For Veterinarians
Veterinarians: If you would like to consult about a patient or to see if your patient is a candidate for I-131, please email all medical notes and lab reports dating back at least one year prior to the hyperthyroidism diagnosis, along with your questions/concerns, to felinehtc@gmail.com. Dr. Mahoney considers multiple parameters on the physical exam, history, and lab work when considering candidacy.
1. Procedures to perform prior to referral: (ALL procedures, including the full physical exam, must be within 6 weeks of appointment with FHTC):
- Complete Physical Exam
- CBC
- Full Chemistry Screen
- Urinalysis
- A Non-Medicated T4 (done either as the original diagnostic T4 or after your patient has been off all thyroid specific medications, foods, and/or supplements for a full 7 days)*
- Blood Pressure (recommended, but not required)
Free T4s are typically not necessary. You are welcome to contact Dr. Mahoney to see if a Free T4 is advised.
*If your patient is currently taking Methimazole/Felimazole®, you are welcome to call our office so we can discuss the timing of labs for your patient. The true (non-medicated) thyroid hormone (T4) level that is less than 6 weeks old is needed to determine a treatment dosage of I-131.
2. How should I prepare my client?
Have your client read all sections of Essential Reading prior to scheduling
3. When can my patient be seen? How far out is scheduling?
On average, we can see and treat your patient within 2-3 weeks
4. What is the cost of treatment?
The cost ranges from $1,900.00 to $2,100.00, depending on what dose the cat receives. Our doctor will determine the dosage during the consultation with the cat and the owner.
5. What is the success rate of the treatment?
Over 95% of cats we treat are permanently cured of hyperthyroidism
6. Are you still scheduling at the Tacoma facility?
As of July 16th, 2026, we have made the decision to pause new bookings at our Tacoma location for the foreseeable future while we restructure our clinic operations.
Testimonials
My cat was diagnosed as hyperthyroid when she was 10. We had her treated as soon as she was diagnosed and I was glad it was found early. I didn’t really give the thyroid... read more
SavannahLynnwood, WA
Pox's Story Does it make sense to treat hyperthyroid in a fourteen-year-old, mostly outdoor cat? That’s what we were asking ourselves in the summer of 2013. Pox let me know his opinion by following me... read more
PoxSeattle, WA
Hello! Just wanted to let you know Rio Blanco is doing great! As soon as we got home he started emptying the bowls of food! I haven't even opened the anti-nausea or the... read more
Patrick and RioI wanted to drop you and everyone at FHTC a note to let you know that Byron (the PAWS™ kitty FHTC treated pro bono earlier this year) was adopted last month! Even better, he... read more
ByronSeattle, WA
Thanks to Dr Faythe Vaughan, and her kind staff in Shoreline and Tacoma for giving us at least 5 extra, good quality, years with our buddy, Rocky! He was a rescue cat to begin with, and his good... read more
RockyTacoma, WA
Great place. They were so good to my kitty who was really scared. He seems to be completely cured. read more
We want to thank you for your extraordinary efforts in looking after our Samson's well being. You took the initiative of a problem we were not aware was even present. We are very, very... read more
SamsonPort Townsend, WA
Dr. Vaughan; Kathy; Miranda; and anyone who was involved in treating and caring for Tigger. Just wanted you to see the life Tigger is leading because of your excellent care on this upcoming anniversary... read more
PepperThree months ago my 13 year old kitty Miss Fanny spent three days in the care of Dr. Vaughan and the staff. Before treatment she had been losing weight, getting more lethargic and her... read more
Miss FannyNorthbend, WA
You took care of our Nina Kitty and it was like she found the Fountain of Youth! At age twelve, she had been slowly losing weight and getting a bit more "yowly" but we... read more
NinaThey are very personable, professional, and knowledgeable about their very specialized practice. If you have a cat with thyroid issues, I highly recommend this clinic. read more
BeckySeattle, WA
Princess started losing weight and after checking with the vet she was confirmed as being Hyperthyroid. After Approximately 13 months of of a paste-like med applied to the ears, switching from left to right... read more
Monty is 12 years old. Dr. Vaughan had been monitoring Monty’s thyroid over the years and identified that he was borderline for hyperthyroidism. After discussing his overall appearance, behavior and appetite, we decided that... read more
MontyAs a member of an animal rescue organization on Vashon Island (VIPP), as well as being a chronic cat owner, I've had many opportunities to visit the Feline Hyperthyroid Treatment Center. Over the past... read more
Piro Kramar. Vashon Island Pet ProtectorsVashon Island, WA
My family has had Lila since she was a kitten. She is turning 15 in October, I was only 10 when we got her. I moved away as an adult for a few years... read more
LilaShoreline, WA
Will & Grace found me in 1999 when they were four weeks old. They were born near in a parking lot off Highway 99. They are twins and do everything together. This year they celebrated their... read more
Will, Grace, and HunterEdmonds, WA
Ripley (kitty) and I just wanted to thank Dr Vaughan and the whole staff for your great service and care. You were all great to work with, and communicated well with us! Ripley left... read more
Kali & Ripley