How to Tell If Your Cat Is Sick

Name: How to Tell If Your Cat Is Sick
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

You know your cat better than anyone. That is why the first sign of illness is often a small change you notice before anything looks dramatic. Learning how to tell if my cat is sick starts with watching for shifts in eating, drinking, grooming, activity, and litter box habits, because cats hide discomfort well.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Any sudden change in behavior, appetite, thirst, or litter box use deserves a call to your vet, because cats rarely show obvious pain until illness is advanced [1].
Common sick cat symptoms include hiding, less activity or more activity than usual, not eating, vomiting, diarrhea, weight loss, bad breath, and changes in urination [1].
Senior cats over 8 to 9 years old should see a vet twice a year or more, since older cats get sick more often and early detection matters [1].
Kittens and cats with rapid breathing, straining to urinate, collapse, or repeated vomiting need emergency care the same day.
Never give human medications, including pain relievers, without veterinary direction, because many are toxic to cats.

What Early Illness Looks Like in Cats

Cats are built to mask weakness. A sick cat may still jump on the counter, purr, and greet you, even when something is wrong. That is why subtle changes matter more than dramatic ones.

Start with the basics you see every day:

Appetite. A cat that skips one meal may be fine. A cat that refuses food for 24 hours, or eats noticeably less for two or three days, needs a vet visit.
Water intake. Drinking more than usual can point to kidney disease, diabetes, or hyperthyroidism. Drinking less can lead to dehydration fast.
Litter box habits. Watch for straining, small urine spots, accidents outside the box, or stool changes. These are common signs of cat being sick.
Activity level. Some sick cats sleep more and hide. Others pace, vocalize, or seem restless. Both are worth noting [1].
Grooming. A dull, greasy, or matted coat often means a cat has stopped grooming because it feels unwell.
Weight. You may not notice gradual loss. Weigh your cat monthly on a baby scale if you can.
Breathing. Normal resting breathing in a cat is quiet and easy. Labored breathing, open-mouth breathing, or a resting rate above about 40 breaths per minute is an emergency.

Senior cats are a special case. In one study of 129 cats aged 12 and older whose owners described them as healthy, every single cat had an abnormality on physical examination, most commonly dental disease [2]. Diagnostic testing also found high rates of previously unrecognized disease, including chronic kidney disease in about 61 percent of tested cats and hypertension in many others [2]. Your cat can look fine and still have a problem brewing.

Signs of Cat Getting Sick: A Body System Checklist

Eyes, Nose, and Mouth

Cloudy, red, or squinting eyes
Discharge from the eyes or nose
Sneezing that lasts more than a few days
Drooling or dropping food while eating
Bad breath, which can signal dental disease or other illness. See Cat Bad Breath: When Is It a Sign of Illness?

Upper respiratory infections are common in cats. One study found a significant link between oculonasal discharge and prior exposure to feline herpesvirus type 1, a major cause of upper respiratory and eye disease [3]. That means goopy eyes and a runny nose are not something to shrug off.

Digestive Signs

Vomiting, especially repeated vomiting or vomiting after every meal
Diarrhea lasting more than a day, or any diarrhea in a kitten
Constipation or straining to pass stool
Abdominal pain, which may look like a hunched posture or flinching when picked up

For more on loose stool, read Cat Diarrhea: How to Tell If It's Serious and What to Do.

Urinary Signs

Peeing outside the litter box
Crying out while urinating
Frequent trips to the box with little or no urine produced
Blood in the urine
Licking the genital area more than usual

A male cat straining to urinate is a life-threatening emergency. A blocked urethra can be fatal within a day. Learn the full list in What Are The Signs That My Cat Has A Urinary Tract Infection.

Respiratory Signs

Coughing that lasts more than a few days
Wheezing or noisy breathing
Rapid or shallow breathing at rest
Exercise intolerance

Chronic cough has many causes, including infections, inflammation, and airway disease [4]. If your cat makes a hacking sound, it can be hard to tell coughing from dry heaving. This guide helps: Is My Cat Dry Heaving Or Coughing.

Neurologic and Whole-Body Signs

Head tilt, circling, or loss of balance
Seizures or tremors
Sudden blindness
Weakness in the back legs
Fever, which you cannot measure reliably at home without a rectal thermometer
Jaundice, a yellow tint to the gums, skin, or whites of the eyes

How to Tell If My Kitten Is Sick

Kittens get sick faster than adult cats. Their small bodies lose fluids and energy quickly, so a problem that would be minor in an adult can become serious in hours.

Watch for these signs in kittens:

Not nursing or not eating solid food
Crying constantly or being unusually quiet
Cold body temperature or feeling cool to the touch
Diarrhea or vomiting of any amount
A distended belly
Discharge from the eyes or nose
Lethargy, meaning the kitten does not resist being handled

Kittens also need their vaccine series on schedule. Vaccination is essential for all cats, whether they stay indoors or go outside, and your vet will choose vaccines based on your cat's lifestyle and where you live [1]. If you have a kitten, do not delay the first vet visit.

Main Causes of Illness in Cats

Cause	Typical clues	How urgent
Dental disease	Bad breath, drooling, dropping food, pawing at the mouth	Routine visit, but sooner if not eating
Chronic kidney disease	Increased thirst and urination, weight loss, poor appetite	Same-week visit, sooner if vomiting
Hypertension	Often silent, sometimes sudden blindness or seizures	Same-day or next-day visit
Urinary blockage	Straining, crying, no urine, hiding	Emergency now
Upper respiratory infection	Sneezing, eye and nose discharge, fever	Same-day to next-day visit
Chronic cough or lung disease	Ongoing cough, fast breathing, weight loss	Same-week visit, emergency if breathing is hard
Viral infections such as FIV	Weight loss, poor coat, recurring infections	Same-week visit with testing
Parasites such as Toxoplasma	Variable signs, often linked to other illness	Same-week visit with testing

Some infections overlap. In one study of domestic cats, those testing positive for Toxoplasma gondii or feline immunodeficiency virus showed clinical signs significantly more often than cats that tested negative [5]. Feline immunodeficiency virus suppresses the immune system and can let other infections take hold [5]. This is one reason your vet may recommend blood tests when your cat has vague, ongoing symptoms.

Chronic infections can also hide for a long time. In one report, two cats with long-standing cough, lethargy, and weight loss turned out to have a bacterial lung infection that required months of triple antimicrobial therapy [6]. Both cats recovered fully, but only after a proper diagnosis and a long treatment course [6]. The lesson is simple: a cough that will not quit deserves a workup.

Red Flags That Mean Emergency

Call an emergency clinic right away if you see any of these:

Open-mouth breathing, or breathing that looks like hard work
Straining to urinate with little or no urine produced
Collapse, seizure, or unresponsiveness
Repeated vomiting or vomiting blood
A distended, painful abdomen
Bleeding that will not stop
Suspected poisoning, such as eating a toxic plant or human medication
A kitten that is limp, cold, or not eating

For poisoning, contact a pet poison hotline or your vet immediately. Do not wait for symptoms to appear.

What You Can Safely Do at Home While Waiting

You cannot treat most cat illnesses at home, but you can keep your cat stable and comfortable until the appointment.

Offer water in several places. Use shallow bowls and keep them clean. If your cat seems dehydrated, read Cat Dehydration Symptoms: How to Tell and What to Do.
Warm bland food. Slightly warmed wet food often smells more appealing to a cat with a poor appetite.
Keep a quiet room. Set up a bed, litter box, food, and water in one low-traffic space so your cat does not have to travel far.
Track everything. Write down what your cat eats, drinks, pees, and poops, plus the times. This helps your vet a lot.
Do not give human medications. Never give acetaminophen, ibuprofen, aspirin, or any other human drug to a cat unless your vet prescribes it. Many are toxic.
Do not force food or water. This can cause choking or aspiration.
Separate your cat from other pets. This lowers stress and prevents spread if the problem is contagious.

If your cat is vomiting, withhold food only if your vet tells you to. Otherwise, offer small amounts of the usual diet.

What Your Veterinarian Will Check and Test

Your vet will start with a full history. Bring your notes. Then expect a nose-to-tail physical exam, including:

Weight and body condition score
Temperature, heart rate, and breathing rate
Dental exam
Abdominal palpation
Eye, ear, and skin check
Listening to the heart and lungs

Depending on what they find, your vet may recommend:

Blood work, including a complete blood count and chemistry panel to check organs, blood sugar, and proteins
Urinalysis, which checks for infection, crystals, and kidney function
Blood pressure measurement, since hypertension is common in older cats and often silent [2]
Thyroid testing, especially in cats over 8
Infectious disease testing, such as for feline immunodeficiency virus or Toxoplasma when signs fit [5]
Imaging, including X-rays or ultrasound, for coughing, breathing trouble, or abdominal signs [4]
Airway sampling, such as a bronchoalveolar lavage, when a lung problem is suspected [6]

Treatment depends on the diagnosis. Some conditions need antibiotics or other antimicrobials, some need anti-inflammatories or bronchodilators, and some need long-term management [4]. When a cause cannot be cured, treatment can still control signs and improve quality of life [4]. Doses for any medication are calculated by your veterinarian based on your cat's weight and health. Never guess a dose.

Prevention and Monitoring

Vet visits. Healthy adult cats need at least one exam a year. Senior cats over 8 to 9 years old should go twice a year or more, and your vet may suggest regular blood tests to catch chronic illness early [1].
Vaccines. Keep your cat current on vaccines based on your vet's advice for your region and lifestyle [1].
Weight checks. Weigh your cat monthly. A loss of even a few ounces matters.
Litter box log. Note clumps and stool daily. Changes show up here first.
Dental care. Dental disease was the most common finding in senior cats in one study [2]. Ask your vet about dental cleanings.
Parasite control. Keep flea, tick, and worm prevention current.
Indoor safety. Keep toxic plants, medications, and string-like objects out of reach.

If your cat seems unwell, take it to the vet right away [1]. Trust your gut. You are the best observer your cat has.

Limitations and When to Contact a Veterinarian

This article gives general guidance only. Every cat is an individual, and only a veterinarian who examines your cat can diagnose and treat illness.

Use these timing rules:

Emergency now. Open-mouth breathing, straining to urinate, collapse, seizure, uncontrolled bleeding, suspected poisoning, or a nonresponsive kitten.
Same day. Repeated vomiting, bloody diarrhea, a cat that will not eat for 24 hours, sudden weakness, or a sudden change in behavior.
Routine visit within a few days. Mild sneezing, a single episode of vomiting, mild itching, or a small change in appetite that lasts more than a day.
Routine wellness visit. Any cat over 8 to 9 years old, even if it seems completely healthy [1][2].

When in doubt, call your vet's office and describe what you see. Most clinics would rather answer a quick question than treat a problem that got worse overnight.

Frequently Asked Questions

How can I tell if my cat is in pain?

Cats in pain often hide, stop grooming, eat less, and sit in a hunched position. They may also become irritable when touched or avoid jumping. Because cats mask pain well, any of these changes should prompt a vet visit.

Why is my cat hiding more than usual?

Hiding is one of the most common early signs of illness in cats. A cat that suddenly spends time under the bed or in a closet may be nauseated, painful, or feverish. If the behavior lasts more than a day, call your vet.

Can a cat be sick and still eat normally?

Yes. Some illnesses, especially early kidney disease, dental problems, and high blood pressure, can be present while your cat still eats. That is why regular exams and lab work matter, particularly for cats over 8 years old.

How long can a sick cat go without eating?

A cat that has not eaten for 24 hours should be seen by a vet. Cats that stop eating for longer can develop serious liver problems. Do not wait several days to see if the appetite returns on its own.

Should I wait to see if my cat gets better on its own?

For very mild, brief signs, a day of watching at home is reasonable. For anything that lasts more than 24 hours, gets worse, or involves breathing, urination, or repeated vomiting, do not wait. Call your vet.

References

Routine Health Care of Cats - Cat Owners. Merck Veterinary Manual.
Clinically important abnormalities are common in senior cats perceived to be healthy by owners. Journal of the American Veterinary Medical Association, 2026.
Tracing feline herpesvirus-1 exposure in domestic cats from Namibia: associations with neutralising antibodies, vaccination, clinical signs, and retroviral status. Veterinary research communications, 2026.
The Approach to Chronic Cough in Dogs and Cats. The Veterinary clinics of North America. Small animal practice, 2026.
Seroprevalence of Toxoplasma gondii and Feline Immunodeficiency Virus in Domestic Cats and Their Associations with Clinical Signs. Acta parasitologica, 2026.
Successful Treatment of Mycobacterium caprae Infection in Two UK Cats. Veterinary medicine and science, 2026.