RESPONSE TO HIGH-DOSE RADIOACTIVE IODINE ADMINISTRATION IN CATS WITH THYROID-CARCINOMA THAT HAD PREVIOUSLY UNDERGONE SURGERY

Seven cats with thyroid carcinomas that had previously undergone surgi cal removal of neoplastic tissue were treated with 30 mCi of radioacti ve iodine (I-131). Six of the cats had clinical signs of hyperthyroidi sm; 1 did not. There were no complications associated with I-131 treat ment, and clinical signs resolved in all cats. Technetium scans of 4 c ats made after treatment did not have evidence of isotope uptake. In t he remaining 3 cats, small areas of isotope uptake, the intensity of w hich was equal to or less than the intensity of uptake in the salivary glands, were seen. All 7 cats became hypothyroid after treatment, 4 r equired L-thyroxine supplementation. One cat was alive 33 months after treatment. The other 6 cats were euthanized because of unrelated dise ases 10 to 41 months after treatment.