What is the best treatment option for Feline Hyperthyroidism?

Radioiodine treament is the safest and most effective therapy for Feline Hyperthyroidism available. The treatment involves a one-time, subcutaneous injection; nothing invasive. General anesthesia is not required for therapy, which eliminates a major risk factor for  geriatric cats.

What Is the Cost of Radioiodine Treatment?

The total cost* of the treatment is $1,755 to $1,955, which includes a consultation/physical examination ($190) by one of our veterinarians, and radioiodine treatment and hospitalization ($1,565-$1,765). The range in treatment fees is based on the dosage of I-131 that your cat requires. 

Your cat's dose can only be determined by examining the cat in person.

0.5 to 4.9 mCi.................$1,565.00 (80% of cats we treat receive less than 5.0 mCi.)
5.0 to 10 mCi..................$1,765.00

All fees will need to be paid in full on the day of your appointment. We accept all major credit cards, Care Credit, and cash (exact change only). Checks are not accepted.

*Further charges may occur if any additional tests are run or if medications are dispensed while your cat is in our care. 

How do I schedule an appointment?

We reserve a spot for the treatment on the same day as the consultation with our doctor to reduce car trips for your cat. However, if you prefer to schedule the consultation only, we are happy to accommodate that request. To begin the appointment scheduling process, please fill out this form in its entirety. Our review of your cats' medical records help determine whether your cat is a good candidate for I-131 treatment, and if so, what dose will be best. The final dose of I-131 is decided when we perform our physical exam during your cat's appointment with our facility.

Our Shoreline facility offers appointments on Mondays and Thursdays, and our Tacoma facility offers appointments on Tuesdays.

If your cat is arriving by air, we will want them to arrive no later than the day before treatment. We will give you the phone number of a courier service, which you can call and make arrangements to transport your cat to and from the airport. Courier transportation fees are billed separately and are your responsibility. 

Why Does My Cat Need To Be Scheduled at a Specific Location (Shoreline vs. Tacoma)?

If your cat meets any of the following criteria, they will be scheduled at the Shoreline facility:

  • Cats that are considered "medically fragile", i.e. have additional illnesses affecting the heart, the kidneys, etc., which is more likely in senior cats
  • Feral cats or cats requiring sedation to be examined
  • Cats with a T4 (thyroid hormone) level of 12 or higher. Cats with this severe degree of hyperthyroidism may have heart issues and/or other complications from this level of thyroid hormone, and this location is connected to a full-service veterinary hospital

If your cat has a T4 of less than 12 and is otherwise healthy, they will be scheduled for treatment at our Tacoma facility. This clinic is our satellite facility, designed to treat cats that require lower doses of radioiodine.

Our Shoreline clinic treats patients from all over the Pacific Northwest, as well as from Alaska and Hawaii. Therefore, severely hyperthyroid cats must be prioritized. If traveling to Tacoma is a true hardship for you, your cat (T4 less than 12) can be scheduled for treatment at our Shoreline location, however there may be a delay of up to 4 weeks*

*Please note: This delay in treatment could result in you having to obtain additional lab work prior to your treatment date. See the timeline below for requirements.

What procedures are needed prior to treatment?

The following procedures* must be less than 6 weeks old at the time of the appointment:

  • Complete physical examination
  • Full CBC
  • Full Chemistry Screen with Total T4 (off any thryroid medications/supplements for at least one week)
  • Urinalysis
  • Blood pressure (recommended but not required)

*If your cat is currently on Methimazole/Felimazole, y/d, or any other thyroid supplements, please call before having updated lab work done.

Is it possible that my cat is not a good candidate for radioiodine treatment?

To be candidates for radioactive iodine therapy, we request that all cats have screening procedures (physical exam, CBC, chemistry profile, T4, and urinalysis) and a blood pressure when possible performed by the referring veterinarian within six weeks of the treatment date. Cats with questionable kidney function may need testing within 1 week of the procedure. Cats with significant heart disease should be accompanied by the appropriate diagnostics. We will contact your veterinarian to request the medical records.

If your cat has significant kidney failure, advanced heart failure, or a malignant cancer, we can resolve the hyperthyroidism, but may be unable to make your cat better by treating the hyperthyroidism alone. You may not want to treat your cat due to the poor prognosis of the other disease processes, but we allow you to discuss this decision with your regular veterinarian prior to making any final decisions. 

Age is not a determining factor. We have treated many cats aged 15 years and older, and have even seen 21 year old cats who are in physically good shape do well with I-131 treatment. 

How long will my cat be in the hospital?

Once admitted for therapy, your cat legally cannot be discharged until their radiation exposure rate is at or below the level determined by the state. Cats will remain in the hospital as little as one night and as long as 10 nights. The average stay is 2-3 nights, but after the consultation when your cat’s dose has been determined, we will give you an estimate based on your cat’s treatment. Cats with high thyroid levels or very large thyroid tumors usually require larger iodine doses, and therefore may need to remain hospitalized longer.

My cat does not do well away from home. What do you do to keep cats comfortable?

As a feline-only facility, we are accustomed to catering to feline needs.

  • Since we see only cats, your cat will not be able to smell or see dogs, a common source of feline stress
  • Your cat is being cared for by doctors and staff that have specifically chosen to work with cats
  • Our hospital compartments are individually ventilated. All expired air is removed from the building. This decreases odors and stress pheromones, as well as decreasing the incidence of infectious respiratory diseases
  • The nuclear ward is separate from the main hospital making it a "quiet zone"
  • For especially nervous cats, we can provide a privacy curtain and/or a hiding box
  • We can also use Feliway, a feline pheromone, which has a calming affect for most cats
  • Fresh food and water are available at all times. Please inform us of any likes or dislikes or special dietary needs that your cat may have, so we can make their stay as comfortable as possible
  • We also offer safe anti-anxiety medications for your cat daily

May I visit my cat while in the hospital?

No, state regulations do not permit owners in the radiation ward. Toys or blankets from home are also not permitted because they would become contaminated and create more radioactive waste to be disposed of.

How will I find out about my cat's condition during hospitalization?

We will call you daily between 9:00 AM and 11:00 AM during your cats' hospitalization to let you know how your cat is doing, how they are eating, and whether or not they are able to be released that day.

When my cat is ready to come home, what do I have to do?

During the initial consultation, one of our doctors will provide you with a timeline specifically tailored to your cat. Always provide a pet carrier for your cats' safety and in case of bathroom accident. If your cat will be traveling by plane, one of our doctors will inform you at the initial exam when the anticipated discharge day will be. You will need to arrange the courier and the return flight. Charges for airfare and courier service will be taken care of by you.

If Your Cat Is On Thyroid Medication:

Do I need to stop the antithyroid medications (Methimazole/Felimazole®) prior to treatment?

Yes. They should be discontinued approximately 1 week before treatment. Exceptions can be made if your cat has serious cardiac disease. If this is a factor, you will be instructed by your veterinarian or by one of our doctors. If your cat can tolerate being without these medications for longer, then discontinue them even sooner. The antithyroid medications may decrease uptake by the abnormal thyroid tissue, and therefore will decrease its effectiveness. So, the longer they can be off these medications without compromising their health, the better.

Are there any medications or supplements I should avoid prior to therapy?

As previously mentioned, Methimazole/Felimazole®, as well as the y/d diet should be stopped 7 days prior to treatment.

Any supplements containing iodine, kelp (high in iodine), or are high in calcium or magnesium should be discontinued one week prior to therapy.

We have had some treatment failures in cats on holistic/herbal nutritional supplements, therefore we ask that supplements and additives not be given for 1 week prior to, and after treatment. Continue all prescriptions i.e. antibiotics, heart medications, and/or flea products as directed by your veterinarian.

What Precautions Do I Need To Take After Treatment?

For the first two weeks upon returning home, following these guidelines is advised to decrease your lifetime exposure to radiation. There are no health risks to you, your family, or to your other pets.

  1. Keep your cat indoors or under direct supervision or a leash if outside. The concern is that a roaming cat will come in contact with other people. They will not contaminate the earth with radioactive waste.
  2. We advise close contact (closer than 1 foot) should be limited to one hour per day. The dose you are exposed to is extremely low and will have no medical consequences. We are attempting to minimize your lifetime cumulative exposure.
  3. There is no risk for other pets. Your cat can share the litter box with other cats, can play, and sleep with other pets as usual.
  4. For this two week period the litter must either be scooped daily and stored or flushed (ONLY if using a flushable litter).

    TO STORE THE LITTER: Get a large bucket (5 gallon paint bucket) and line it with a trash liner. Scoop urine and feces into the bucket daily. At the end of the two weeks, the entire contents of the litter box should be emptied into the bucket. Put lid on the bucket and store in a garage, basement, or utility room for 80 days. DO NOT dispose of the litter prior to 80 days; garbage dumps have radiation detectors and will charge you a hefty fine if radiation is detected.
  5. Wash your hands carefully after handling your cat; litter pan and food dishes.
  6. Do not allow children or pregnant women to have contact with your cat.
  7. To minimize your lifetime cumulative exposure, we advise you against sleeping with your cat.

These precautions seem like my cat is hazardous to me. How safe is it?

The amount of radiation remaining in your cat is extremely low. A hyperthyroid person having radioiodine treatment typically receives up to up ten times the dose your cat will receive, goes home the same day treatment was given, and contact restrictions are limited to a day or two. The amount of radiation you might receive from exposure to your cat after they have been treated would be equivalent to the radiation received when you fly (atmospheric radiation) round trip across the country.

How quickly will this treatment cure my cat's hyperthyroidism?

Within 1 week to 3 months

At 1 and 3 months after the treatment, an exam and blood testing for thyroid and kidney function should be done by your veterinarian. The 1 month level thyroid may be slightly high, low, or normal. During this first month, your cat generally shows no side effects as it returns to its original pre-hyperthyroid status. A very rare cat may be mildly sluggish, sleep more, and eat less. Excessive shedding may also occur (rarely). These signs are all related to correction of the thyroid hormone imbalance. The 3 month T4 test should no longer be elevated. Any signs persisting after the T4 is back to normal are most likely due to other medical problems that need to be identified and treated by your veterinarian.

Holiday Hours

While we will care for any cats we have in our facility during any holidays, the face of our facility will be closed. 

Our clinic observes the following holidays:

  • New Year's Day
  • Martin Luther King Junior Day
  • Memorial Day
  • Fourth of July
  • Labor Day
  • Thanksgiving Day
  • Christmas Day

New Patient Center

Online Forms

Essential Reading

What To Expect

Alternative Payment Options

Care Credit




View All Testimonials