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Radioiodine Therapy for Feline Hyperthyroidism

We love cats!

Thank you for your interest in radioiodine therapy at Oregon Veterinary Specialty Hospital. We are dedicated to providing the highest-level service to our feline patients, the owners who love them, and the primary veterinarians who work so diligently to take care of them. Our practice is limited to radioiodine therapy which allows us to focus solely on hyperthyroid patients. We are the only provider of radioiodine in Oregon at this time and take this responsibility seriously. We have a focused team of cat lovers working to take care of the patients that need this amazing treatment. We're here to help however we can.

Our Philosophy

Our philosophy at Oregon Veterinary Specialty Hospital is that "we treat cats, not thyroid glands". We want to help your cat to feel as well as possible for as long as possible, not just have a normal thyroid value. We will work with you and your primary care veterinarian to ensure that radioiodine and the testing surrounding the treatment fits in the best way into your cat's long-term health plan. We consider the entire case history and recommend basic overall health testing to make sure that we're making the best decisions for your cat.

Cat laying in a grassy field

Hyperthyroidism & Radioiodine

  • Hyperthyroidism is the most common hormonal disease of cats, affecting up to 10% of cats over the age of 10. The disease is caused by a benign overgrowth of thyroid tissue in 98% of cases, with fortunately only a few percent due to cancer (adenocarcinoma). The excess thyroid hormone puts significant and, if not treated, ultimately fatal stresses on the body. The heart and kidneys are two organs at particular risk of the damaging effects of high thyroid hormone.

  • Radioiodine therapy also referred to as I-131, is the safest and most effective therapy for hyperthyroidism.  We are able to cure 95-98% of cats of this debilitating disease, usually with a one-time injection under the skin of a small-volume solution that doesn't sting, similar to vaccine administration.  

  • Studies show that cats that receive radioiodine live longer and feel better having had their hyperthyroidism cured with radioiodine than cats maintained on medical therapy (methimazole) or a prescription diet (y/d.) These other treatments do not stop the abnormal tissue from growing or even converting to cancer.  Another positive point is that radioiodine often costs less than these other treatments over time. 

We are excited to offer this amazing therapy to your cat!

Cornell University

College of Veterinary Medicine

Please note - NY has different guidelines for aftercare than Oregon

Cornell University

College of Veterinary Medicine

Please note - NY has different guidelines for aftercare than Oregon

Veterinary Partner

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Our Staff

Diane Decker


Dr. Diane Decker was raised with 4 older brothers by animal-loving parents in rural upstate New York. They had many cats and dogs who were her best friends. She saw from a young age the power of a good veterinarian to help the lives of pets and their families. She was the first person to go to college in her family, graduating summa cum laude from Colby College in Maine. She graduated from Cornell University College of Veterinary Medicine in 2002 where she was the leader of the Cornell Pet Loss Support Team for 3 years. She then completed a small animal internship at the Regional Veterinary Referral Center in Alexandria, Virginia.

Dr. Decker worked first as a staff veterinarian at VCA 12 Mile Animal Hospital then was offered the role of Medical Director.

She held this position for 8 years, establishing and modeling standards for the highest level of care for her clients and patients. She transferred to VCA Raleigh Hills in 2019 to work closer to home and to join the I-131 team.  She became the director of the program in the fall of 2020.  She is excited to continue this life-saving work at Oregon Veterinary Specialty Hospital.

Dr. Decker has had a special interest in hyperthyroidism since veterinary school.  It’s a debilitating disease but happily one that we have so much power to help control and even cure. She has gone through radioiodine as a loving pet owner with two of her personal cats and brings this sensitivity to her practice. She has found her life’s passion in offering this amazing treatment to her feline patients and supporting the people who love them and the referring vets who take such good care of them. Her love for these special patients drives her dedication to the radioiodine program. Dr. Decker’s goal is to make the OVSH radioiodine program a premiere I-131 facility with expanded capacity and a focus on patient comfort and safety.

Dr. Decker lives in SW Portland with her husband and 5 cats. She enjoys anything sparkly, being warm, reading, hiking, college basketball (go Heels!), and cuddling with cats in the sun.

Preparations & Timeline

  • We are dedicated to treating and curing as many cats that need us at this beautiful, large facility.  Patients who are well-controlled on methimazole or y/d diet may take up to 2 months to work through the referral process (depending on case load, response to methimazole or y/d, coordinating schedules, etc), while we do our best to see patients who did not tolerate methimazole within a month. 

  • Please note that patients should be as stable as possible prior to being admitted to the hospital for post-radioiodine isolation.  Your cat may need to be on anti-nausea, anti-diarrhea or other supportive medications prior to radioiodine. 

Preparations & Timeline


Oregon Veterinary Specialty Hospital is pleased to provide you with a variety of forms that can simplify the process of caring for your pet.

You can view the forms in PDF format by downloading the free Adobe Acrobat reader.


COST: It’s essential to be aware that the total cost of this advanced medical procedure entails more than the injection and hospital stay itself.

  • Phone consult: $170 ­ 

  • Pre-radioiodine testing: if all pre-treatment tests and procedures are done at our clinic (not all are required), these could cost up to ~$1450 above the injection cost. ­ 

  • Radioiodine injection and hospitalization: starting at $1400 ­ 

  • Post-radioiodine testing at your vet. At least 3 visits with labwork and exam (varies per response). The cost is determined by your veterinarian’s pricing structure.

Referring Veterinarians

Forms and Information:

  • Quick referral Guide

  • Hyperthyroid diagnosis and testing

  • Gray zone kitties

  • Radioiodine and renal disease

  • IRIS Staging (attached)

Referring Veterinarians

Contact Us

  1. Every cat, client, and veterinarian is important to us. 

  2. The best way to contact us is to email us at [email protected]. We do our best to reply within 2 - 3 business days.  Please note our hours of operation.  

  3.  You are welcome to call (503) 616-2711 during our business hours if needed.  You may need to leave a message as we are often away from the phone with a client and patient care. 

  4. If your need is more urgent, please note that in your subject line, or call the main clinic at (503) 292-3001.

  5. If you need assistance when Dr. Decker is not in the office please see below.

  6. CLIENTS:  Please call your primary veterinarian with any health concerns. They have been sent guidelines from us for testing that is required and thoughts on follow-up if your cat is not feeling well post-radioiodine. 

VETERINARIANS:  Please consult with a local internist or an internist at your reference lab who offers free consultations.

Hours of Operation

(Subject to Change)

Diane Decker, DVM  Program Director, Radiation Safety Officer  (Mon, Tues, Thurs)

Team (Mon - Fri)


Browse our catalog of frequently asked questions and learn more about what to expect on your next visit.