Treatment of feline hyperthyroidism using orally administered radioiodine: a study of 40 consecutive cases

SUMMARY Forty cats with hyperthyroidism were treated using 200 to 300 (typically 250) mBq of orally administered ¹³¹I. Thirty-six cases (90%) were successfully treated, as assessed by resolution of clinical signs and reduction In plasma thyroxine concentrations to normal or reduced values after treatment. Although higher doses of ¹³¹I appear to be required when the radioisotope is administered orally rather than Intravenously, a less stressful administration procedure and greater availability of therapy capsules offer useful advantages for treating thyrotoxic cats.