Please feel free to contact us at (517) 353-5420 if you have questions about diagnosis or treatment options for feline hyperthyroidism. A board-certified internist will respond to your call. These guidelines are written for feline hyperthyroidism, the most common cause of which is benign adenomatous change.

Radioiodine may also be useful for treatment of malignant thyroid tumors in both dogs and cats. The MSU Veterinary Medical Center is one of the few facilities in the United States licensed for such treatment. If you have a dog with a thyroid carcinoma or a cat with a malignant thyroid tumor, please contact one of our oncologists at (517) 353-5420 (ask to speak to the internist on consult calls) to discuss treatment options.

Cats that are in relatively stable condition with laboratory-confirmed hyperthyroidism.

Prerequisite Diagnostics: must be performed on all patients before they will be treated. These can be performed at the MSU Veterinary Medical Center or by you, provided they are done within 30 days of admission for treatment.

• Complete thyroid panel, including TT₄ by an accredited veterinary laboratory
• CBC that includes a differential
• Biochemistry panel that includes creatinine, electrolytes, liver parameters
• Urinalysis including sediment exam and refractometer specific gravity (i.e. not the dip stick determination of specific gravity)
• Blood pressure measurement
• Two, preferably three, view thoracic radiographs

Any of these diagnostic tests can be performed at the MSU Veterinary Medical Center if the results are not available with the patient at the time of admission. However, they are not included in the package price.

Patients must be off methimazole treatment for 7 days prior to radioiodine therapy. Patients must also not be eating a prescription iodine restricted diet for at least 14 days prior to treatment.

Cost: The approximate cost is $1,400-$1,600 depending on length of stay required. This includes the cost of an internal medicine office call and consultation, treatment with ¹³¹I, and hospitalization. The cost may vary slightly depending upon the length of hospitalization needed for the patient to reach safe levels of radioactivity. Most patients are able to be discharged 3-5 days after treatment. The cost does not include any of the prerequisite diagnostics.

Appointment schedule: Patients are scheduled and admitted to the MSU Veterinary Medical Center through the Internal Medicine service. Appointments are booked on Mondays or Tuesdays so that patients are more likely to be ready for discharge by the upcoming weekend.

At the initial presentation, the internist will perform a complete physical examination, review all test results, and determine if any additional diagnostics are necessary. Examples might include a recommendation for echocardiogram for a heart murmur, repeat renal evaluation if initial results showed marginal function, or abdominal ultrasound if GI signs are the most prominent. Additional diagnostics are not included in the package price and will be discussed with your client prior to treatment.

Please understand that completion of the prerequisite lab work or additional diagnostics may delay the onset of treatment.

Special considerations or treatment alterations may occur with patients on multiple medications for concurrent conditions. Cats must be fairly stable because radiation safety limits interaction with them to twice daily monitoring. If the patient is deemed too unstable for twice daily evaluation, it may not receive treatment until its condition has been stabilized.

We recommend recheck thyroid profile, renal values and urinalysis at 1 and 3 months, unless the patient’s condition necessitates earlier evaluation. Rechecks may be performed at your clinic or the MSU Veterinary Medical Center through the Internal Medicine service. Please feel free to contact us at (517) 353-5420 (ask to speak to the internist on consult calls), any time you have questions. A board-certified internist will respond to your call.