Treatment is geared towards lowering the thyroid hormones back into a normal range. This can be accomplished three ways:
1. Putting the animal on Tapazole® (methimazole), on an initial loading dose and maintenance dose, will lower the thyroid hormones back to a normal range in a few weeks. The drug prevents the formation of thyroid hormones. The disadvantage to this: cats hate to be pilled. Independent compounding labs are able to manufacture a paste that is applied daily to the ear flaps. Use gloves when applying this to the animal's ears. This replaces oral therapy. It is a daily life long commitment and if therapy stops abruptly the thyroid hormones will resume their climb back to excessive levels. Problem is, is that long term use of the drug does not stop the thyroid adenomas from growing. T4 and FT4 levels have to be checked frequently until the cat is stabilized and than twice a year.
2. Surgical removal of the thyroid glands. This is straight forward but the big problem is that the parathyroid gland is diffuse and can not be differentiated visually from the thyroid gland in the cat. There may be future serum calcium issues.
3. Radioactive Iodine. This is a costly procedure but it is a one time treatment in the cat. Methimazole is not cheap so the cost over the life time of the cat is more reasonable. It requires no anesthesia and the drug is administered subcutaneously. This procedure is only performed in facilities that have a special license. Animals are all hospitalized. Great thing is, is that thyroid hormone levels reach normal limits in a week or two.
Cats that have developed secondary cardiomyopathy will need to be treated for that disease.