1-15 Lexington Rd, Underwood, QLD, AU, 4119
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Subtle Behaviour Changes in Cats That Could Indicate Illness
Most cat owners know exactly what their cat looks like when they’re annoyed, hungry or demanding attention. Sick is harder. Cats are masters at acting normal when they’re not feeling normal at all.
Often, the earliest signs of illness are small behavioural changes that appear gradually over time.
At Cat Specialist Services, we provide specialist veterinary care in a modern, cat-exclusive hospital. We see a wide variety of conditions, but many start the same way. Tiny inconsistencies.
A change in routine, personality or habits that gets brushed off as ageing or another known issue.
Changes in appetite and drinking habits
Cats may have a talent for hiding pain, but one thing owners can often spot by paying close attention is a change in food or water intake. For illnesses like kidney disease and hyperthyroidism, this can be one of the earliest clues. And we’re not just talking about obvious refusals to eat or drink, though those are certainly concerning. It’s the smaller differences that tend to fly under the radar.
Some cats start eating more slowly, others may leave part of their meals behind when they’d usually guzzle it all with haste. They may suddenly prefer softer foods, chew differently or show a bit of interest in the food before backing away. This may indicate dental pain, nausea or a myriad of other potential underlying causes for discomfort.
Drinking habits matter, and they’re one of the changes you can keep track of at home. If you’re refilling the water bowl more often or finding your cat there constantly, they’re probably drinking more than usual. Increased thirst can be associated with several common feline conditions, like diabetes.
Altered grooming and coat condition
Cats are known for their consistency when it comes to grooming, so any changes in this space should be noted. If your cat is overgrooming by repeatedly licking or chewing the same area, they may eventually develop hair thinning or bald spots. Potential causes of excessive grooming include stress and anxiety, but it can also mean allergies, skin irritation, parasites and pain.
On the flip side, reduced grooming can lead to a greasy, scruffy or matted coat. Some of the underlying causes of this are arthritis (due to limited movement), obesity, general illness, fatigue or pain.
Any other changes in coat quality can also suggest a cat isn’t feeling quite right. Fur may start looking duller, rougher or thinner than usual due to things like skin disease, stress, poor nutrition or illness elsewhere in the body. Dandruff can also become more apparent in cats that have reduced their grooming.
Hiding, withdrawal and social shifts
Cats are moody. That can be perfectly normal. But sometimes stronger personality differences can be due to discomfort or illness. Cats experiencing stress or pain may spend more time hiding under beds or avoiding busy family areas. Pain can also reduce interest in social interaction, play or attention because they feel uncomfortable or vulnerable.
But not every cat withdraws when they’re feeling ill. Some become unusually clingy and want constant reassurance from their people. Others increase vocalisation, particularly older cats. This can be linked to anxiety, discomfort or cognitive decline.
A different sleeping location or a sudden desire to stay close to you is also relevant information to share with your vet.
Differences in normal tolerance levels are another thing to watch out for. A cat who would usually enjoy being handled but starts pulling away, flinching or reacting negatively to touch likely has a reason for that. Painful areas commonly include the back, hips or abdomen, which may make cats less comfortable with patting or being picked up. Increased tension around other household pets or general irritability at home may seem purely behavioural, but physical discomfort can absolutely be part of the reason.
When sleep activity and mobility are not the same
It’s easy to look at your cat and envy their life of luxury, lazing around and sleeping whenever it pleases. But because cats already spend so much time resting, activity and mobility changes can be easy to miss in the early stages. Illnesses that impact energy levels can include kidney disease and hyperthyroidism.
Restlessness, pacing or wandering after dark can sometimes be linked to pain, anxiety or cognitive decline in senior cats. Other things to watch for at night include increased vocalisation and litter tray issues, such as accidents outside the tray or difficulty getting in and out, which may point to urinary trouble, arthritis or discomfort.
Mobility issues are often gradual rather than dramatic. Hesitation before jumping onto furniture or climbing stairs may be an early sign of arthritis or joint pain. Some cats may even stop accessing their favourite elevated resting spots completely. And going back to grooming issues, restricted movement can contribute to that too.
When your cat doesn’t seem quite like themselves
Caring for someone who can’t speak up when they’re suffering is a big responsibility. And cats are very good at hiding it from you anyway. But when you do notice the little signs of the things they can’t say out loud, listen to them. It’s always worth a conversation with your vet to see whether illness or injury could be the cause.
If your cat has been behaving differently and further investigation or specialist care is needed, your vet can arrange a referral to Cat Specialist Services.
“When you do notice the little signs of the things they can’t say out loud, listen to them.”
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 subtle changes in cats can indicate illness?
Early signs of feline illness are often behavioural rather than dramatic physical symptoms. Changes in appetite, drinking habits, grooming, sleeping patterns or social behaviour can all suggest that a cat is uncomfortable or unwell.
Why would a cat suddenly start drinking more water?
Increased thirst can sometimes be associated with common feline health conditions such as kidney disease or hyperthyroidism. Owners may notice they are refilling the water bowl more often or seeing their cat drink more frequently than usual.
Can changes in grooming habits mean a cat is unwell?
Yes. Overgrooming may be linked to stress, allergies, parasites, skin irritation or pain, while reduced grooming can result in a greasy or matted coat and may be associated with arthritis, obesity or illness. Changes in coat quality can also reflect broader feline health concerns.
Why is my cat suddenly hiding or acting differently around people?
Cats experiencing pain, stress or illness may hide more, avoid interaction or become less tolerant of handling. Some cats react in the opposite way and become unusually clingy or vocal, particularly older cats experiencing discomfort or cognitive decline.
What mobility changes should cat owners pay attention to?
Gradual hesitation before jumping, avoiding stairs or no longer accessing favourite elevated spaces may be early signs of arthritis or joint pain. Restlessness at night, litter tray difficulties and reduced activity levels can also indicate discomfort or underlying feline health issues.
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
Subtle behavioural changes in cats can sometimes indicate underlying health issues.
Increased thirst or appetite changes may signal common feline medical conditions.
Grooming and coat changes can reflect pain, stress or reduced mobility.
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