131-I Therapy

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Radioactive iodine (131I) therapy is an accepted treatment for cats with hyperthyroidism. Numerous publications advocate the use of 131I therapyfor cats with thyroid adenoma or carcinoma. 131I therapy is noninvasive (compared to surgery) and usually only 1 dose is enough to return the animal to a normal, euthyroid state (compared to daily administration of conventional anti-thyroidal medication.) Cats typically return to a normal, euthryoid state 2 and 4 months after 131I treatment.

Scheduling systemic 131 Iodine therapy and pretreatment evaluation

Due to limited available space and personnel, and to limit human exposure, the number of animals scheduled for 131I therapy at the OSU Veterinary Medical Center is limited. For appointments, call the OSU Veterinary Medical Center: (614) 292-3551.

At the OSU Veterinary Medical Center, the minimum pre-treatment evaluation for each cat consists of:

  • CBC, Chemical profile, Urinalysis, Blood Pressue
  • Plasma T4 concentration

Further evaluation is available, if necessary, consisting of:

  • 99m Tc-pertechnate scintigraphy (thyroid scan)
  • Nuclear medicine renal function studies: GFR and ERPF (if needed)

Patient's care during treatment

After 131I administration, the cat is transported to an isolation ward to comply with State of Ohio, radiation safety regulations. During isolation, the owner is may not visit the cat. A fourth –year veterinary student and radiology personnel will care for the cat. Each cat’s radiation level is monitored daily. Cats are released to their owners when their radiation exposure level is below 50 mR/hr at the skin surface over the thyroid glands (usually 4 – 7 days after 131I administration).

Learn about patient care after release