On April 18, 2000, "Missy" Weidner, a spayed ten year old Domestic Shorthair cat was presented to the hospital for chronic weight loss and occasional vomiting. On physical examination the only abnormalities were a dull hair coat and a rapid heart rate (tachycardia). A tentative diagnosis of hyperthyroidism was made.

Other symptoms of hyperthyroidism are large odiferous stools, temporary blindness due to retinal changes resulting from high blood pressure, and palpable thyroid masses in the ventral cervical (bottom neck) region. A complete blood panel was drawn to confirm the tentative diagnosis. Missy had a very high T4 (thyroid hormone) level.

Figure 1: Scintiscan of Missy Weidner

We immediately put Missy on the drug Tapazole (methimizole) to inhibit the synthesis of thyroid hormone. Unfortunately, she could not tolerate the medicine. This left two options for the Weidners: surgery, which is invasive and risky, or a non-invasive, less risky radioisotope I¹³¹ treatment. The latter was chosen for Missy.

Missy was taken to Dr. Michael R. Broome, DVM, MS, Diplomate American Board of Veterinary Practitioners (ABVP™) who is director of Veterinary Nuclear Imaging in Irvine, CA. A Scintiscan (Figure 1) was done on May 19, 2000 and showed thyroid lobe enlargement.

Missy was treated on June 17, 2000 and remained hospitalized until June 23, 2000. Since her release, Missy has done very well clinically. She is definitely a happy camper. Dr. Broome does warn however, that two recent articles suggest that decreased renal function may occur after therapy for hyperthyroidism in cats. The clinician should be aware of this fact and periodically test the cat's renal blood values.