Cats must be discharged in a non-cardboard carrier. They cannot be carried or transported loose in the car on the way home.
The small amount of remaining radioactivity in treated cats will gradually disappear over the first 1-3 weeks after being released from radioiodine treatment. Until this is complete, however, these cats will emit very low levels of radiation. Therefore, safety precautions need to be followed during his time frame after release from our nuclear ward. Highlights of those safety precautions that may be relayed to your patient owners are bullet-pointed below:
- Your cat should be discharged from our care in a non-cardboard carrier. If a cardboard carrier is used, and your cat should urinate (or defecate or vomit) in the carrier, necessitating disposing of the carrier, you will need to wait 81 days prior to putting the carrier in the trash until the level of radiation in the urine (or excrement) has reached a low enough level for routine dumping in the trash. (As noted in the bullet point below, garbage dumps have radiation detectors that will detect radiation and you will incur a hefty fine if it is found!). Hard-sided carriers that can be wiped clean are recommended instead of cardboard carriers. (If toilet paper is used to wipe the carrier clean, it can be flushed into the toilet; if paper towels are used, they will need to be stored for 81 days prior to disposal; if a rag is used, it can be rinsed and then laundered as usual – but no bleach).
- Keep your cat indoors (or, if outside, the cat should be under your direct supervision and on a leash in order to minimize the possibility of radiation exposure to other people) for 14 days after release from our hospital
- Do not allow children under the age of 18 or pregnant women to have any contact with your cat, food dishes, toys or litter box(es) for 14 days after release. If you are unable to prevent contact between your cat and children, or you are pregnant and have no way to prevent your cat from sleeping in your bed with you at night, we recommend that your cat be boarded during this 2-week period.
- Limit close up contact time (cuddling, lap time) with your cat to no more than 20-30 minutes per person per day (all at once or spread throughout the day). Avoid sleeping with the cat. You can pet your cat at arm’s length distance as much as you want during this 2-week period as this is a safe distance. (It is not necessary to wear gloves to pet your kitty unless there is a chance that your cat has accidentally soiled its coat with urine or feces). This is recommended in order to minimize your lifetime cumulative exposure. Exposure to other pets is fine.
- Wash hands carefully with soap and water after handling your cat, its food dishes and litter box(es)
- Wear disposable gloves (we will provide to you at release) when handling litter box excrement. Scoop the litter twice daily for 14 days after release. Use a non-scented plastic liner in the litter box for this 2 week period. We recommend use of flushable scoopable litter. All soiled litter must be collected and either flushed down the toilet (ONLY if using flushable litter!) or stored for 81 days after release (if non flushable litter is used). Remember that pregnant women and children under the age of 18 should not have any contact with your cat’s waste products for at least 2 weeks after release from Hypurrthryoid Treatment for Cats. Place gloves and any other items that have been in contact with your cat’s urine or feces in a double lined garbage bag and after the 2-week period, place the bag in a garage, high rise porch or other area of the home away from children and other animals for disposal in 81 days (along with any non scoopable litter).
- To store the litter (if not using flushable litter): Purchase a large bucket (we use 5 gallon paint buckets in our nuclear ward) and line it with a trash liner. Scoop all urine and feces twice daily (from the I 131-treated cat, as well as any other cats that may be using the same litter box as the treated cat). At the end of the two-week period, dump the entire contents of the litter box into the bucket (including the litter box liner), along with any gloves or other items that have been in contact with your cat’s urine or feces during this two-week period. Put the lid on the bucket, assuring that it is well secured, and then store it in a place, preferably out of doors, that is safe from wildlife, etc. (such as the garage or on a high rise porch; if kept inside, it should be kept away from food or high traffic areas and instead stored in a basement storage area, utility room, etc.). Do not dispose of the bucket of litter prior to 81 days (after the 2 week period of collection) since garbage dumps have radiation detectors that will go off if radiation is detected and you will be charged a significant fine!
- There is no risk for other pets. Your cat can share the litter box with other cats in your home, and can play and sleep with other pets as usual.
- If your cat needs to be seen by a veterinarian within the first two weeks after release from our nuclear ward, because Federal and State safety regulations are still in effect during this post-treatment 2-week period, it is important that those regulations be familiar to and followed closely by any veterinary clinic that sees your cat. Basically, no pregnant women or children under the age of 18 can have any contact whatsoever with your cat or its litter box for 2 weeks post treatment, and should not be allowed in the same room as the cat (minimum 6 ft distance from cat at all times). These individuals should also have no contact with the cat’s blood. The same precautions that adults and non-pregnant women need to follow post I 131 during the 1st week at home should be followed by non-pregnant veterinary personnel over the age of 18 examining and treating your cat during the two weeks post I 131. Additionally, any laboratory tests that may need to be run on your cat in the first two weeks post I 131 should not be sent to an outside laboratory, and should instead be run in-house since there are still low levels of radiation in blood, urine and stool (fecal material) that personnel in the large veterinary laboratories should not be handling. In-house laboratory equipment with the exception of those that use rotors, etc., will require flushing after being used to test blood from a post I 131 patient during the first two weeks post treatment. We are happy to see your cat at VCA Cat Hospital during this time frame period if your family veterinarian prefers.
- Some clients will ask if their cat can be boarded after I 131 treatment if safety precautions may be difficult to implement in the home setting. If you know you cannot easily follow the recommended safety precautions (you are pregnant or cannot avoid prolonged close contact with your kitty, flush the litter, etc.), then boarding your cat may be necessary. We can certainly board your cat during this time frame.
Alternatively, if your veterinarian is able to board your cat and have his/her staff follow the same radiation safety guidelines that you would be following at home, including properly handling the cat litter and avoiding close, prolonged contact with your cat, then that is an acceptable option as well. We are happy to review these safety precautions with your veterinarian.
Patients should have blood work rechecked (at your facility) one month after radioiodine therapy (and then again at 3 and 6 months). At minimum, a T4, cTSH, BUN, and Creatinine from any major veterinary laboratory be submitted. Please forward the laboratory results to us. Now that we are using more conservative dosages of radioiodine to treat our hyperthyroid patients, we are trying to closely track post I 131 test results to assure that these dosages are adequate to treat the hyperthyroid condition without resulting hypothyroidism.
There are few adverse effects or risks with radioiodine therapy. Since the iodine is specific in its site of action, there is no hair loss or increase in skin pigmentation, as may be seen with other forms of radiation therapy (cobalt radiation). Some cats seem to experience mild discomfort of the thyroid region (thyroiditis at the beginning of therapy but this resolves itself spontaneously and does not cause a problem. A permanent voice change, although rare, is possible.
Occasionally, a cat will develop hypothyroidism after treatment with radioiodine. This occurs less commonly now that more conservative dosages of radioiodine are being used by many radioiodine facilities. Hypothyroidism may be self-limiting, and may or may not require treatment (depending on the cat’s clinical signs, kidney status, etc.). In those cases that require treatment, the condition usually resolves with levothyroxine supplementation. More often than not, the supplementation is not needed permanently, but may be needed in others.
Cats with or without known underlying kidney disease may develop more obvious signs of the kidney disease once the ‘masking’ effects of the hyperthyroidism are removed. Overall, side effects are extremely rare.