type of treatment may have side effects such as vomiting, lethargy and anorexia.
- Surgery or thyroidectomy, which involves the removal of the affected thyroid glands and may also remove the possible cells grown on the lobes of the thyroid glands. The surgery is a permanent cure; however, there are numebrous risks associated with anesthesia and the surgery.
- The radioactive iodine treatment will involve an injection which will reduce the hyperactive thyroid tissues and is a permanent solution.