1-15 Lexington Rd, Underwood, QLD, AU, 4119
SEARCH
Before and after radioactive iodine treatment for cats with hyperthyroidism
Sometimes, you have to see it to believe it. Radioactive iodine therapy is the gold standard treatment for cats with hyperthyroidism and the only curative solution. However, if you’ve not been in this position before, it may seem too good to be true. We sat down with Dr Rachel Korman to talk about the before, during and after of the process, and we’ve got some real patient case studies to share with you.
At Cat Specialist Services, our radioactive iodine facility in Brisbane offers world-class I-131 treatment. Every part of the hospital has been designed to support a comfortable stay and a low-stress recovery for our beautiful feline patients. Let’s take a closer look at the process and the results we’re seeing.
Before treatment, and the impact of hyperthyroidism on cats
Hyperthyroidism doesn’t always make itself obvious straight away. By the time a cat ends up at the hospital, the changes have often been building quietly for a while.“I think for a lot of owners, because it can often be a fairly gradual process, they’re not always aware of how far down the track those cats have gone,” says Dr Rachel Korman.
The clinical picture just prior to treatment is frequently a picture of an anxious, overstimulated and physically depleted feline. They may pace continuously, struggle to rest and show some signs of distress. “It’s like if you gave 20 cups of coffee to a toddler,” Dr Rachel explains. “That’s how they behave.”
Beyond behaviour, there’s the physical toll the condition takes on a cat. Weight loss is common, and in some cases severe, often seen alongside vomiting, diarrhoea and a dull, greasy coat. The constant activity can aggravate arthritis, particularly as this is a condition we typically see in older cats, and this further reduces their comfort. Some can even become reactive and aggressive, which is inconsistent with their usual temperament. That’s why it’s such a relief to welcome them into the hospital, where they can finally start heading toward a better quality of life.
What it looks like during treatment
The stay itself can last anywhere from a week to just over three, depending on the cat’s needs and whether they come in for medical boarding. However, as Dr Rachel explains, “Often the hardest thing is just for owners to get their cats to the hospital. Catching them at home can be the hardest thing.” Once they’ve arrived and had time to settle, most cats cope far better than their owners expect.
Routine plays a big role in that adjustment. Predictability helps cats feel safe, and over time they begin to treat the hospital as their own space.
Patients can often be seen waiting at the front of their runs for breakfast, greeting staff and falling into familiar patterns. “They’re totally at home,” Dr Rachel says. “You can kind of see the way they interact… their routine is predictable and that’s really what a lot of cats love.”
Because an admission for I-131 isn’t a rushed visit, the team at CSS has time to build meaningful relationships with each patient. They learn who likes what, who prefers their medication in food, and who needs a bit more space or reassurance. It’s not just treatment. It’s feline care shaped by compassion and understanding.
Recovery and life after treatment
Once thyroid levels begin to settle, the difference in a cat’s demeanour is usually quite striking. The anxiety fades. Sleep returns. They’re more at ease in their bodies and more present in their surroundings. “Owners love it because they start getting their old cat back,” says Dr Rachel. “They’re calmer, less anxious, less worked up.”
The physical improvements tend to follow. Appetite returns. Coats become cleaner and softer. Behaviour transitions into something more familiar, less reactive and more affectionate. For many, it also brings relief from other issues that have either developed with age or been worsened by the thyroid disease itself, from gastrointestinal problems to heart changes. In some cases, follow-up scans even show measurable cardiac improvement. Dr Rachel recalls one patient whose heart wall thickness had “almost gone back to normal” just three months after treatment.
For many families, one of the most meaningful changes is being able to stop dealing with daily medications. Some cats were previously on a cocktail of thyroid, cardiac and anti-nausea drugs up to twice a day. “Owners can just be owners,” Dr Rachel says. “Not tablet givers.” And that simple change often brings the best kind of relief for everyone involved.
Meet Bubba McNamara
Stacey first noticed something was off when Bubba, her usually relaxed indoor-outdoor cat, started hunting. It wasn’t like him. He’d also begun asking for food earlier in the day, and more often than usual. “He’s always been a hungry boy,” Stacey said, “but this was different.”
Fortunately, Stacey caught the changes early and, after discussing options with her vet, decided on I-131 treatment at Cat Specialist Services.
The change after treatment was clear. Bubba was more content, the hunting stopped, and his appetite settled back into its usual rhythm. His weight stabilised, and he returned to his easygoing self.
“It was a good experience, and I definitely recommend I-131. Even though others offer it, I recommend CSS. Everything from start to finish was just great.”
Dr Rachel recalls Bubba arriving a little anxious but settling in quickly. “He really relaxed into the environment,” she said. “By the end of his stay, he’d gained a few hundred grams and was eating well. He just looked really comfortable.”
“Sometimes, you have to see it to believe it.”
Meet Kikki Cekalovic
Kiki had been living with poorly controlled hyperthyroidism, made more difficult by a suspected drug reaction and fluctuating thyroid levels on transdermal medication. Her case was further complicated by heart changes, which were picked up during her initial assessment. The team worked closely with a cardiologist to stabilise her before treatment, and she responded exceptionally well in hospital. Her three-month follow-up scan showed significant improvement.
Meet Kuro Chen
A calm and gentle older cat, Kuro had been managed medically for some time before his treatment. He had fluctuating T4 levels and a benign heart murmur, which was cleared by the cardiology team, and he went on to have a smooth stay. His thyroid levels normalised, and he gained nearly a kilo during his admission and he no longer needs ongoing heart medication.
Radioactive iodine treatment is life-changing for hyperthyroid cats and their owners
Radioactive iodine is a safe, non-invasive treatment that gives hyperthyroid cats a chance to return to who they were. For many, it means better health, more comfort and a calmer, medication-free life. “They start getting their old cats back,” says Dr Rachel. After months of managing a slow and stressful decline, that return is something families remember.
At Cat Specialist Services, we’ve administered this therapy to countless cats, and we never tire of seeing them regain their health and personality. The many before and after stories are deeply rewarding, and they’re exactly why we continue to do this work.
If you would like to learn more about our world-class radioactive iodine facility, speak with your regular vet about a referral or contact us at Cat Specialist Services today.
If you’re a veterinarian managing a cat with hyperthyroidism, you can refer them for specialised care 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 changes should I expect in my cat before and after radioactive iodine treatment?
Before treatment, most cats with hyperthyroidism show symptoms like weight loss, increased appetite, restlessness, and poor coat condition. After radioactive iodine treatment, we typically see a gradual return to normal behaviour—weight stabilises, appetite balances out, and their coat improves. In many cases, cats start looking and acting like themselves again within a few weeks to months as thyroid levels normalise.
Why choose radioactive iodine over ongoing medication?
It’s a one-time, curative treatment that removes the need for daily pills and ongoing management, which improves life for both cats and their owners.
Is radioactive iodine treatment safe for cats?
Yes, radioactive iodine (I-131) is considered the gold standard treatment for feline hyperthyroidism. It’s a targeted therapy that only affects abnormal thyroid tissue, leaving the rest of the body largely unaffected. It’s also non-invasive and avoids the need for surgery or long-term medication.
Why does my cat need to stay in hospital during treatment?
After receiving the radioactive iodine injection, your cat will need to stay in a specialised facility for several days while radiation levels decrease to a safe level. This is a safety requirement, not because your cat is unwell. During this time, they are closely monitored and cared for until they can safely return home.
Will my cat need ongoing medication after radioactive iodine treatment?
In most cases, no. Radioactive iodine is a one-time treatment that cures hyperthyroidism in the vast majority of cats, eliminating the need for daily medication or special diets. However, we still recommend follow-up blood tests to ensure thyroid levels remain stable and to monitor overall health.
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 treatment is considered the most effective cure for feline hyperthyroidism.
A single treatment targets abnormal thyroid tissue without damaging healthy cells.
Many cats experience dramatic improvements in health and quality of life after treatment.
Cat Specialist Services Reviews 
on 
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