Signs your cat is sick: the changes cats hide

Cats are quiet about being unwell by design. As a small animal that is both a hunter and, to something bigger, prey, a cat that looked weak in the wild risked losing a meal or becoming one, so the species learned to carry on as normal well after a problem has taken hold. On your couch that instinct has not switched off. The practical result is that feline illness tends to show up late and in small print, in a few skipped meals, a little more time spent hidden, a coat that looks slightly unkempt, or a change in the litter box, rather than in anything dramatic. Learning to notice those early is worth far more than waiting for a sign no owner could miss.

A word on how to use this page. It pulls together what veterinary sources say about the signs of illness in cats, so you can watch your own animal and judge when to act. It cannot examine your cat, it does not diagnose anything, and it is not a substitute for a veterinarian who can do both. The ranges below are typical figures from veterinary references, not fixed cutoffs for your individual cat, so treat them as a guide and confirm what is normal for your animal with your own vet. Any sign that genuinely worries you is a reason to call your veterinarian, who knows your cat's history, or an emergency clinic when it will not keep. The same instinct that makes cats good at hiding illness is exactly why patient, unglamorous vigilance is the most useful thing an owner can offer.

Learn what a well cat looks like

You cannot register a change without a starting point, so learn your cat's healthy normal while it is healthy. A typical cat body temperature is about 100.5 to 102.5°F, with a reading above roughly 104°F or below about 99°F worth a vet's attention (VCA). A resting heart rate in cats runs faster than most owners expect, roughly 140 to 220 beats per minute in a calm animal, well above a dog's. A relaxed or sleeping breathing rate usually sits under about 30 breaths per minute, and a rate that stays consistently above that while your cat is at rest is a reason to call. Healthy gums are pink and moist, and when you press a fingertip against them the color should return in under about two seconds. None of this is worth measuring in a panic. It is worth knowing on an ordinary day, because that baseline is what lets you recognize trouble later.

Appetite and thirst, the first dials to move

The earliest feline warning sign is usually the bowl. A cat that turns away from a food it normally wants, eats noticeably less over a day or two, or suddenly begins begging for far more, is telling you something even while it still looks fine. Appetite matters more in cats than many owners realize, for a reason specific to the species: a cat that stops eating for more than about 24 to 48 hours, especially an overweight one, can develop hepatic lipidosis, a serious fatty-liver condition that turns a skipped-meals problem into a medical one (Cornell Feline Health Center). That is why feline loss of appetite is handled with more urgency than a dog missing a meal. If your cat has not eaten properly for a day, do not wait it out, call. Knowing how much your cat should be eating in the first place, covered in our guide to how much to feed your cat, makes a drop easier to catch.

Thirst is the other early dial, and it moves in both directions. A clear, sustained jump in how much your cat drinks, or in how often and how much it urinates, is one of the more common first hints of kidney disease, diabetes, or an overactive thyroid, all of which turn up more often in middle-aged and older cats (Cornell Feline Health Center). Because many cats take a good share of their water from food, a change is easier to miss if you feed wet, which is one of the trade-offs weighed in our look at wet versus dry cat food. A cat that starts emptying the water bowl or camping by the faucet is worth a mention to your vet even if nothing else seems wrong, because these diseases are far easier to manage when they are caught early.

Weight that slips away under the coat

Cats lose weight quietly, and a full coat hides it well, so pounds can come off for weeks before anyone notices by looking. Gradual, unplanned weight loss is one of the more reliable signals that something is off, and it rides along with several of the diseases already mentioned, plus dental pain and gut problems. The way to catch it is by hand rather than by eye. Run your fingers along the ribs and spine every so often and notice if they feel sharper than they used to, or lift your cat and pay attention to whether it feels lighter than it did. Even a loss that seems small matters on a small animal: shedding half a pound off a ten-pound cat is roughly five percent of its body weight, the equivalent of a meaningful drop in a person. A home scale check every month or two, on a good day, gives you a number to compare against, which beats trusting your memory of how heavy the cat felt in your arms.

Reading the litter box

The litter box is one of the most honest health readouts a cat owner has, which is a good argument for scooping it yourself rather than automating the job away. Watch for changes in volume and frequency: much larger or more frequent urine clumps can track with the thirst changes above, while smaller and fewer point the other way. Diarrhea, hard and infrequent stools, straining to defecate, or blood in either is worth a call, and no stool at all for a couple of days with obvious straining warrants one sooner. A cat that suddenly starts going outside the box is often flagging a medical problem rather than a behavioral grudge, so a new habit of peeing on the bath mat deserves a vet visit before a scolding; our guides to why a cat avoids the litter box and setting up a litter box walk through the overlap between medical and setup causes.

One litter-box change sits in a category of its own and gets its own section below: a cat, most often a male, straining in the box while producing little or nothing. Make a mental note of it now, because it is the feline emergency that owners most often mistake for simple constipation.

Coat, grooming, and the shifts in behavior

Cats are fastidious groomers, so grooming is a useful gauge. A coat that turns dull, greasy, matted, or unkempt often means a cat has stopped grooming because it feels unwell or hurts too much to twist and reach, while the reverse, obsessive licking that thins the fur in one patch, can point to pain, itch, or stress. Hiding is the classic feline tell: a cat that retreats under the bed, adopts a new and out-of-the-way spot, or simply withdraws from the household is usually coping rather than sulking. Watch too for a cat that suddenly resents being touched or picked up, sits hunched with its feet tucked and eyes half closed, sleeps far more than usual, or stops jumping to the perches it used to favor. As with every sign here, a shift away from your particular cat's normal patterns carries more weight than any single behavior on its own.

• Appetite: eating less, refusing a favorite food, or a sudden jump in hunger.
• Thirst and litter box: drinking or urinating noticeably more, or noticeably less.
• Weight: a gradual loss you feel over the ribs and spine before you see it.
• Coat: a dull, greasy, or matted coat, or over-grooming one patch bare.
• Behavior: more hiding, less jumping, hunched posture, or new resistance to handling.

The male-cat emergency that hides as constipation

If you take one thing from this page, take this. A cat straining in the litter box while producing little or no urine may have a blocked urethra, a true emergency that is far more common in males because their urinary passage is longer and narrower. It develops when crystals, a plug, or inflammation seal off the flow; urine backs up, and a fully blocked cat can deteriorate and die within about 24 to 48 hours as the kidneys and bloodstream are overwhelmed (Cornell Feline Health Center). The signs are easy to read as constipation, which is exactly the trap: repeated trips to the box, squatting and straining with nothing or only a few drops appearing, crying or howling in the box, licking at the genitals, restlessness, vomiting, and hiding. A cat doing this needs an emergency clinic now, not in the morning.

Females can block too, just far less often, so the sex of your cat lowers the odds without erasing them. The reason this one earns its own heading is the speed paired with the disguise: it looks like a mild problem, it is not, and the window to fix it is short. If you are ever unsure whether your straining cat is constipated or blocked, let a veterinarian make that call rather than watching at home, because guessing wrong can cost a day the cat does not have.

Two checks that take seconds: breathing and gums

Two quick checks tell you how serious a situation is, and both take seconds. The first is breathing. Count the breaths while your cat rests or sleeps by watching the chest rise and fall; a resting rate that sits consistently above about 30 per minute is abnormal and worth a prompt call (VCA). Genuine breathing difficulty is a separate, higher category and is always an emergency in a cat: fast or labored effort, the belly heaving with each breath, and above all open-mouth breathing or panting, which is normal in a dog but a warning sign in a cat that is not overheated or freshly exercised. A cat breathing with its mouth open needs care immediately, never a wait-and-see.

The second check is gum color, your fastest read on circulation and oxygen. Lift the lip and look: healthy gums are pink and moist (VCA). Pale or white gums can point to blood loss, shock, or the anemia that sometimes shadows chronic disease, while blue, grey, or muddy gums signal a lack of oxygen, and a yellow tinge can mean jaundice. Any of those is a reason to go now rather than to monitor. If the gums are not their usual pink, or the color is slow to return after you press them, that is your cat asking for help before it can show you anything more obvious.

Watch, call, or go

Not every off day is an emergency, and treating each one like one helps nobody, so it helps to sort signs into three responses, summarized in the cards below. A single mild, isolated change in a cat that is otherwise bright, eating, drinking, grooming, and moving normally is usually a monitor-then-call situation over a day or so. Anything that repeats, combines with other signs, or clearly involves pain moves up to a same-day call to your vet. The true red flags belong to an emergency clinic straight away.

Two practical notes. Call ahead when you can: AAHA advises phoning your veterinarian or the nearest emergency center when you are worried, which lets them prepare and tell you what to do on the way. And for anything you suspect your cat swallowed, alongside getting to a vet you can reach the ASPCA Animal Poison Control Center at (888) 426-4435, staffed around the clock, though a consultation fee may apply. Cats are unusually sensitive to some common toxins, including lilies, which can cause fatal kidney failure, and human medicines such as acetaminophen, so save that number before you need it. The minutes before you reach a clinic are covered in our pet first aid basics, and the same read-the-signs logic applied to dogs lives in signs your dog is sick.

A short list of figures to remember

Habits that catch problems early

The feline emergencies that cannot wait

Cat-owner questions, answered