Treatment of Feline Hyperthyroidism – Medical Management

Medical treatment is used for long term disease management as well as prior to surgical thyroidectomy or radioiodine therapy.

The mercaptoimidazoles, thiamazole (methimazole) or its prodrug carbimazole, are used. Thiamazole interferes with the synthesis and production of thyroid hormones by inhibiting thyroid peroxidase-catalyzed reactions.

Hematology, biochemistry and TT4 should be monitored frequently especially during the initial stages of treatment.

Side effects of medical treatment

Side effects are quite common especially during initial treatment but are usually mild and transient:

  • Anorexia
  • Vomiting
  • Lethargy

Less frequently hepatopathies, cutaneous reactions, blood dyscrasias and bleeding tendencies may be seen. In these cases treatment should be suspended.