Most pet cats will deal with the same short list of health issues over a lifetime. Knowing what the common ones look like — and which ones can wait until Monday morning versus which ones need a vet today — saves a lot of worry and a fair amount of money. Cats are also very good at hiding illness, so the real skill isn't diagnosing; it's noticing that something has shifted and acting on it.
This is the overview. The deeper guides linked below cover each problem in more detail.
Digestive issues
The most common complaints owners bring to the vet are vomiting, diarrhoea, and hairballs.
- Hairballs are normal in small numbers — once or twice a month for most cats, more for long-haired breeds. Frequent hairballs, or hairballs with retching that produces nothing, point to a problem.
- Vomiting that happens once and the cat bounces back is rarely serious. Vomiting more than twice in a day, vomiting with lethargy, or any vomit that's bloody or coffee-coloured needs a same-day call.
- Diarrhoea lasting more than 48 hours, or any diarrhoea in a kitten or senior cat, warrants a vet visit. Bring a stool sample.
Litter box trouble
A cat that stops using the box reliably is telling you something. The cause is usually one of: a urinary tract issue, stress, a dirty or poorly-placed box, or a litter the cat dislikes. Work through the non-medical causes first, but if you see straining, blood in the urine, or a male cat going to the box repeatedly without producing anything, treat it as an emergency. Litter box problems covers the full diagnostic order.
Dental disease
By age three, most cats have some degree of dental disease. It's the single most under-treated issue in pet cats because the signs are quiet — bad breath, slow eating on one side, occasional pawing at the mouth. A yearly oral exam catches it before extractions are needed.
Weight problems
Roughly half of indoor cats are overweight, and the consequences — diabetes, arthritis, urinary disease — are all worse than the weight itself. The fix is portioned meals, not free-feeding, and a vet-set target. A pound off a ten-pound cat is meaningful.
Skin, ears, and parasites
Fleas, ear mites, and ringworm are the regulars. Itching, head-shaking, hair loss in patches, or black grit in the ears are the usual tells. Monthly preventatives handle most of it; the rest is a quick vet visit.
Hidden pain
Cats almost never cry out when they hurt. What you see instead is behavioural: hiding, reduced grooming, a hunched posture, reluctance to jump, or sudden irritability. Signs your cat is in pain covers what to look for. If you're not sure whether something is off, that uncertainty is itself a reason to book a check-up.
Chronic conditions in older cats
Past age ten, the common ones are kidney disease, hyperthyroidism, diabetes, and arthritis. All four are manageable when caught early, which is why senior cats should see a vet twice a year. Watch for increased thirst and urination, weight loss with a good appetite, or a cat that stops jumping to favourite spots.
When it's an emergency
Some symptoms can't wait. When to go to the emergency vet covers the full list, but the short version: difficulty breathing, collapse, seizures, suspected poisoning, severe trauma, a bloated abdomen, or a male cat straining to urinate. None of these get better on their own, and the cost of waiting is much higher than the cost of the visit.
Building the habit of noticing
The owners who catch problems early aren't more medically knowledgeable — they handle their cats often enough to notice small changes. A daily brush, a weekly weigh-in, a look in the mouth once a month. The vet handles the diagnosis; your job is to flag that something is off, and the sooner the better.