Cat Health Warning Signs: What to Watch, and When to Act

Short answer

• Cats hide illness, so small changes count. Hiding more, eating less, drinking more, or using the litter box differently are often the first signs that a cat is unwell or in pain.
• Not eating needs a prompt call. A healthy adult cat that eats little or nothing for about 24 hours should be discussed with a veterinarian the same day. Call sooner for a kitten, a senior cat, or a cat with a known condition such as diabetes or kidney disease.
• Straining to urinate with little or no urine is an emergency. A blocked urethra, most often seen in male cats, can become life threatening within 24 to 48 hours. Do not wait overnight.
• Breathing changes are urgent. Open mouth breathing, labored breathing, or blue, gray, or pale gums need emergency care at once. Repeated coughing or wheezing needs a prompt appointment.
• Blood in the urine does not always mean infection. Bladder inflammation without infection, stones, and blockage can all cause it. Antibiotics help only when a bacterial infection is present, so testing comes first.
• Weight loss is a sign, not an answer. Losing weight while eating normally can accompany an overactive thyroid, diabetes, kidney disease, intestinal disease, or dental pain, and always deserves an examination.
• Behavior change needs a medical check first. Hiding, overgrooming, night vocalizing, or avoiding the litter box can reflect pain or illness as well as stress, so rule out medical causes first.
• This guide is general information only. It cannot diagnose your cat. Emergency signs need emergency care, and any change that worries you is worth a call to your veterinarian.

Introduction

Cats are good at hiding illness. A cat that seems only a little quieter than usual, drinks a little more, or skips one meal may already be unwell, and a cat that withdraws and stops eating may need help the same day. Because the early signs are often small changes in routine rather than dramatic symptoms, owners who know their cat’s normal habits are usually the first to spot that something is wrong.

This guide brings together the warning signs that matter most: changes in eating, drinking, urination, breathing, weight, movement, grooming, and behavior. It explains what each pattern can be linked to, what to observe before you call, and which signs need emergency care now rather than a routine appointment. It also explains the limits of home checks. A gum check or a skin lift can add information, but neither one can confirm or rule out a problem on its own.

This article gives general information only. It does not diagnose any individual cat, and it does not replace an examination. The same sign can have several causes, and only a veterinarian who examines your cat, and runs tests where needed, can find out which one applies. Where this guide gives a time frame, treat it as a reason to call sooner rather than later. If you are unsure how urgent a change is, calling your veterinarian and describing what you have seen is always a reasonable step.

Why Cats Hide Illness, and Why Baselines Matter

A cat that feels ill or painful often becomes quieter rather than louder. An animal that shows weakness is vulnerable, and domestic cats keep much of that instinct. At home it shows up as withdrawal: sleeping in a different place, hiding under furniture, resisting handling that was previously tolerated, or losing interest in food, play, and company. None of these changes names a disease. Together, they tell you the cat’s normal pattern has shifted, and that shift is worth reporting.

This is why a rough baseline helps. Owners who know how much their cat usually eats and drinks, how many urine clumps appear in the litter box each day, how the cat breathes at rest, and what the cat weighs can describe a change precisely. “Eating half of normal for two days, drinking more, and producing larger urine clumps” gives a veterinary team far more than “seems unwell.” A short note on your phone when something changes, plus a monthly weight, is enough for most households. In multi cat homes, watch individuals at feeding time, because a shared bowl can hide one cat eating much less.

Hiding and Not Eating

A cat that hides and stops eating may be stressed, painful, nauseated, or ill. Stress from a move, a new pet, visitors, or building work can make a cat withdraw and eat less. So can pain, dental disease, urinary problems, kidney disease, diabetes, pancreatitis, liver disease, fever, digestive illness, or a swallowed foreign object. Loss of appetite is a sign, not a diagnosis, so the cause still has to be found.

Before you call, check the basics if your cat allows safe handling: breathing, any vomiting, gum color, whether the cat has urinated, and any possible exposure to a toxin or a foreign object such as string. Seek emergency care for breathing trouble, collapse, repeated vomiting, or straining without producing urine. Otherwise call your veterinarian promptly, especially if little or no food is eaten for about 24 hours. Kittens and cats with diabetes, kidney disease, or another chronic condition may need care sooner. AAHA senior pet guidance likewise treats a cat not eating for more than 24 hours as a reason to seek immediate care.

One reason appetite loss matters so much in cats is the liver. When a cat stops eating, the body moves stored fat toward the liver for energy. In cats, that fat can accumulate inside liver cells faster than the liver can process it, a condition called hepatic lipidosis, or fatty liver disease. The Cornell Feline Health Center notes that hepatic lipidosis is almost always preceded by a period of anorexia, that in more than 90 percent of cases it follows another underlying condition such as obesity, diabetes, pancreatitis, kidney disease, or an overactive thyroid, and that it can be fatal if not reversed promptly. Overweight cats are at particular risk, so never put a cat that has stopped eating on a crash diet, and never start a weight loss diet without veterinary guidance.

Do not force feed your cat, and do not give human medications unless your veterinarian specifically instructs you to do so. Gently warming the cat’s usual wet food to increase its aroma is reasonable, and calm hand feeding may help some cats, but stop if the cat turns away or becomes distressed. Note when the cat last ate a normal meal, whether it is drinking, whether it has urinated and passed stool normally, and any recent change in food, medication, plants, or household products.

Appetite, Thirst, and Weight Changes

Changes in thirst and appetite often arrive together, and the litter box usually confirms them. A cat that drinks much more will normally produce larger or more frequent urine clumps. That combination, increased thirst with increased urination, is one of the most useful early patterns an owner can report, because it appears with several common conditions that blood and urine tests can separate.

Diabetes is one of them. When a cat’s body does not produce insulin properly, or does not use it properly, sugar builds up in the blood and spills into the urine, drawing water with it. The Cornell Feline Health Center describes four classic signs of diabetes in cats: increased appetite, weight loss, increased urination, and increased water consumption. The weight loss happens even though the cat eats well, because the body breaks down fat and protein stores for energy it cannot get from sugar. In later or poorly controlled diabetes, some cats develop hind leg weakness and walk with their hocks closer to the ground than usual. These signs do not confirm diabetes. Kidney disease and an overactive thyroid can look similar, and stress at the clinic can temporarily raise blood sugar, so diagnosis rests on examination plus blood and urine evidence of sustained high glucose, not on one reading. Vomiting, refusal to eat, marked weakness, trouble breathing, or collapse in a cat with known or suspected diabetes needs urgent care, because diabetic ketoacidosis is a serious complication.

An overactive thyroid, called hyperthyroidism, is common in middle aged and older cats and speeds the whole body up. Typical signs include weight loss despite a normal or increased appetite, restlessness, increased thirst and urination, and sometimes vomiting, diarrhea, or an unkempt coat. Kidney disease more often brings weight loss with a reduced appetite, increased thirst and urination, tiredness, and a poorer coat as it progresses. Intestinal disease, dental pain, and cancer are also on the list a veterinarian will consider. The practical point is the same in each case: unplanned weight loss is never something to simply feed through, because the cause, not the calorie count, is usually the real problem.

Sharper ribs, hips, or spine felt during stroking, a looser collar, or a narrower body seen from above can be early clues, especially in long haired cats. Any unplanned weight loss, rapid loss, visible muscle loss, or loss with vomiting, diarrhea, increased thirst, yellow gums, or trouble chewing needs a prompt examination.

Litter Box and Urinary Warning Signs

The litter box is a daily health report, and urinary signs are where timing matters most. Blood in a cat’s urine, called hematuria, may turn the urine pink, red, or brown. It can come from bladder inflammation, a bacterial urinary tract infection, bladder stones, a blockage, a kidney infection, a tumor, or a clotting problem. Bacterial infections are less common in otherwise healthy younger cats than many owners expect. Cornell identifies feline idiopathic cystitis, bladder inflammation with no confirmed infection or other cause found on testing, as the most common diagnosis in cats showing lower urinary tract signs, and notes that stress appears to be an important factor in its development. The AVMA makes the same point: bacterial infections are relatively uncommon in younger cats, and more common in cats older than 10 years, especially females, and in cats with kidney disease or diabetes.

Frequent trips to the litter box, straining, passing only small amounts of urine, crying during urination, accidents outside the litter box, and excessive licking of the genital area all deserve a same day call. Urinating outside the box in this context is a medical signal, not spite or bad behavior, and it should be reported rather than punished.

A cat that repeatedly strains but produces little or no urine needs emergency care at once. That pattern can mean a urethral obstruction, a blockage of the tube that carries urine out of the bladder. Cornell describes obstruction as an absolute emergency and warns that the time from complete obstruction to death may be less than 24 to 48 hours, because urine backs up, toxins build in the blood, and dangerous electrolyte imbalances develop. Male cats are at greater risk because their urethra is longer and narrower, and the AVMA notes obstruction is most often found in males between 1 and 10 years of age. Straining is often mistaken for constipation. Do not guess which it is, press on the abdomen, try to make the cat urinate, or give cranberry juice, apple cider vinegar, essential oils, or human medications while waiting for care.

Vomiting can accompany urinary problems, and it raises urgency, especially alongside straining, blood in the urine, or a painful abdomen. Vomiting alone does not prove a urinary infection, and a urinary infection alone does not explain every case of vomiting. Kidney infection, which is less common than lower urinary tract disease but can make a cat seriously ill, can bring fever, vomiting, poor appetite, and lethargy as well as urinary signs. Your veterinarian will need urine testing, and often blood tests or imaging, to separate these causes. A urine sample collected before any antibiotics begin, ideally directly from the bladder when the veterinarian judges it appropriate, gives the clearest result for bacterial culture.

Dehydration: What You Can and Cannot Check at Home

Signs linked to dehydration include dry or sticky gums, low energy, poor appetite, weakness, sunken eyes, and skin that stays tented after a gentle lift. Dry or tacky gums fit that picture, but gum texture alone cannot confirm dehydration, because dental disease, nausea, and breathing patterns can affect what you feel. Dehydration and weakness often appear together, and both suggest fluid loss affecting the whole body.

Dehydration happens when fluid losses exceed intake. Vomiting, diarrhea, reduced drinking, increased urination, fever, kidney disease, diabetes, hyperthyroidism, pain, and dental disease can all disrupt fluid balance. Cats that eat wet food take in much of their water from food, so a cat on wet food may drink less from a bowl without being dehydrated. Watch the whole pattern: eating less, drinking much more or much less than usual, vomiting or diarrhea, hiding more, and smaller or fewer urine clumps.

You can check gum moisture gently if your cat allows safe handling, and lift a fold of skin over the shoulder blades to watch how quickly it returns. Skin that settles slowly may suggest dehydration, but the test has limits. Older and underweight cats may have less elastic skin even with adequate hydration, while very young cats have highly elastic skin that can mask fluid loss, and a quick return does not rule out early fluid loss. Do not force water into the mouth. Offer fresh water in a clean, easy to reach bowl while you arrange care.

Owners sometimes search for the symptoms of a particular percentage of dehydration, such as 4 percent. A percentage figure is a clinical estimate made by a veterinarian from examination and laboratory findings, not something an owner can measure at home from a single sign. If several dehydration signs appear together, or the cat stops eating, drinking, or urinating normally, seek prompt care and let the veterinary team grade severity.

Breathing Changes and Coughing

Breathing is the sign to take most seriously of all. Cats at rest normally breathe quietly through the nose with little visible effort. A cat that breathes with its mouth open, pants, breathes rapidly at rest, or shows obvious abdominal effort with each breath needs emergency care. The same applies to gums or tongue that look blue, gray, or unusually pale, which can signal low oxygen. Do not delay travel to test other things first, and handle a cat in breathing distress as calmly as possible on the way.

Coughing sits one step down in urgency, but it is widely misunderstood. A cough is a reflex that clears irritants, mucus, or foreign material from the airways. Occasional coughing can be normal, but persistent coughing often points to an underlying problem. Many owners assume every coughing episode means a hairball, but the two look different. A hairball episode usually ends with a tubular wad of fur and some saliva. True coughing usually produces a dry hacking sound with little or nothing expelled, often with the cat crouching low with its neck extended.

Feline asthma is a common reason for persistent coughing. The Cornell Feline Health Center describes asthma as a disease of the lower airways, caused by an allergic reaction to inhaled allergens, in which inflammation, swelling, and constriction narrow the airways. Cornell lists the signs as difficulty breathing, wheezing, rapid breathing, coughing or hacking, open mouth breathing, or vomiting, ranging from acute crises to chronic low grade coughing. No single test definitively diagnoses asthma, so veterinarians combine history, imaging, and airway sampling, and rule out look alike conditions such as chronic bronchitis, lungworm, and pneumonia. Other causes of coughing include respiratory infections, heartworm, a foreign object such as a blade of grass, and irritants such as cigarette smoke, scented candles, sprays, and dusty litter.

Call your veterinarian promptly for coughing that lasts more than a few days, coughing with wheezing or labored breathing, or coughing alongside loss of appetite or lethargy. Reduce airborne irritants by using unscented cleaners, avoiding aerosols near resting spots, and choosing low dust, fragrance free litter. A short phone video of an episode, taken only if it does not delay care, can help the team tell coughing apart from retching.

Movement, Limping, and Pain Signs

Cats rarely cry out with everyday pain. More often, pain changes what a cat does: jumping less, avoiding stairs, sleeping in lower places, grooming less, or becoming irritable when touched in a place that was previously fine. AAHA senior pet guidance lists these mobility changes for older cats, including reluctance to jump, climb, or use the litter box normally, stiffness, limping, reduced grooming, and mood changes, as reasons to call the veterinarian.

A cat that is limping but still jumping and running can confuse owners, because playfulness does not rule out pain. A minor sprain, a small fracture, joint disease, a paw or pad injury, or a foreign object in the pad can all cause intermittent limping that comes and goes with movement. Stiffness after rest, reluctance to climb, decreased activity, reduced appetite, or pain when touched raise concern. Check the paw gently only if the cat tolerates it. If limping lasts more than a day, worsens, or comes with swelling, a wound, or a leg that cannot bear weight, call your veterinarian. Severe lameness or inability to move a leg is an emergency sign. Early examination matters for older cats too, because joint pain is treatable and is often mistaken for slowing down with age.

Behavior Change: Rule Out Medical Causes First

Behavior change shows up as a pattern, not a single sign. Hiding more, clinginess, increased vocalizing, avoiding the litter box, overgrooming with hair loss, loss of appetite, dilated pupils, and a tight, crouched posture can all occur with anxiety. Those signs overlap heavily with medical illness, so a veterinarian should rule out pain and disease first, with an examination and, when indicated, blood or urine tests. Treating a painful cat for anxiety alone delays the care that would actually help.

Once medical causes have been addressed, triggers are worth reviewing. Moves, new family members or pets, separation, loud noises, conflict with another cat, and changes in routine are common ones. The AVMA and Cornell both link stress to flare ups of feline idiopathic cystitis, and the AVMA describes environmental changes that increase a cat’s sense of control and safety, including safe resting places, separate resources for each cat in multi cat homes, clean and accessible litter boxes, daily play, and a predictable routine, as a core part of reducing those episodes. A safe retreat, high perches, scratching posts, and gradual exposure to feared situations help some anxious cats, and a veterinarian may discuss behavior support or medication for severe cases. What matters most is the order: examination first, behavior plan second.

Senior Cats: Changes That Are Not Just Old Age

Older cats change gradually, and gradual change is easy to excuse. The AAHA and AAFP life stage framework treats cats from 7 to 10 years as mature adults and cats over 10 years as seniors, and senior cats benefit from veterinary visits at least every six months, because several common conditions develop quietly at this age. “Slowing down” is a description, not a diagnosis.

Watch senior cats in particular for weight loss or muscle loss, increased thirst and urination, night vocalizing, reduced jumping, grooming less, sleeping much more, and any change in litter box habits. Night crying in a senior cat can accompany hearing or vision loss, cognitive changes, pain, an overactive thyroid, or high blood pressure, so it deserves an examination rather than an assumption. AAHA home monitoring guidance for senior pets repeats the same practical advice throughout: keep a habit of regular home checks, and tell your veterinarian right away when you notice a concerning change. A monthly weight, noted down, is one of the simplest checks, because a slow downward trend is easy to miss week to week but obvious on paper.

Dental disease deserves a special mention in seniors. Dropping food, chewing on one side, drooling, or guarding the head or mouth are listed by AAHA as reasons to call, and dental pain is a frequent hidden cause of reduced appetite in older cats.

What to Record Before You Call

A short, factual note makes triage faster and more accurate. Before you call, note the following:

What to record	Why it helps
When it started, and how fast it is changing	Separates emergencies from gradual problems
Last normal meal, and intake now	Appetite timing drives urgency
Drinking: more, less, or unchanged	Thirst change narrows the causes
Litter box: frequency, clump size, straining, blood	Urinary signs set the urgency
Vomiting or diarrhea: frequency and appearance	Frequency and blood change urgency
Breathing at rest, coughing, wheezing	Breathing effort is a first triage sign
Weight and any visible change	A trend beats a single reading
Medications, food changes, possible toxins or string	Exposure history changes first steps

A short video of unusual breathing or a coughing episode, taken only when it does not delay care, can help the team see what you are describing. If your regular practice is closed and the signs are in the emergency list below, go to an emergency clinic rather than waiting for morning.

When to Seek Emergency Care

Seek emergency veterinary care at once for difficulty breathing or open mouth breathing; collapse or inability to stand; a seizure; repeated vomiting or inability to keep water down; pale, white, blue, or gray gums; a swollen or painful abdomen; repeated straining with little or no urine; blood in the urine with vomiting, severe weakness, or collapse; severe lameness or inability to move a leg; or possible swallowing of string, medication, or a toxic plant. Poisoning, severe bleeding, and unconsciousness are also emergencies.

For other warning signs, call your veterinarian the same day and describe exactly what changed, when it started, and how quickly it is changing. Same day signs include blood in the urine without straining, a cat that has eaten little or nothing for about 24 hours, repeated trips to the litter box with urine still being passed, new limping, and several dehydration signs together. Signs that need a prompt routine appointment, rather than weeks of watchful waiting, include gradual weight loss, increased thirst, persistent coughing, grooming changes, and behavior change. When in doubt, call and let the practice triage.

Frequently Asked Questions

My cat is hiding and not eating. How long should I wait?

Do not wait beyond about 24 hours with little or no food in a healthy adult cat, and call sooner for a kitten or a cat with a chronic condition such as diabetes or kidney disease. An overweight cat that stops eating needs a prompt call too, because prolonged appetite loss can lead to hepatic lipidosis, a serious liver condition. Seek emergency care at once for breathing trouble, collapse, repeated vomiting, or straining without urine.

Does blood in my cat’s urine always mean infection?

No. Bladder inflammation without infection, stones, blockage, kidney disease, tumors, and clotting problems can all cause blood in the urine. Feline idiopathic cystitis, inflammation with no infection found, is the most common diagnosis in cats with lower urinary tract signs. Urine testing and examination are needed to find the cause, and antibiotics help only when a bacterial infection is present.

My cat is straining in the litter box. How do I know if it is an emergency?

Treat straining as an emergency whenever little or no urine is produced, the cat makes repeated trips, cries out, or becomes increasingly distressed. That pattern can mean a urethral blockage, which Cornell describes as an absolute emergency that can become life threatening within 24 to 48 hours, especially in male cats. Straining is often mistaken for constipation, and owners cannot reliably tell the two apart at home, so the safe action is an emergency call.

How can I tell dehydration from a simple dry mouth?

You cannot tell from one sign. Dry or tacky gums, weakness, sunken eyes, poor appetite, and skin that returns slowly after a gentle lift, taken together, suggest dehydration, but each sign has other explanations, and only a veterinary examination can grade severity. Several signs together should prompt care. Do not force water into the mouth while you arrange it.

Is my cat coughing or bringing up a hairball?

Coughing usually produces a dry hacking sound with little or nothing expelled, and the cat often crouches low with its neck extended. A hairball episode usually ends with a tubular wad of fur. Repeated coughing can reflect asthma, infection, or parasites, and no home test separates those causes. Frequent coughing, wheezing, or labored breathing needs veterinary assessment.

My senior cat is losing weight but still eating. Should I worry?

Yes, it deserves an examination. Weight loss with a good appetite is a classic pattern for an overactive thyroid and can also occur with diabetes, kidney disease, and intestinal disease. Blood and urine tests are usually needed to separate these causes. Do not simply feed more and wait.

When is limping an emergency?

Limping that lasts more than a day, worsens, or comes with swelling, a wound, or reduced appetite needs a prompt call. Severe lameness, a leg that cannot bear weight, or inability to move a leg is an emergency. A cat that limps intermittently but still runs and jumps can still be in pain, because cats hide discomfort and adjust their activity instead.

Sources & references

• Cornell Feline Health Center, Cornell University College of Veterinary Medicine. Feline Lower Urinary Tract Disease. Covers lower urinary tract signs, feline idiopathic cystitis, urinary stones, and urethral obstruction as an absolute emergency.
• Cornell Feline Health Center, Cornell University College of Veterinary Medicine. Hepatic Lipidosis. Covers fatty liver disease following a period of anorexia, its link to underlying conditions, and why prompt nutritional and veterinary care matters.
• Cornell Feline Health Center, Cornell University College of Veterinary Medicine. Feline Asthma: What You Need To Know. Covers asthma as a lower airway disease, its clinical signs, and why no single test confirms it.
• Cornell Feline Health Center, Cornell University College of Veterinary Medicine. Feline Diabetes. Covers the classic signs of diabetes in cats: increased appetite, weight loss, increased urination, and increased water consumption.
• American Veterinary Medical Association. Feline Lower Urinary Tract Disease (client brochure, 2024). Covers the causes and signs of FLUTD, bacterial infection frequency by age, urethral obstruction as an emergency requiring immediate care, and environmental modification for feline idiopathic cystitis.
• American Animal Hospital Association and American Association of Feline Practitioners. 2021 AAHA/AAFP Feline Life Stage Guidelines (AAHA Feline Life Stage Definitions page). Covers the feline life stage bands used in this article, including mature adult cats from 7 to 10 years and senior cats over 10 years, and veterinary visits at least every six months for senior cats.
• American Animal Hospital Association. Senior Pet: From Head to Toe, Home Monitoring Tips. Covers system by system signs to watch in senior pets, including breathing changes, urinary changes, appetite and weight change, mobility change, and not eating for more than 24 hours as a reason to seek immediate care.