LONG-TERM FOLLOW-UP OF HYPERTHYROID CATS TREATED WITH I-131

A long-term follow-up study of hyperthyroid cats treated with iodine-1 31 was conducted at the Texas A&M University Veterinary Teaching Hospi tal. Between January 1985 and December 1990, 255 cats were treated. Ba sic demographic data, information on treatment, and diseases at the ti me of diagnosis were recorded. Two hundred and thirty seven cats had l ong-term follow-up data collected by telephone interviews with the ref erring veterinarian and/or the owner on outcome of therapy, diseases t hat developed during the follow-up period and survival. Risk for devel oping hyperthyroidism was highest for cats greater than 10 years of ag e. There was no breed predisposition. Neutered cats were slightly over -represented among the cases compared to intact animals. Eighty-five p ercent of treated cats became clinically normal and remained euthyroid for a median time of 17.5 months. Four percent remained hyperthyroid and 9% became hypothyroid, requiring thyroid hormone supplementation.