How does radio iodine therapy work?

Iodine is an element required for normal health. In the body, it is used primarily by the thyroid gland (which is located in the neck) to produce the thyroid hormone.

Radio iodine is a form of iodine that has been made radioactive. In its radioactive state, it undergoes a natural process (decay) in which it gives off radiation. The radiation given off consists of three types: alpha, beta, and gamma. The half-life of I-131 is eight days. In other words, one half of the radio iodine goes through this process every eight days.

When taken into the body, a large percentage of radio iodine accumulates in the thyroid gland. The remainder of the I-131 is excreted in the urine and feces. Once the radio iodine is taken up by the thyroid gland (or thyroid tumor in a hyperthyroid cat), the gamma rays and beta particles are releases. The beta particles are particularly lethal to the thyroid tumor cells. The beta particles travel a maximum of 2-5 mm in tissue; therefore, beta-particles are locally destructive but spare adjacent hypo plastic thyroid tissue, parathyroid glands and other cervical structures. The radiation destroys the thyroid tumor cells and thus treats the hyperthyroid condition.

How do I know if my cat is a candidate for receiving radio iodine treatment?

Before pursuing radio iodine treatment, your veterinarian will perform a full physical examination and run blood work. It is also required that your cat has a urinalysis performed as well as two radiograph views of the chest. Blood work enables veterinarians to screen for other disease processes to ensure your cat is otherwise healthy. A urinalysis will allow your veterinarian and our treating veterinarians to gauge how well your cat’s kidneys are working. Poor kidney health may not exclude your cat from receiving treatment, but it will change the dose your cat receives of the radio iodine. Chest x-rays or radiographs will screen for any masses in the lungs. Hyperthyroidism is caused by a tumor of the thyroid gland. Although most cats have a benign (non-cancerous) tumor, if there are masses present in the lung a malignant tumor of the thyroid gland may be present. If your veterinarian is suspicious of this diagnosis, they can consult with a radio iodine trained veterinarian for further guidance.

Are there side effects to radioactive iodine treatment?

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 (such as cobalt radiation). Some cats seem to experience mild discomfort of the thyroid region at the beginning of therapy, but this resolves itself spontaneously and does not cause a problem.

Occasionally, a cat will develop hypothyroidism (under-active thyroid gland) after treatment with radio iodine. Cats can typically tolerate low thyroid levels without supplementation in many cases.

Overall, side effects of radioactive iodine treatment are extremely rare.

Can hyperthyroidism reoccur after being treated with radio iodine?

Yes, although it is very uncommon and occurs in less than 3% of cats treated. In addition, such reoccurrences usually develop three years or longer after the hyperthyroidism was first treated. Such relapses may indicate the development of a new thyroid tumor causing the recurring hyperthyroidism, rather than a relapse from the first tumor that was treated with radio iodine.

How is the radio iodine dose administered?

The radio iodine is given as a single dose on the day your cat is admitted to our treatment facilities for care. The radio iodine dose is compounded into an oral pill and administered by a nuclear-trained licensed veterinary technician.

What if my cat is currently being medically managed and I am interested in pursuing radio iodine treatment instead?

If your cat is either being managed with Methimazole/Tapazole/Felimazole or prescription diet and you have decided to pursue the radio iodine treatment the following needs to be done:

• Consult with your veterinarian before stopping medication or prescription diet
• Call our treatment centers to coordinate the necessary diagnostic testing and to schedule an upcoming appointment.
• Once your cat has been off the medication or prescription food for two weeks, then blood work is redone. This allows our treating veterinarians to get an idea of the hyperthyroid state without the medication in the system.

Does the radio iodine treatment always work to cure feline hyperthyroidism?

Our studies have shown that a single dose of radio iodine is effective in curing hyperthyroidism in over 98% of cats that are treated. Even the 2% of cats that are not completely cured after one treatment do show some lowering in their circulating thyroid hormone concentrations and improve significantly clinically.

If hyperthyroidism persists for longer than three to six months after treatment, re-treatment with radio iodine is generally recommended to cure the disorder. Virtually all cats that remain hyperthyroid after the first treatment are cured after the second treatment.

Is radio iodine safe for people to be around?

Radio iodine is a radioactive material, but with our training and offered owner training, is safe when owners and veterinary professionals are educated and “smart” when dealing with the nuclear patients. Our staff takes special precaution to be safe and are well trained to provide safety tips to owners for at-home care.

Due to the half-life of the radio iodine, your cat will be at its highest radioactive level while in our treatment facilities.

In fact, your cat will be measured and only discharged if radioactive levels are at a safe level for at home isolation. The remaining radioactivity in your cat will gradually disappear over 2-4 weeks after discharge (through radioactive decay and excretion into urine). The level in which your cat is discharged is much lower that the levels at which human patients are discharged from the hospital.

What is involved in the actual treatment with radio iodine?

After your cat has been diagnosed with hyperthyroidism by your veterinarian, you will be given options to either medically manage the disease, or treat the hyperthyroidism with radio iodine therapy. A phone consultation is done with one of our treatment centers to ensure your cat is a candidate for treatment. Records will be sent to our treatment centers and a dose specific to your cat will be ordered to arrive on the day of the scheduled appointment. On the day of your appointment, you will have a 1 hour consultation with the treating veterinarian. Your cat will be examined and then admitted into the radio iodine treatment centers for four days. The first day in the hospital, the veterinary staff will administer the radio iodine dose that was ordered specifically for your cat. Our highly trained veterinary staff will then care for and monitor your cat until the time of discharge. At discharge, your cat will be examined again and another consultation will occur, making sure there are no questions regarding the at-home isolation period. Your cat will then need to be isolated in a room in your home for a period of 1-2 weeks.

What is the isolation period?

If your cat has stayed in a treatment facility for the typical 4 day period, your cat will be discharged into your care and will need to be in isolation at home for 1-2 weeks. Isolation periods after treatment are a requirement by the NRC because your cat is still emitting low levels of radiation at discharge.

A one week at home isolation period is required for cats that live in an environments free from persons under the age of 18 and/or pregnant women. For those households with children and/or pregnant women- the isolation period is 2 weeks.

The isolation room needs to be a room in the house that is separate from living quarters. Owners are asked to spend minimal time in the isolation room, as patients are still emitting a low level of radiation. A spare bedroom or second bathroom are typically the most popular isolation rooms. Inside the isolation room, simply provide your cat with a litter box, food and water. When attending to your cat in its isolation room, wear latex gloves. The litter needs to be flushable. Flushable brands of litter can be found a pet stores. Also the litter box should have a liner inside. Wearing latex gloves, scoop the litter box as needed making sure to flush all urine and feces. Wash hands like normal after removing latex gloves. Urine and feces cannot be placed in the trash while in the isolation period. If this is done, both the owner and treating facility will be fined by the government. After 1-2 weeks of isolation, your cat is then able to return to all areas of your home.

What do I need to do the day of treatment?

If your veterinarian does not have digital x-ray and has not already emailed our treatment facility chest radiographs, you will have to hand carry the film copies of the x-rays to your appointment. Whoever will be caring your cat while in the isolation period should attend the consultation appointment. Important information regarding safety and care will be discussed during this consultation. Please bring your cat in a carrier to the treatment center at the scheduled time of your appointment. We also recommend bringing food your cat is accustomed too, as well as any medications your cat may be on. You may feed your cat the day of treatment, but we do ask no food 1 hour prior to transporting as some feline patients experience nausea in the car (especially longer car rides). Your cat will be fed after they receive their radio iodine treatment. After the consultation, the treating veterinarian will perform a physical examination and your cat will then be given their radio iodine dose and admitted to the hospital for monitoring for four days.

Can I bring anything for my cat?

Your cat should be brought in a carrier- this will be necessary for transport back to your home after discharge. If your cat eats a particular kind of food, we suggest that you bring portions of that so as not to interrupt your cat’s normal eating habits. Treats are allowed and will be given freely to your cat. Any medications prescribed by your veterinarian also need to be brought. Personal items (such as beds, towels or toys) cannot be placed in your cat’s cage due to the risk of contamination.

Can I visit my cat while they are hospitalized in a treatment center?

Due to the nature of the treatment, visitation is not permitted. You may, however, call as often as needed to check on the status of your cat. Cats are monitored two to three times daily by licensed veterinary technicians and the treating veterinarian.

What should I expect at discharge from a radio iodine therapy center? Will be my cat need any follow-up care after radio iodine therapy?

Two weeks after discharge from one of our treatment facilities, your cat should return to your veterinarian for a full physical examination and to have blood work done to verify the success of treatment. Follow up examinations should continue at least every 6 months as part of their on-going health care plan for your cat.

What is the cost of treatment for radio iodine therapy?

The current fee for Radioactive Iodine varies based on the dose . I-131 doses are ordered to the specific needs of individual patients. Please call one of our treatment facilities for pricing information.

Cost of treatment includes:

• Owner Consultation and safety training by nuclear trained veterinary staff members.
• 1 hour appointment with the treating veterinarian to describe in detail the treatment and after care.
• Full physical exam by the treating veterinarian.
• Radioactive iodine dose ordered specific to the needs of your cat. The doses arrive at our facilities the day of your cat’s treatment and cannot be used for any other patient.
• Administration of radio iodine dose by veterinary professionals
• In hospital care in our treatment facilities. This includes food and litter. Optional boarding for extended stay is an additional cost.
• Close monitoring of patients currently in the nuclear treatment rooms both by treating veterinarians and trained licensed veterinary technicians.
• Daily safety checks of the nuclear portion of hospital
• In depth discharge of patient back into owners care by a licensed veterinary technician.
• Medical chart will be sent to your veterinarian upon patient discharge from our facility.

Tests required prior to treatment (blood work, urinalysis and chest radiographs) are not included in this price.

When considering the cost of treatment, keep in mind in 98% of patients, this one time treatment is curative. With other medical management (such as administration of methimazole or use of the prescription diet) frequent veterinary follow up exams as well as the monitoring of blood values is required. Also medical management must be done for the life of the cat and will never CURE the hyperthyroidism but only manage it. In some cases, one year of medical management will cost almost the same as a single treatment of radio iodine.

Payment is due in full the day of treatment to the treating facility and methods of payment may vary based on location. Please view our locations sections for specifics of payment options.

Is there a cancellation fee for radio iodine treatment?

Each dose ordered is ordered specifically for an individual patient. Treating veterinarians will decide the dose based on diagnostics performed by your veterinarian. Please note, because each radio iodine dose is specific to individual patients, a cancellation fee of $250.00 will be charged for appointments canceled less than 48 hours before the appointment time.