By Priya Nair RVN · Last updated 19 May 2026
Cats are masters at hiding pain. Evolutionarily it makes sense — a sick cat is a predated cat — but as owners it means we often see them at the vet far later than we should. By the time a cat is “obviously” unwell, the problem is usually weeks old. This pillar is the vet-nurse cheatsheet I hand new cat owners: what to watch for, what counts as “vet in 24 hours”, what is “vet now”, and what is “drive yourself to the emergency clinic”.
Pair with our kitten care pillar and cat diet master list — diet and life stage drive a lot of the symptoms on this page.
The three-tier triage
- Emergency now (drive to vet ER): blocked urination, breathing difficulty, collapse, seizure, suspected poison, hit by car, prolonged vomiting in a kitten.
- Same-day vet (call your clinic, get seen today): not eating 24+ hours, repeated vomiting, severe lethargy, limping, eye discharge, persistent diarrhoea.
- Vet within 2-3 days (book an appointment): weight loss, drinking more than usual, intermittent vomiting, behaviour change, lump under skin, dental smell.
Urinary blockage — the single fastest killer
If a male cat is straining in the litter tray and nothing is coming out, it’s an emergency. Feline lower urinary tract disease (FLUTD) can block the urethra completely. Without treatment a blocked male cat dies within 48-72 hours from kidney failure and electrolyte derangement. We see it most in young desexed males, especially overweight ones on dry-only diets.
- Watch for: repeated trips to the litter box with no urine, crying in the box, blood-tinged urine, licking genitals obsessively, vomiting (electrolyte sign).
- Action: emergency vet immediately. Cost of unblock + 2-3 day hospitalisation typically $2-4k. Skip the next-morning appointment instinct — hours matter.
- Prevention: wet food (not dry-only), fresh water in multiple locations, ideal body weight, litter tray rules (n+1 boxes, clean daily).
Vomiting — what’s normal vs not
Cats throw up a hairball every couple of weeks. That’s normal. Almost everything else isn’t.
- Once a fortnight, hairball, otherwise normal: normal. Brush more.
- Once a week or more, even with hair in it: not normal — book a vet appointment for blood work. Often early sign of inflammatory bowel disease or hyperthyroidism.
- Multiple times in 24 hours, no hair, lethargic, off food: same-day vet. Could be foreign body, pancreatitis, or toxin.
- Projectile, repeated, with abdominal pain (hunched posture): emergency. Intestinal obstruction is a real possibility — especially if they swallowed string, hair tie, or ribbon (a “linear foreign body” is a surgical urgency).
- Vomiting with blood / coffee-grounds appearance: emergency — gut ulcer or worse.
Drinking and toileting changes
An adult cat normally drinks 50-60ml per kg per day. Most of that comes from wet food. A cat that is suddenly emptying the water bowl, hanging around the tap, or drinking from puddles outside is signalling a real problem.
- Increased thirst + increased urination + weight loss + good appetite: diabetes (very common in middle-aged overweight cats).
- Increased thirst + increased urination + weight loss + bad appetite: chronic kidney disease (extremely common in cats over 10).
- Increased thirst + ravenous appetite + weight loss + restlessness: hyperthyroidism — also a common older-cat condition.
- Sudden onset polydipsia/polyuria: always vet within 2-3 days. Early diagnosis dramatically extends life expectancy on all three above.
Weight loss — the slow-motion emergency
Cats hide weight loss under thick fur. A cat that has dropped a kilogram looks the same in photos. Buy a postage scale or weigh yourself first then with the cat — once a month, log it.
- Healthy 4kg cat losing 200g a month = 5% body weight = serious.
- Common causes: hyperthyroidism, diabetes, kidney disease, IBD, lymphoma (the big four older-cat diseases).
- Action: vet appointment with bloods + urinalysis. Weight loss alone justifies it.
Not eating — when 24 hours matters
An adult cat that misses 24-48 hours of food is at real risk of hepatic lipidosis — a form of fatty liver disease specific to cats where the liver can’t keep up with the metabolic demand of fasting. Obese cats are at highest risk and the disease itself can kill if not aggressively treated.
- Kitten: 12 hours of no food is the threshold. Hypoglycaemia is real, especially under 6 months.
- Healthy adult cat: 24 hours = call the vet. 48 hours = same-day appointment regardless.
- Overweight cat: never let it skip more than 24 hours without vet contact.
- Older cat: 24-48 hours = vet appointment. Reduced appetite is often the first sign of CKD, dental disease, or cancer.
Breathing trouble — read the chest, not the noise
Cats don’t normally pant. A cat panting at rest is in respiratory distress and that’s a “drive now” emergency. Count breaths per minute when the cat is relaxed — normal is 20-30, anything above 40 at rest needs investigation.
- Open-mouth breathing — emergency.
- Belly heaving with each breath — emergency.
- Persistent dry cough — asthma in younger cats, heart disease in older cats — vet appointment.
- Wheezing + nasal discharge — cat flu (herpes/calici), needs treatment.
- Bluish gums or tongue — emergency, hypoxia.
Dental disease — the silent cause of “old cat acting old”
By age 3, around 70% of cats have some periodontal disease. Cats with mouth pain eat less, lose condition, and behave grumpily — and the cause is hidden behind closed lips.
- Bad breath that’s actually bad (not just “cat food smell”) — gingivitis.
- Dropping food, chewing on one side — sore tooth.
- Drooling, especially blood-tinged — broken tooth or resorptive lesion.
- Pawing at the mouth — foreign body or dental pain.
- Action: vet dental check + scale-and-polish under anaesthesia. Most adult cats need one every 1-3 years.
FIV and FeLV — the viruses to know
- FIV (feline immunodeficiency virus) — feline equivalent of HIV. Spreads mainly through deep bite wounds, so risk is highest in roaming, intact tomcats. FIV-positive cats can live normal, long lives — they just need a stable indoor home and prompt vet attention when sick.
- FeLV (feline leukaemia virus) — more dangerous, spread via saliva and shared bowls. Australian prevalence is low but real. Vaccinate kittens at risk.
- FIP (feline infectious peritonitis) — historically a death sentence, now treatable with antiviral GS-441524. Suspect in any young cat with persistent fever, weight loss, abdominal effusion, eye changes. Get to a referral centre — the protocol is real and works.
Toxin exposure — what to do
If you know the cat ate something toxic — lily, paracetamol, antifreeze, rat bait, snail bait — call the Animal Poisons Helpline (1300 869 738 in AU/NZ) immediately. Don’t wait for symptoms. Don’t induce vomiting at home in cats unless a vet tells you to.
- Lilies — eating a leaf, drinking vase water, even grooming pollen off fur is lethal. Acute kidney failure. Vet now.
- Paracetamol (Panadol) — cats lack the enzyme to metabolise it. A single tablet is fatal. Emergency.
- Ibuprofen, aspirin, ivermectin (some forms) — also dangerous.
- Antifreeze — sweet-tasting, lethal. Even tiny licks.
- Permethrin (in some dog flea treatments) — cats lack the metabolic pathway. Never use dog flea products on cats. Emergency vet.
Behaviour changes — they mean something
Cats don’t get sulky for no reason. Sudden behaviour shifts are almost always medical.
- Hiding more than usual — pain or fever.
- Aggression in a normally calm cat — pain, especially dental or arthritis.
- Going to the toilet outside the litter box — urinary tract infection, blockage, anxiety from a change at home, or dirty box.
- Excessive grooming in one spot — pain, allergy, parasite, or stress.
- Confusion, vocalising at night, getting lost in the house — feline cognitive dysfunction in older cats, hyperthyroidism, hypertension.
Dehydration — the skin-tent test
Lift the skin between the shoulder blades into a tent and let go. In a hydrated cat it snaps back instantly. In a dehydrated cat it stays tented for a couple of seconds. Combined with sticky/dry gums, sunken eyes, and lethargy, dehydration is a “same-day vet” sign — and an emergency if the cat is vomiting or has diarrhoea on top.
FAQ
How often should an indoor adult cat see the vet? Annual wellness exam, including weight and dental check. From age 8, every 6 months with blood work because the chronic diseases creep in.
My cat is purring — does that mean she’s fine? No. Cats also purr when stressed or in pain — it’s a self-soothing behaviour. Read the whole body, not just the purr.
Pet insurance — worth it? Yes, especially for kittens. The big surgical emergencies (blockage, foreign body, cruciate rupture, FIP treatment) all run $3-10k. The premium ($30-60/month) is much less than the saved bill if you ever cash a claim.
Where to next
If your cat’s a kitten, the kitten care pillar covers the first-year medical milestones. For older cats, the next read is our cat diet master list — diet drives a huge proportion of the chronic conditions on this page. And for understanding the behaviour shifts that signal pain, see cat behaviour decoded.
Sources: ISFM Feline Welfare Standards, AAFP Senior Care Guidelines, Australian Animal Poisons Helpline materials, RSPCA AU veterinary protocols.
Page last updated 19 May 2026. We re-check our pet-care content regularly and update when something changes.
