LAUSR

ABSTRACT The uptake of radioiodine in veterinarians or veterinary staff when 131I is administered via injection to domesticated cats (Felis catus) with hyperthyroidism has not been well studied. Veterinarians and staff undergo specific training for the handling of radioiodine injection of cats to minimize and prevent an inhalation intake. An in-vivo bioassay is performed post cat injection to determine if 131I was inhaled or absorbed. The frequency of in-vivo bioassays requires dedicated time of the veterinarians and those who must perform the bioassay. Bioassay data from veterinarians and staff at the Colorado State University Veterinary Teaching Hospital administering 131I from the past 20 years were analyzed (n = 168) to ascertain if there is a correlation between the amount of time elapsed between the 131I administration, the bioassay, and the net counts resulting from the bioassay. The amount of 131I administration and the bioassay net counts were also analyzed to determine if there was a correlation. No correlations were found, and out of 168 131I administrations over 20 years, only 3 bioassays resulted in measurable doses of 131I with a committed dose equivalent (CDE) of 0.19 mSv, 0.77 mSv, and 1.6 mSv. The current precautions taken to prevent the inhalation intake of 131I appear sufficient to consider changing the requirements for veterinary bioassay after routine administration of 131I to cats.