I-131

Frequently Asked Questions

Your cat’s follow-up exam should take place about 4 to 6 weeks after treatment. During this time, blood work will be performed to evaluate the thyroid level and renal values. You should see the symptoms of hyperthyroidism start to diminish before your recheck appointment.
For your protection, owner visitation is not allowed. Your cat will be hospitalized in a protected area of the hospital, specifically designed for I-I31 feline patients. We assure you that your pet will have multiple staff visits throughout the day by our certified I-131 technicians and veterinarians and will be given plenty of attention. You may also bring a disposable, small toy for your cat to play with during their hospitalization. Due to potential contamination, the toy will be properly disposed of by our hospital staff at the end of your cat’s stay with us.
Cats receiving I-131 are hospitalized in a protected area so their radioactive levels can be closely monitored. Since they are receiving a radioactive treatment, cats are unable to receive any elective procedures during their hospital stay.
The dose of I-131 used for feline hyperthyroidism is very small. People and other animals in the household are at a very low risk from radiation. Cats will not be discharged until they reach an acceptable low level of radioactivity. However, there will be a low level of radioactivity for approximately 80 days post treatment. We will give you a list of guidelines upon your cat’s discharge from the hospital to help minimize your family’s exposure. These guidelines include not sleeping with your cat, washing your hands after touching your pet, and wearing plastic gloves when changing the litter. Since radioactive iodine is excreted in the cat’s urine, waste from your cat’s litter box should be bagged separately from the normal household trash for approximately two weeks after your pet’s discharge from the hospital. After this time period, the litter can be disposed of with the regular household trash if you choose. Pregnant women and children under the age of 18 should not be in contact with the family cat during this period.
Screening for other non thyroid-related diseases (i.e., renal and heart disease) is important prior to beginning I-131 therapy. Blood work, including a complete blood count, chemistry, and thyroid levels, should be performed within a month of treatment. Radiographs (X-rays) of the chest should also be done to evaluate the heart and lungs. Cardiac evaluation with an echocardiogram is also recommended. If all screening tests are normal, then your cat is a suitable candidate for I-131 therapy. In preparation for treatment, your cat will need to stop taking tapazole for 10–14 days beforehand.

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