How to Tell If Your Cat Is Sick: Signs You Shouldn't Ignore

Cats are experts at hiding when something is wrong.

That's why learning how to tell if your cat is sick isn't just about looking for obvious symptoms. A sick cat may not immediately appear seriously ill. Instead, the first clue may be a small change in behavior, appetite, grooming, litter box habits, or daily routine.

The most useful rule for cat owners is:

Know what is normal for your cat, then pay attention when that normal changes.

Common warning signs include eating less or more than usual, changes in thirst or urination, vomiting, diarrhea, weight loss, unusual tiredness, hiding, changes in grooming, breathing difficulties, and abnormal eye or nose discharge.

Some changes can wait for a veterinary appointment. Others—especially breathing problems, inability to urinate, severe weakness, or certain eye abnormalities—require prompt or emergency veterinary attention.

How Do I Know If My Cat Is Sick?

The easiest way to know if your cat may be sick is to look for persistent or unusual changes from their normal behavior.

Watch for changes in:

• Appetite

• Water consumption

• Energy level

• Social behavior

• Grooming

• Weight

• Breathing

• Urination and bowel movements

• Vomiting

• Eyes and nose

• Body posture

• Movement

One unusual behavior does not automatically mean your cat is sick.

But a sudden change—especially when several changes happen together—is worth taking seriously.

For example, a cat that normally greets you at the door but suddenly hides, stops eating, and spends most of the day sleeping is showing a meaningful change in behavior.

Why Is It So Hard to Tell When a Cat Is Sick?

Cats often hide signs of illness and pain.

From an evolutionary perspective, showing weakness could make an animal more vulnerable, so cats may not always display obvious symptoms when they are unwell.

As a result, a cat may be experiencing a health problem while appearing only slightly different from normal. VCA notes that an early sign may simply be that a cat becomes quieter or more withdrawn.

This is why knowing your cat's normal routine is so valuable.

If you know:

• How much your cat normally eats

• How often they drink

• How frequently they use the litter box

• How active they usually are

• How often they groom

• Where they normally sleep

• How they interact with you

then subtle changes become much easier to notice.

12 Signs Your Cat May Be Sick

1. Your Cat Suddenly Stops Eating

A reduced appetite is one of the most important changes to watch.

A cat may eat less because of something relatively minor, but loss of appetite can also accompany many different illnesses.

Pay particular attention if your cat:

• Refuses normally favorite foods

• Eats much less than usual

• Sniffs food but walks away

• Suddenly becomes unusually picky

• Stops eating altogether

VCA recommends immediate veterinary attention if a cat has not eaten properly for 24 hours.

Don't assume that a cat will simply "eat when it's hungry."

A significant or persistent change in appetite deserves attention.

2. Your Cat Is Drinking Much More or Less

Changes in thirst can also be an important clue.

You may notice that your cat:

• Visits the water bowl more frequently

• Drinks noticeably more water

• Suddenly seems uninterested in drinking

• Produces more urine than usual

• Produces less urine than usual

Increased thirst can occur with several medical conditions, while reduced drinking can contribute to dehydration.

Cornell lists excessive thirst and changes in urination among signs that can indicate illness.

If you use a water fountain or automatic water system, monitoring your cat's normal drinking pattern can make these changes easier to notice.

3. Your Cat Is Hiding More Than Usual

A cat that suddenly starts hiding may be telling you that something is wrong.

Hiding alone doesn't prove illness. Cats may hide because of:

• Stress

• New people

• Loud noises

• Changes in the home

• Other animals

• A desire for quiet

But if hiding is unusual for your cat and happens together with other changes, pay attention.

For example:

Hiding + reduced appetite + lethargy

is much more concerning than a cat simply taking a longer nap in a favorite hiding spot.

Hiding and withdrawal can be subtle early signs of illness.

4. Your Cat Seems Much More Tired

Cats sleep a lot, so it can be difficult to tell whether a cat is simply sleeping or is genuinely lethargic.

The key is to compare your cat with their normal behavior.

A concerning change may look like:

• Sleeping much more than usual

• Showing little interest in play

• Moving less

• Not responding normally to familiar activities

• Remaining in one position for unusually long periods

• Appearing weak or unwilling to move

A healthy cat may happily wake up for food or play.

A sick cat may show little interest even in activities they normally enjoy.

5. Your Cat's Grooming Habits Change

Grooming is another useful indicator of feline health.

A cat that suddenly stops grooming may develop a coat that looks:

• Greasy

• Matted

• Dull

• Untidy

• Flaky

Cornell notes that a dull or patchy coat can occur when a sick cat stops grooming normally.

But excessive grooming can also be a warning sign.

A cat may repeatedly lick or chew one area because of:

• Skin irritation

• Parasites

• Allergies

• Pain

• Stress

VCA notes that excessive grooming can have several possible causes, including skin problems, parasites, pain, and stress.

So both too little grooming and excessive grooming can be worth investigating.

6. Your Cat Loses or Gains Weight Unexpectedly

Unplanned weight change should not be ignored.

Slow weight loss can be difficult to see because it may happen gradually.

You might notice:

• Ribs becoming easier to feel

• A less muscular body

• A looser appearance around the abdomen

• A change in how your cat's body feels when you pick them up

Sudden weight loss can be particularly concerning.

Unexpected weight gain also deserves attention because excess body weight can affect overall health.

If your cat's weight is changing without a deliberate change to their diet or activity, discuss it with your veterinarian.

7. Your Cat Vomits Repeatedly

Occasional vomiting can happen in cats, but repeated vomiting is not something to dismiss automatically.

Cornell recommends veterinary evaluation for cats that vomit more frequently than once a week or that vomit alongside signs such as lethargy, weakness, reduced appetite, increased thirst, changes in urination, or diarrhea.

Pay particular attention to:

• Repeated vomiting

• Blood in vomit

• Vomiting combined with lethargy

• Vomiting and diarrhea together

• Vomiting with loss of appetite

• Vomiting with changes in drinking or urination

The appearance and frequency of vomiting can help a veterinarian determine what may be happening.

8. Your Cat Has Diarrhea or Changes in Stool

Changes in bowel movements can provide useful information about your cat's health.

Watch for:

• Loose or watery stool

• Very frequent bowel movements

• Blood

• Mucus

• Straining

• Sudden changes in stool consistency

• Repeated diarrhea

A brief episode can sometimes follow a dietary change or stressful event.

But persistent or recurring diarrhea—especially when accompanied by vomiting, lethargy, or poor appetite—should be evaluated by a veterinarian.

9. Your Cat Has Trouble Urinating

Litter box behavior is one of the most important things to monitor.

Warning signs include:

• Frequent trips to the litter box

• Straining to urinate

• Crying while urinating

• Producing only small amounts

• Blood in the urine

• Excessive licking around the genital area

• Urinating outside the litter box

• Producing little or no urine

Inability to urinate is an emergency.

VCA specifically identifies reduced urine production, small urine clumps, and lack of urination as reasons for immediate veterinary attention. Lack of urination can be life-threatening.

If your cat repeatedly enters the litter box but produces little or no urine, don't wait to see whether it improves.

10. Your Cat Is Breathing Differently

Changes in breathing deserve particular attention.

A cat with respiratory trouble may show:

• Rapid breathing

• Shallow breathing

• Noisy breathing

• Increased effort when breathing

• Coughing

• Wheezing

• Open-mouth breathing

• Neck extended while breathing

Open-mouth breathing or obvious difficulty breathing should be treated as an emergency.

Cats generally should not need to pant or breathe through an open mouth simply because they are resting.

Respiratory distress can have many possible causes, including airway, lung, or heart problems, so the underlying cause needs veterinary assessment.

11. Your Cat's Eyes or Nose Look Different

Changes around the eyes and nose can also indicate illness.

Look for:

• Eye discharge

• Nose discharge

• Squinting

• Redness

• Swelling

• Cloudiness

• Different-sized pupils

• A visible third eyelid

• Persistent sneezing

VCA notes that abnormal eye discharge, squinting, pupil changes, and an elevated third eyelid can be signs of a health problem.

Eye abnormalities deserve particular attention because some eye problems can threaten vision if treatment is delayed.

12. Your Cat's Posture or Movement Changes

Sometimes the first sign that a cat isn't feeling well is simply that they look different.

You may notice:

• A hunched posture

• Head held lower than usual

• Difficulty jumping

• Stiff movement

• Walking differently

• Reluctance to move

• A change in tail position

• Difficulty getting comfortable

These changes can indicate pain or illness, although there can be many possible explanations.

If your cat suddenly moves differently, especially after an injury, contact your veterinarian for advice.

Is My Cat Sick or Just Tired?

This is a common question.

Cats naturally sleep for many hours, so sleeping by itself is not necessarily a sign of illness.

The better question is:

Is my cat behaving differently from normal?

A healthy cat may sleep for hours and then suddenly become energetic when you open a treat bag.

A cat that is unwell may:

• Sleep more

• Avoid interaction

• Stop playing

• Eat less

• Move less

• Hide

• Respond less to familiar activities

If several of these happen together, it's more concerning than sleepiness alone.

Is Hiding Always a Sign That a Cat Is Sick?

No.

Hiding can be completely normal in certain situations.

For example, your cat may hide after:

• Moving to a new home

• Meeting a new person

• Hearing loud construction

• Introducing another pet

• Visiting the veterinarian

The important factor is change from your cat's normal behavior.

A naturally shy cat that occasionally hides is different from a normally social cat that suddenly disappears under the bed for most of the day.

When Should I Take My Cat to the Vet?

Contact your veterinarian if your cat develops a persistent, unexplained, or significant change in health or behavior.

You should be especially proactive when you notice:

• Loss of appetite

• Unexplained weight loss

• Repeated vomiting

• Persistent diarrhea

• Increased or decreased thirst

• Changes in urination

• Significant lethargy

• New or worsening pain

• Persistent coughing or sneezing

• Abnormal eye or nose discharge

The sooner a potential problem is evaluated, the easier it may be to identify what is happening.

When Is a Cat's Condition an Emergency?

Some symptoms should not wait for a routine appointment.

Seek urgent veterinary or emergency care for signs such as:

AAHA identifies difficulty breathing and persistent vomiting or diarrhea among important pet emergency signs. Cornell also advises immediate action for certain poisoning situations, and VCA identifies breathing difficulty and inability to urinate as urgent concerns.

If you believe your cat is experiencing an emergency, contact an emergency veterinary clinic rather than trying to diagnose the problem at home.

How Can You Monitor Your Cat's Health at Home?

You don't need to perform a medical examination every day.

Instead, develop a simple routine of observation.

Watch appetite

Know roughly how much your cat normally eats.

Monitor drinking

Notice whether water consumption suddenly changes.

Check the litter box

Look for changes in urine volume, frequency, or stool.

Observe behavior

Pay attention to play, social interaction, sleeping, and hiding.

Look at the coat

Notice whether grooming suddenly decreases or increases.

Monitor body condition

Regular weight checks can reveal gradual changes that are difficult to see.

Pay attention to breathing

Notice whether your cat's breathing appears comfortable and normal while resting.

These observations can also provide useful information for your veterinarian.

Can an Automatic Cat Feeder and Water Fountain Help You Notice Changes?

Smart pet-care devices can help owners establish a baseline for everyday routines.

For example, a portion-controlled feeder can help you keep track of how much food is offered, while a water fountain can make drinking behavior easier to observe.

Some connected pet-care devices may also provide records of feeding or drinking patterns.

These tools cannot diagnose illness, but changes in routine may give you another reason to pay closer attention.

For example:

Normal food intake → sudden decrease for several days

or:

Normal drinking → noticeably increased water consumption

can be useful observations to share with your veterinarian.

The device is a monitoring aid—not a replacement for veterinary care.

What Information Should I Give My Veterinarian?

If your cat is unwell, accurate observations can make the veterinary visit more useful.

Try to record:

• When the change started

• What changed

• How often it happens

• How much your cat is eating

• Changes in drinking

• Urination frequency

• Stool appearance

• Vomiting frequency

• Energy level

• Recent diet changes

• New medications or supplements

• Possible toxin exposure

• Recent injuries or stressful events

If possible, photos or videos of unusual behavior can also help your veterinarian understand what you observed at home.

Common Mistakes Cat Owners Make

Waiting for obvious symptoms

A cat doesn't need to look severely ill before a problem deserves attention.

Subtle behavioral changes can appear first.

Assuming vomiting is always a hairball

Not every episode of vomiting is caused by a hairball.

Repeated vomiting or vomiting combined with other symptoms should be evaluated.

Ignoring litter box changes

Changes in urination can be particularly important, and inability to urinate is an emergency.

Trying to diagnose the condition online

Symptoms such as poor appetite, lethargy, vomiting, and increased thirst can occur with many different conditions.

The same symptom can have very different causes.

A veterinarian needs to assess the cat as an individual.

Giving human medication

Never assume a medication that is safe for people is safe for cats.

If you think your cat has been exposed to a potentially toxic substance, contact a veterinarian or appropriate animal poison service promptly rather than trying to treat the problem yourself. Cornell specifically advises not inducing vomiting unless directed to do so.

A Simple Daily Cat Health Checklist

You can use this quick checklist to learn your cat's normal baseline:

Eating: Normal / Less / More

Drinking: Normal / Less / More

Energy: Normal / Lower / Higher

Behavior: Normal / Hiding / More withdrawn

Grooming: Normal / Less / Excessive

Urination: Normal / Changed

Stool: Normal / Changed

Vomiting: None / Occasional / Repeated

Breathing: Normal / Changed

Eyes & nose: Normal / Discharge or abnormality

Weight: Stable / Increasing / Decreasing

The purpose isn't to diagnose disease.

It's to notice changes early.

Frequently Asked Questions

How do I know if my cat is sick?

Look for changes from your cat's normal behavior, particularly appetite, drinking, energy, grooming, weight, litter box use, breathing, vomiting, and eye or nose appearance. Cats can hide illness, so subtle changes can be important.

How can you tell if a cat is sick?

You can look for persistent or sudden changes such as hiding, reduced appetite, lethargy, weight loss, vomiting, diarrhea, abnormal urination, increased thirst, breathing changes, or unusual eye and nose discharge.

How to tell if a cat is sick but still eating?

Eating normally does not guarantee that a cat is healthy. Watch for other changes such as reduced activity, hiding, altered grooming, weight loss, vomiting, diarrhea, increased thirst, or litter box changes.

Is hiding a sign of illness in cats?

It can be. Hiding is also a normal response to stress, so the key is whether the behavior is unusual for your individual cat and whether other symptoms are present.

How long can a cat go without eating?

A cat that has not eaten properly for 24 hours should receive prompt veterinary attention.

Is vomiting normal for cats?

Occasional vomiting can occur, but repeated vomiting or vomiting accompanied by lethargy, weakness, reduced appetite, diarrhea, or changes in thirst or urination warrants veterinary evaluation.

How do I know if my cat is dehydrated?

Reduced drinking, lethargy, and other signs can occur with dehydration, but home observations cannot reliably determine the severity or cause. If you suspect dehydration or your cat is not drinking normally, contact your veterinarian.

When should I take my cat to the vet?

Arrange veterinary care when your cat develops a persistent, significant, or unexplained change in behavior, appetite, weight, drinking, urination, bowel movements, grooming, or general condition. Seek urgent care for breathing difficulty, inability to urinate, collapse, severe weakness, or other emergency signs.

The Bottom Line

So, how to tell if your cat is sick?

Don't wait for your cat to look obviously ill.

Instead, learn your cat's normal routine and watch for meaningful changes in:

Eating → drinking → energy → grooming → weight → litter box → breathing → behavior

The most important clue is often not a single symptom but a change from what is normal for your cat.

And remember: symptoms alone cannot tell you exactly what is wrong. If your cat stops eating, has difficulty breathing, cannot urinate, develops significant eye abnormalities, or seems seriously unwell, seek veterinary attention promptly.

Your cat may not be able to tell you when something hurts.

Learning to recognize the small changes can help you notice when your cat needs help.