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A closer look at radioactive iodine treatment for cats at CSS
A cat lounging by the window, eyes half-closed in contentment, is the picture of feline vitality. However when that same cat becomes restless, withdrawn and loses weight despite an insatiable appetite, hyperthyroidism may be the culprit. This common endocrine disorder typically affects older cats and causes a cascade of health issues if left untreated. While medications and dietary adjustments can help manage symptoms, only radioactive iodine treatment offers a cure.
At Cat Specialist Services in Brisbane, we provide premier radioactive iodine treatment in a world-class, cat-exclusive facility designed with feline comfort in mind. We love helping cats overcome this condition and return to full health. We spoke with Dr Rachel Korman about why radioactive iodine is the gold standard treatment, and what makes CSS the trusted choice for cat families.
What is radioactive iodine therapy, and why is it the best option?
Hyperthyroidism in cats occurs when a benign tumour in the thyroid gland overproduces thyroid hormones, accelerating metabolism and causing significant health issues. Radioactive iodine therapy (I-131) is a safe, curative, effective and minimally invasive treatment.
“The thyroid is really the only gland in the body that uses iodine,” explains Dr Rachel Korman. “So the radioactive iodine is absorbed directly into the thyroid and acts very locally to destroy the overactive parts without damaging anything else.”
Unlike medication, which requires lifelong administration and frequent monitoring, or surgery, which carries anesthesia risks and potential complications, radioactive iodine therapy provides a definitive solution. “If I had to choose for my own cat,” Dr Korman says, “there’s no way I’d want to be giving tablets twice a day for the rest of their life. Not only is it stressful for both the cat and the owner, but over time, the medication dosing changes as the thyroid tumours grow, so there needs to be re-evaluation and blood tests.”
Are there cases where my cat might not be a good candidate for radioactive iodine therapy?
Most hyperthyroid cats are suitable for this treatment, but some conditions may make it unsafe. Severe heart disease can be a significant risk, as stress from hospitalisation can worsen a fragile heart condition.
“In some cases, we work with our cardiology team to stabilise cats with medication before treatment,” explains Dr Korman. However, in rare cases, the risk remains too high to proceed.
Occasionally, other serious illnesses, such as intestinal cancers, are detected during screening. “If we find a bigger problem is causing the weight loss, we won’t proceed with the radioactive iodine,” says Dr Korman. Each case is carefully assessed to determine whether treatment is safe and appropriate.
What if my cat has other health issues?
Hyperthyroid cats are often older and may have manageable underlying conditions such as mild heart disease or kidney concerns. At CSS, we’re equipped with on-site specialists to ensure these cats are stabilised and carefully monitored before, during and after treatment.
Even if your cat has other health concerns, it’s always worth discussing I-131 therapy with us. With the right approach and expert oversight, many cats with co-existing conditions can still receive safe and effective treatment.
Can you explain the procedure step by step?
Before treatment, each cat undergoes a thorough medical review and physical examination to assess overall health and rule out contraindications, such as advanced heart or kidney disease. We typically perform blood tests to determine thyroid hormone levels and ensure there are no other underlying conditions that could affect treatment.
Every cat’s condition is unique, so the iodine dose is tailored specifically to their thyroid hormone levels and goitre size. “We put all of that together to determine the iodine dosage that’s specific to that individual,” explains Dr Rachel Korman.
On treatment day, the cat receives a single capsule of radioactive iodine, administered the same way as a worming pill. The iodine is quickly absorbed by the thyroid gland, where it begins selectively destroying the overactive tissue while sparing healthy cells.
Cats stay in our purpose-built, spacious isolation units for around a week, and we closely monitor them to ensure their health and comfort.
Once the radioactivity levels have safely decreased, patients can return home. Owners must follow temporary precautions, like keeping their cat indoors and limiting close contact for a couple of weeks. If this isn’t feasible, our medical boarding services are available.
How does a feline-only facility make a difference?
“Cats are so attuned to their space and routine,” says Dr Rachel Korman. “Even just hearing dogs can be stressful, which is why a cat-only setting makes a real impact on their recovery.”
How do you make the isolation period comfortable for cats?
Radioactive iodine treatment requires a short isolation period, and it’s important for families to know their cats are comfortable during their stay. At CSS, we focus on creating a clean, comfortable environment that doesn’t involve self-shielding kennels, where waste can accumulate and lead to unpleasant conditions.
“At CSS, we built everything with the cat’s experience in mind. Our isolation units are spacious and clean and have separate waste storage with dedicated ventilation, so there’s no lingering smell. They also have natural skylights and cat TV for enrichment,” says Dr Korman.
“Cats receive a single treatment that targets overactive thyroid tissue.”
Is the experience tailored to the needs of each cat?
Every cat responds differently to hospitalisation, which is why the team at CSS adjusts care based on individual needs. “The nursing team puts so much effort into understanding what each cat likes—whether it’s a specific type of food, bedding, or just adjusting their space to make them feel more secure,” says Dr Korman.
What are some common concerns and misconceptions about radioactive iodine therapy?
Many assume radioactive iodine treatment is expensive, but while there is an upfront cost, it proves to be far more cost-effective in the long run. “If you calculate the cost of daily medication, blood tests, and increasing doses over the years, radioactive iodine actually ends up being the cheapest option by miles,” says Dr Korman.
Radioactive iodine is a well-regulated, low-risk therapy. Some people mistakenly believe it poses significant risks. “This is a treatment humans receive, too,” says Dr Korman. “Cats just need a short isolation period to ensure safety, but after that, the risk is minimal.”
Talk to the cat specialists at CSS
If your precious cat has been diagnosed with hyperthyroidism, radioactive iodine therapy offers a curative solution. Our specialist-designed facility ensures each patient receives a thorough assessment, with on-site access to cardiology and other experts for a seamless treatment process.
At CSS, our cat-exclusive clinic is designed for comfort and minimal stress, giving every cat the best chance at a smooth recovery.
To learn more about our radioactive iodine services, contact our team today. Vets can refer patients for treatment here.
Are you worried about your cat’s health?
If you are concerned about your cat, please reach out to our friendly team. Call us on 1300 228 377 or fill out the contact form below. In an emergency, please contact your local vet.
For vets – to refer a patient or book a telehealth consultation, please call us on 1300 228 377, book through the portal or fill in the form.
Meet The Author
Dr Rachel Korman
Specialist in Feline Internal Medicine
BVSc MANZCVS (Internal Medicine) FANZCVS (Feline Medicine)
Dr. Korman’s childhood love for cats led her to veterinary medicine, and early on, it was clear that feline care was her calling. After graduating from the University of Queensland in 2000, she worked in small animal and feline-only practices across Australia and the UK.
She received a Senior Clinical Training Scholarship from the Feline Advisory Bureau (now International Cat Care) at the University of Bristol, where she researched feline infectious and haematological diseases, and in 2018, became a Fellow of the Feline Medicine Chapter of the Australian New Zealand College of Veterinary Scientists and a registered Feline Medicine specialist.
Frequently Asked Questions
What is radioactive iodine treatment for cats?
Radioactive iodine therapy is a treatment for hyperthyroidism in cats. A small dose of iodine targets and destroys overactive thyroid tissue.
Why is radioactive iodine considered the gold standard treatment?
It directly targets abnormal thyroid cells while leaving healthy tissue largely unaffected. This approach can cure hyperthyroidism in many cats.
What happens before radioactive iodine treatment?
Cats undergo a full veterinary assessment, including blood tests and sometimes imaging. These tests help confirm the diagnosis and check for other health conditions.
Why do cats need isolation after treatment?
Following treatment, cats remain in isolation while the radioactive iodine levels decline. This precaution protects both caregivers and other animals.
How successful is radioactive iodine therapy for cats?
Most cats achieve normal thyroid hormone levels within weeks of treatment. Ongoing monitoring ensures hormone levels remain stable.
Patient Stories
Our commitment to feline health is best seen in the stories of the cats we’ve had the privilege of treating. These journeys highlight the dedication, expertise and compassion that drive us.
Each patient faced unique challenges, and it was our honour to offer high-quality care and help them regain strength and happiness. We value the deep bonds with cats and their owners, knowing the difference we make in their lives.
Kitty, a lymphoma survivor
We first met Kitty after she was referred to CSS for the evaluation of a large intestinal mass
Poppi finds her feet again
Following surgery to remove a hairball obstruction, Poppi was referred to us at CSS as she had not bounced back as expected
Rusty and his ongoing chronic rhinitis journey
Lifelong nasal issues, including persistent discharge and breathing noise, have been a bit of a thorn in Rusty’s side.
Lando’s long game with cryptococcus
Lando was referred to CSS because he had a swelling under his jaw that wouldn’t go away.
Popeye coughs up the culprit
Ares is a handsome young Maine Coon who was referred to CSS after presenting at AES with sudden lameness in his back leg.
Key Takeaways
Radioactive iodine therapy is a curative treatment for hyperthyroidism in cats.
The treatment targets abnormal thyroid tissue responsible for excess hormone production.
Cats typically stay in isolation for several days following treatment for safety monitoring.
Cat Specialist Services Reviews 
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Tanya Bell
6 months ago
We transported our cat here from another animal hospital, as his condition was too complex for them. Our pet was given the highest quality of care, multiple investigations/procedures being able to be done at the one place a godsend. We were kept up to date frequently throughout his stay. All questions & options explained thoroughly. Being able to have private visits certainly helped us and our cat too. I would highly recommend Cat Specialist Services at Underwood. Amazing staff from reception, vet nurses, vets & specialists. Oh, and yes he is recovering wonderfully at home.
Melinda Cox
A month ago
So very happy we were asked to come here for advice for our NORBIT. He has had 2 x UTI blockages within weeks of each other since turning 6. Surgery seemed to be his only option and he didn’t feel it was very fair on him if we didn’t at least exhaust all other avenues first.
Dr Allison was very thorough in her tests and has let us know she would like to treat the cause of the problem. Great news.
It may lead to removal of crystals in his bladder if his diet doesn’t let him pass them naturally.
At least this surgery won’t be as severe at taking his penis off him – so as his fur parents – we are very happy with this.
We await further tests to see what’s in store for him.
NORBIT will now be a patient of the clinic as we are so far very happy with his treatment thus far.
Lesley Rosekrans
A month ago
Hi has only been a week since losing my beautiful Peaches but can’t thank Dr Cindy, Maree and Jackie enough for the tender care they gave her and they after care they gave me. I sincerely thank them and can’t recommend the Clinic highly enough they are such caring people. Peaches I’m happier times.
Madison McEwan
A month ago
I cannot thank the entire CSS team enough and especially Dr Cindy for the care they provided for our boy with a urinary blockage, and we will be taking both our cats here from now on. The clinic is exceptionally clean and calming compared to all other clinics we’ve been too, and all staff from the reception to the nurses/vets were so supportive during a stressful time. I knew from the first minute that I got to see him after he was transferred that he was in the best place, and that the staff genuinely care about their well-being and positive long term outcomes. We were given regular updates and full transparency, so much information including QR video codes on how to administer medications, along with print outs and emails about how to best help avoid future issues or recurrence. Our boy got to smooch on everyone and was beyond well looked after. Thank you again, you all made an incredibly stressful situation actually manageable and calming.
Astrid El Gamal
6 months ago
Dr Wan-Ju has been treating my baby since her first seizure in November 2025 and she has been fantastic.
Everybody at the clinic is so friendly and caring and I know my baby is in good hands.
Thank you team!
Deeba M
3 months ago
Dr Alison Jukes from CSS Underwood is an AMAZING feline physician. She is kind, professional, thorough and our cat is blessed to have her on his side. She even was able to save us money and invasiveness by being skilled to the level of doing ultrasound on two separate occasions without our cat needing to go under full sedation. Our other cat was recently seen by Dr Jukes as well, and she made sure our cat’s heart was ok. I also want to thank the lovely Jacqueline and Mairead from customer care. They are very kind each time I see them and call up. Sending thanks from our family, including Smokey and Floozy!
Judith Dionysius
A month ago
My whole experience with CSS was positive – from the first email I received giving lots of information regarding the process of radioactive iodine treatment to the expected costs, to checking my cat in for the treatment, boarding for 2 weeks after the treatment and picking her up to come home. They didn’t push for any tests that were not necessary.
Janelle Wieden
5 months ago
We never knew this service existed but we are very grateful we were referred to them. Our vet Cindy was really great, she made us feel at ease during a very stressful time. We got the sense straight away the Leo was in good hands. This service made us feel better knowing that they specialise is cats only. Would highly recommend their services
Georgia Carter
5 months ago
My Lani finished her I-131 treatment today and I am beyond impressed with the way she was looked after. I am by definition a neurotic pet owner and sending my fur child away for a week was seriously daunting.
I was given daily updates about how kitty was eating, toileting and behaving. This really put my mind at ease. Vets and vet nurses were so accomodating and allowed Lani to have her favourite foods from home prepared her favourite way.
Her vet was so thorough when explaining her treatment and condition to me.
The ladies at reception were so friendly and understanding.
I honestly cannot recommend this clinic enough and I am so thankful for the positive experience Lani and I have had.
Lauren Woodward
A year ago
My sweet ginger boy Louis was hospitalised at CSS for a Urinary Obstruction. Dr Cindy and all the reception staff were amazing and empathetic. I would often ring up with questions post procedure and Dr Cindy would make time to talk and explain things to me
Service Locations
Cat Specialists accepts referrals for cats across Brisbane and surrounding regions, working closely with local veterinary clinics to provide specialist diagnosis, treatment, and ongoing management.
Contacting Us
Pet Owners
If you would like to talk about treatment for your cat, call us on 1300 228 377 or fill in the form.
In an emergency, please contact your local vet.
Vets and Nurses
To refer a patient or book a telehealth consultation please call us on 1300 228 377, book through the portal or fill in the form. For advice calls, please see the guidelines here.
Monday-Friday: 8 am-6 pmSaturday/Sunday - Closed