June 29, 2016 Internal Medicine

New Guidelines for Feline Hyperthyroidism Published

New Guidelines for Feline Hyperthyroidism Published

A cat with hyperthyroidism against a light blue backgroundThe American Association of Feline Practitioners (AAFP) recently issued practice guideline for the diagnosis and management of feline hyperthyroidism. For my last blog post of June, which is the ASPCA’s Adopt a Shelter Cat Month, I thought a brief review of these new guidelines would be of interest to cat families.

Hyperthyroidism is the most common endocrine disease in cats over 10 years of age. Every veterinarian caring for feline patients has more than one patient with hyperthyroidism. The thyroid gland controls metabolism and when it is over active in cats with hyperthyroidism, everything about the cat’s metabolism is turned on. Hyperthyroid cats are more active, burn more calories, eat more food, use the litter box more often, groom excessively and are more vocal than a normal cat.

Grouping Cats with Thyroid Disease

The expert panel authoring the guidelines developed six classifications of cats based on history, physical examination and blood tests. Each group has a different monitoring or therapeutic plan:

  1. Cats with obvious hyperthyroidism and an elevated thyroid hormone level. These cats need immediate treatment.
  2. Cats with clinical signs of hyperthyroidism but without an elevated thyroid hormone level. These cats may need additional testing.
  3. Cats with an enlarged thyroid but normal thyroid hormone levels. These cats need routine monitoring of thyroid hormone levels every six months.
  4. Cats with an elevated thyroid hormone level but without clinical signs of hyperthyroidism. These cats need ongoing monitoring every six months as they may have early hyperthyroidism.
  5. Cats with probable thyroid disease but with another disease, such as chronic kidney disease, that lowers the thyroid hormone level. These cats need more sophisticated blood tests.
  6. Normal cats with no evidence of thyroid disease. Reassess thyroid hormone levels during routine preventive care visits.

Treatment Options for Hyperthyroidism

The expert panel identified four different treatment options available for hyperthyroid cats. The selection of one treatment over another should be made based on each individual cat’s health issues.

  1. Surgical removal of the thyroid gland
  2. Radioactive iodine therapy
  3. Oral or transdermal anti-thyroid medication
  4. Iodine restricted therapeutic diet

Myths about Hyperthyroidism

The expert panel also did some myth busting based on the currently available scientific evidence. At this time, there is no evidence to indicate medications used to treat hyperthyroidism or that the disease itself causes kidney failure. The hyperthyroid state causes an increase in blood flowing through the kidneys.  When hyperthyroidism is successfully treated, the blood flow decreases and kidney values on a blood panel may increase. The hyperthyroid state masks kidney disease.

Radioactive iodine therapy requires quarantine of the treated cat until radioactivity abates. While separation from their family may be stressful to some cats, surgical removal of the thyroid gland, diet change and daily administration of medication for years can also be stressful.
The panel evaluated the various treatments for hyperthyroidism and found them to be similar. The difference is treatments like surgery or radioactive iodine are paid for all at one time, and the cost of medications and therapeutic diets are spread out over time.

Successful Treatment of Hyperthyroidism

Eighty-three to 99% of cats with hyperthyroidism can be successfully treated, but if untreated, hyperthyroidism can be fatal. For more information about hyperthyroidism in cats, the AAFP has created an informative a client brochure.

Tags: amcny, animal medical center, ann hohenhaus, cats, endocrine, hyperthyroid, NYC, pet health, thyroid disease, veterinary, vets,

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