BVSC I-131 Protocol

We do not require medical pre-treatment prior to I-131 therapy but do insist on a known serum creatinine within one month of the anticipated treatment date. It is ideal to have a total T4 off treatment within a month of the I-131 also. However, if the original diagnosis is fairly recent then total T4 at diagnosis will usually suffice.

If total T4 is greater than the lab’s measurable upper limit, then it is helpful if a dilution is requested – Idexx will do this at no charge. If a cat is currently on medical treatment then we ask that this is discontinued at least 14 days prior to the treatment date. If a cat has been on Hills y/d diet then this should be discontinued 4 weeks prior to treatment.

We also do ask for a full history and blood test results to be e-mailed to us in advance of the treatment date in case there are any other issues that we need to assess. Dedicated referral forms can be found on our website.

We have appointments every two weeks on a Monday at 11am and 12pm. Patients are usually hospitalised for 5 to 10 days depending on the dose administered.

We order the I-131 on the day of the consultation so that we are able to “tailor” the dose to the individual patient assessment. Repeat evaluation of total T4 and creatinine is recommended one month after treatment. This can be chosen to be done at your clinic or BVSC.

There is a 14 day period after treatment where routine precautions need to be taken by the owners at home. A copy of these discharge instructions is below (for “Puss”).

I-131 Discharge Instructions

Puss has been treated with radioactive iodine for hyperthyroidism and is now safe to be discharged. However, for the next 14 days, Puss will be emitting and excreting a small amount of radiation in the urine and faeces and some precautions need to be taken
to ensure that any radiation exposure is kept to a safe minimum level. Large amounts of radiation can increase the risk of cancer and birth defects. However, following the instructions below, the risks from radiation will be negligible.

Avoid periods of more than a few minutes in close proximity to Puss. No sitting on the lap for more than a few minutes and no sleeping in your bed. No face to face contact or licking. Wash your hands after handling Puss, especially before eating. Please keep the supplied safety collar on for the 14 days.

Puss should only be handled in well ventilated areas. If Puss urinates, vomits or defecates in the house, this should be cleaned up with paper towels that are then placed in a rubbish bag. Use rubber gloves and wash your hands thoroughly afterwards. Urine soaked garments should be washed separately in a washing machine. Urine soaked carpets should be cleaned thoroughly.

If Puss uses a litter tray, keep this in an unoccupied area and use a waterproof disposable lining. Wear rubber gloves to clean the litter tray. Dispose of the litter in a sealed bag in the bin. Do not compost the litter.

Make sure Puss cannot jump onto the kitchen bench or get on anywhere that food is placed.

After this 14 day period, you can treat Puss as normal. Medication: No further anti-thyroid medication is necessary.

Revisits: A blood test should be performed in a month to re-check thyroid levels and kidney function.