Radioactive iodine (I-131) is considered the gold standard treatment for hyperthyroidism in cats. It is very safe and effective, with a cure rate of approximately 97% with one treatment. For the small number of cats that do not return to normal thyroid function following one treatment, a second treatment is typically curative.
VSEC is one of the few centers that have been licensed by the Department of Environmental Protection (DEP) of Pennsylvania to administer I-131 to cats for the treatment of hyperthyroidism. We have been performing the treatment since October of 2011 and typically perform the treatments twice a month.
Prior to treatment with I-131, a baseline diagnostic workup is needed to ensure that the patient does not have any other major medical problems that would preclude treatment with I-131 and also to calculate the dose of I-131 that the patient will receive. All cats must have a CBC, chemistry profile, urinalysis and chest and abdominal radiographs performed within 30 days of the scheduled I-131 treatment. These tests can be performed by your family veterinarian. Please speak with our Radioactive Iodine Coordinator first to determine which of these tests your cat requires and when they should be done. Any ongoing treatment for hyperthyroidism such as methimazole or Hills y/d diet must be stopped 1-2 weeks prior to the I-131 treatment. Additionally, some cats require a recheck thyroid hormone level one week prior to the I-131 treatment to help properly dose the I-131. These details will be discussed with you by our Radioactive Iodine Coordinator prior to the I-131 treatment and she will be able to answer any questions that you might have.
Before your pet is treated, a consultation with Dr. Klag will take place, at which time he will collect a history, examine your cat, discuss the results of previous diagnostic tests and answer any questions that you might have regarding the I-131 treatment. This consultation can take place prior to the scheduled date of I-131 treatment or can take place on the day of treatment, depending on your preference.
Once your cat is admitted to the hospital for the I-131 treatment, he or she will be placed in a special room designed exclusively for this purpose. There are typically several other cats also receiving treatment at the same time in the I-131 room along with your cat, however, there is no direct contact between them. Radioactive iodine is administered as an injection similar to a routine vaccine. It only takes a few moments and is not painful. Our nurse goes to great lengths to make sure the cats are comfortable and well taken care of. The cats must stay in the I-131 room until the level of radiation that they are emitting is at or below the level required by the DEP. This typically occurs in 2-5 days. Our nurse will keep in daily contact with you to give a general update and to let you know when your cat is ready to go home. We request that you bring a few days of your cat’s regular diet so we can maintain as much of their normal routine as possible to keep them comfortable. You may bring a few items to leave with your cat while he or she is staying with us however we are not able to return the items to you so only bring items that you do not want back! Please note that cats treated with I-131 are not permitted to have visitors due to DEP regulations.
Once home, your cat does not need to be isolated but we do recommend you minimize direct contact for a 2 week “safety period”. This period begins on the day they receive the treatment at the hospital. He or she must remain inside, with limited face-to-face contact and cuddling only few times a day for no more than 5 minutes. The cat should not sleep with you during this two week period and they should not be allowed to walk on bathroom and kitchen counters where you would prepare food or place hygienic items. Hands should be washed after contact with your cat and gloves should be used when medicating. You will also need to purchase a separate litter box and scooper to be discarded after this period and use flushable litter. Gloves should always be used when cleaning the litter box, and clumps of feces/urine should be put directly into the toilet and flushed twice. At the end of this period the litter box, any remaining litter, the scooper and any other items that were soiled need to be bagged and stored outside or in the garage for 6 weeks before they can put into your regular garbage pick-up, as required by the DEP.
Please do not hesitate to contact Dr. Klag or his nurse, Diane at 215-750-7884 with any questions about I-131 treatment. We look forward to helping your hyperthyroid cat live a long and healthy life.