Hyperthyroidism (HyperT)

Hyperthyroidism (overactive thyroid) is the most common thyroid disease to affect cats. Cats suffering from hyperthyroidism produce too much of the thyroid hormones, this increases their metabolism and leads to:

  • weight loss
  • increased appetite
  • increased activity and restlessness
  • a matted, greasy or poor hair coat
  • a fast heart rate
  • increased water drinking
  • vomiting
  • diarrhea
  • occasionally difficulty breathing
  • weakness

Hyperthyroidism can be controlled with a low-cost daily medication, or with radioactive iodine to destroy some of the thyroid gland so that thyroid function normalizes. If hyperthyroidism is left untreated it is fatal.

Disease Information Sites

Tanya’s Comprehensive Guide to Chronic Kidney Disease covers hyperthyroidism as well as some other thyroid diseases that affect cats. This site is particularly helpful if your cat also suffers from Chronic Kidney Disease.

Thyro-Cat has some pretty good information about hyperthyroidism and how to treat it.

Support Groups

Feline Thyroid Management is an email-based support group that is very active. Their members are very experienced with managing hyperthyroidism in relation to kidney disease, and in managing cats who have had radioactive iodine therapy.