Cats are very stoical by nature. This comes from generations of life in the wild. Small felines—both predators and prey— instinctively hide signs of weakness lest they become someone’s lunch. This impulse is highly useful in the wilderness, but not so relevant to the modern cat’s lifestyle. A cat may keep her sickness a secret until her body can no longer cope. Suddenly, you have a very unhappy kitty on your hands.

Luckily, cats do give hints. The better you know your cat—her habits, appearance, and behavior—the more apparent they will be. Noticing sick signs and intervening right away could mean the difference between life and death.

The following are common sick signs in cats. This list is not exhaustive, nor is it a substitute for professional veterinary advice. Please note that these symptoms are more worrisome in a very young, very old, or otherwise frail cat, since they have fewer defenses when illness strikes. If your cat is doing something that worries you, always consult your vet.

Behavior change

If your cat’s temperament changes unexpectedly, she is probably telling you something. A friendly cat may turn reclusive; a playful cat becomes apathetic; an elderly cat stops jumping into your lap or sleeping on your bed at night. By contrast, a laid back cat may be hyperactive, needy or meowy when they’re sick. Since cats are such great pretenders, a behavior change may be your only clue.

Change in appetite

Changes in appetite are a classic sign of feline illness, although some don’t simply stop eating. They may just become picky, or switch from preferring dry food to craving only canned. Others may come running at the sound of the meal being prepared only to take one sniff and walk away. Note that a sharp increase in appetite could indicate trouble as well (i.e., hyperthyroidism or diabetes).

Increased thirst

This is a very important sick sign if you’re observant. Most cats aren’t big drinkers, especially if they eat a canned-food diet. If you see your cat begging at the faucet or hanging by the water bowl more than usual, this could be a sign of diabetes, kidney disease, hyperthyroidism, or a host of other problems. If your cat is drinking more, he should urinate more too. A soaked litter pan or urine accidents outside the box are reasons to call the vet.

Vomiting

Lets face it, some cats are vomiters—whether from hairballs, plant-eating or the classic “snarf and barf.” Repeated vomiting over a 24 hour period is not normal, and can indicate a serious infection or an intestinal blockage. Chronic, recurrent spit-ups are another concern, especially if accompanied by weight loss, lethargy, or diarrhea.

Straining to urinate

Bladder problems are quite common in cats. Typical signs include frequent trips to the litter pan, labored or painful urination, or bloody or discolored urine. Urine accidents outside the litter pan are another common indicator. Seek immediate veterinary care for a male cat who is repeatedly vocalizing and straining to void. He may have a life-threatening urinary blockage.

Breathing problems

The signs of respiratory disease can be subtle. Symptoms to watch for include cough, wheezing, shortness of breath, and shallow, rapid breathing. These sick signs could be serious if accompanied by additional symptoms such as lethargy, poor appetite or fever. Open-mouth breathing in a cat who is not overheated or stressed is a true emergency.

Fever

Conventional wisdom says to worry if your cat’s nose is warm and dry instead of cold and wet. This is not backed up by fact . Cats naturally feel warm to the touch because their body temperature runs higher than ours. Taking your cat’s temperature with a thermometer is the only real way to diagnose a fever (see box, below). Fever is an important sick sign that always warrants a trip to the vet.

Bad breath

All cats have fish breath; however an unusually foul odor may indicate a painful ulcer or tooth abscess. Problems such as kidney or liver disease can also cause bad breath. Drooling can indicate either serious oral disease, nausea or belly pain.

Dull coat

If your feline friend is looking like something the cat dragged in, there could be a problem. Cats frequently stop grooming when they’re feeling ill. The fur may appear spiky, matted or have dandruff. Liver, kidney, or intestinal disease, as well as simple dehydration, can make coat and skin look unhealthy.

Lumps and bumps

A tender localized swelling, particularly in outdoor cats, could be a bite wound abscess. Growths and tumors occur as cats age, and are often benign. But those that grow quickly, ooze or bleed, or are tender to the touch are sick signs that your vet should check without delay. This is especially true of growths that develop on a female cat’s belly. Breast cancer in female cats is all too common.

Lameness

A subtle lameness can be hard to detect in the average housecat, who lounges 18 hours per day. Be alert to obvious symptoms such as limping or refusal to touch a paw to the ground. More subtle signs include: a hitch in the stride, hesitation before jumping, or stiffness when rising or settling into a reclining position. Cats are so good at pretending nothing’s wrong, that if you see signs of lameness for more than 24 hours, it’s time to call the vet. Common causes of lameness are a sprain, fracture, infection, tumor, or arthritis.

Neurological signs

Weakness, stumbling, falling, head tilt, disorientation, loss of consciousness, seizures: these are all key neurological signs that should be checked by your vet immediately. Symptoms that come on suddenly could be signs of a stroke or intoxication and are true medical emergencies.

Unexplained weight loss

Finally, unexplained weight loss –where’s there’s been no diet or lifestyle change—is a subtle but important sick sign in cats. Many chronic feline ailments start with this one insidious symptom. Gradual trends are hard to spot when you see your cat every day. Stroke your cat over her back and hips. If these bones are more prominent than before, your cat may be losing weight.

Knowing your cat’s sick signs can help you and your vet intervene earlier, avoiding more serious problems and costly treatments down the road. You’ll have better peace of mind for all of your cat’s nine lives.