Cats are masters at hiding pain and illness. Unlike dogs, they rarely show obvious signs when something is wrong. This instinct comes from their wild ancestors, where appearing weak made them vulnerable to predators.
Unfortunately, this natural behavior means many cat owners don't realize their pet is sick until the condition has become serious.
Learning the subtle signs your cat is sick can help you detect health problems early, seek timely veterinary care, and potentially save your cat's life. Even small behavioral or physical changes deserve attention because they may indicate an underlying medical issue.
In this guide, you'll learn the ten most common warning signs that your cat may be sick—even if they still seem happy, playful, or affectionate.
Why Cats Hide Illness So Well
Before discussing the symptoms, it's important to understand why cats often appear normal despite being unwell.
Cats evolved as both predators and prey. Showing weakness in the wild could attract larger predators or reduce their ability to hunt. As a result, domestic cats instinctively mask discomfort until they can no longer compensate.
This means by the time obvious symptoms appear, the illness may already be advanced.
That's why paying attention to daily habits is one of the most effective ways to protect your cat's health.
1. Changes in Appetite
One of the earliest signs your cat is sick is eating differently.
Some cats suddenly stop eating, while others begin eating significantly more than usual.
Loss of Appetite
A cat refusing food for more than 24 hours should always be taken seriously.
Possible causes include:
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Dental disease
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Kidney disease
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Liver disease
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Fever
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Infections
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Digestive disorders
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Cancer
Cats that stop eating completely are also at risk of developing hepatic lipidosis (fatty liver disease), which can become life-threatening.
Increased Appetite
Eating much more than usual can also indicate illness.
Common causes include:
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Hyperthyroidism
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Diabetes
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Intestinal parasites
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Poor nutrient absorption
2. Drinking More or Less Water
Changes in water intake often indicate internal disease.
Many owners don't notice because cats naturally drink small amounts.
Watch for:
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Frequently visiting the water bowl
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Empty bowls much faster
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Drinking from faucets or sinks
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Reduced water consumption
Excessive thirst commonly occurs with:
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Diabetes
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Kidney disease
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Hyperthyroidism
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Urinary problems
Reduced drinking may accompany dehydration, nausea, or serious illness.
3. Changes in Litter Box Habits
The litter box provides valuable clues about your cat's health.
Monitor:
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Frequency of urination
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Stool consistency
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Urine volume
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Straining
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Blood
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Accidents outside the litter box
Urinating More Frequently
May indicate:
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Diabetes
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Kidney disease
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Urinary tract infection
Straining to Urinate
This is an emergency, especially for male cats.
Possible causes:
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Urinary blockage
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Bladder stones
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Inflammation
Without treatment, urinary blockage can become fatal within hours.
Diarrhea or Constipation
Digestive changes may result from:
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Parasites
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Food intolerance
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Infection
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Inflammatory bowel disease
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Stress
4. Weight Loss Without Diet Changes
Unexpected weight loss is one of the most overlooked signs your cat is sick.
Because cats have thick fur, gradual weight loss often goes unnoticed.
Possible causes include:
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Kidney disease
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Hyperthyroidism
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Diabetes
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Cancer
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Digestive disorders
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Dental pain
Weigh your cat monthly if possible.
Even losing a small percentage of body weight can indicate disease.
5. Changes in Grooming Habits
Healthy cats spend several hours each day grooming themselves.
When grooming habits change, illness may be developing.
Poor Grooming
A greasy, matted, or unkempt coat can indicate:
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Arthritis
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Obesity
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Dental pain
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Kidney disease
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Depression
Older cats often struggle to groom because movement becomes painful.
Excessive Grooming
Constant licking may result from:
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Allergies
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Fleas
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Anxiety
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Skin infections
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Pain
Some cats lick themselves so much that bald patches develop.
6. Sleeping More Than Usual
Cats naturally sleep 12 to 16 hours daily.
However, sudden increases in sleeping or decreased activity deserve attention.
Ask yourself:
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Does your cat ignore favorite toys?
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Do they stop greeting family members?
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Are they hiding more often?
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Do they avoid climbing stairs?
Lethargy may indicate:
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Infection
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Fever
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Pain
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Heart disease
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Anemia
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Chronic illness
7. Hiding or Personality Changes
A friendly cat suddenly hiding under furniture may be trying to avoid interaction because they're uncomfortable.
Behavior changes often occur before physical symptoms appear.
Examples include:
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Becoming unusually quiet
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Increased aggression
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Irritability
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Avoiding touch
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Clinginess
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Restlessness
Cats in pain frequently become less social.
Conversely, some become unusually affectionate because they seek comfort.
8. Vomiting More Than Occasionally
Many owners assume vomiting is normal in cats.
Occasional hairballs happen.
Frequent vomiting does not.
Consult your veterinarian if your cat:
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Vomits multiple times weekly
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Vomits after every meal
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Produces blood
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Loses weight
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Appears lethargic
Possible causes include:
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Hairballs
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Gastrointestinal disease
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Kidney disease
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Poisoning
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Foreign body obstruction
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Food allergies
Persistent vomiting always warrants investigation.
9. Difficulty Breathing or Persistent Coughing
Breathing problems should never be ignored.
Signs include:
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Rapid breathing
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Open-mouth breathing
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Wheezing
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Labored breathing
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Blue gums
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Persistent coughing
Possible causes include:
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Asthma
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Heart disease
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Lung infection
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Pleural effusion
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Trauma
Difficulty breathing is a veterinary emergency.
Seek immediate medical attention.
10. Changes in Eyes, Nose, Mouth, or Ears
Your cat's face often provides visible clues about health.
Watch for:
Eyes
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Redness
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Cloudiness
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Excessive tearing
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Squinting
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Unequal pupils
These may indicate:
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Eye infection
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Corneal ulcers
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Glaucoma
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High blood pressure
Nose
Persistent nasal discharge can result from:
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Upper respiratory infections
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Allergies
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Dental disease
Mouth
Warning signs include:
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Bad breath
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Drooling
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Difficulty chewing
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Bleeding gums
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Loose teeth
Dental disease affects many adult cats and can lead to infections throughout the body.
Ears
Look for:
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Scratching
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Head shaking
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Wax buildup
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Bad odor
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Discharge
These symptoms commonly indicate:
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Ear mites
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Bacterial infection
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Yeast infection
Additional Warning Signs That Should Never Be Ignored
Some symptoms require immediate veterinary care regardless of your cat's overall appearance.
These include:
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Collapse
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Seizures
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Severe bleeding
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Difficulty breathing
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Unable to urinate
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Repeated vomiting
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Blood in urine
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Blood in stool
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Sudden blindness
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Swollen abdomen
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Extreme weakness
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Poison ingestion
Prompt treatment can dramatically improve outcomes.
How to Monitor Your Cat's Health at Home
Because cats hide illness, routine observation is your best defense.
Check Daily
Pay attention to:
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Appetite
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Water intake
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Energy level
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Grooming
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Breathing
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Bathroom habits
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Behavior
Small daily observations help identify gradual changes.
Perform Monthly Checks
Examine your cat for:
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Weight changes
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Skin lumps
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Coat condition
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Teeth and gums
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Eyes
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Ears
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Nails
Early detection often makes treatment easier and more successful.
When Should You Visit the Veterinarian?
Schedule an appointment if symptoms last longer than 24 to 48 hours or continue worsening.
Seek emergency care immediately if your cat:
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Cannot urinate
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Has trouble breathing
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Stops eating completely
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Has repeated seizures
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Is extremely lethargic
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Experiences trauma
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Has severe vomiting or diarrhea
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Appears unable to stand
Trust your instincts.
If something feels different about your cat, it's worth getting them examined.
Tips to Keep Your Cat Healthy
While not every illness is preventable, good preventive care significantly lowers health risks.
Healthy habits include:
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Feeding a balanced, high-quality diet
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Providing clean, fresh water daily
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Keeping litter boxes clean
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Maintaining a healthy body weight
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Scheduling regular veterinary wellness exams
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Staying current on vaccinations
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Using parasite prevention as recommended
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Encouraging daily play and exercise
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Brushing your cat regularly
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Reducing stress with a stable routine
Prevention is always easier—and often less expensive—than treating advanced disease.
Final Thoughts
Recognizing the early signs your cat is sick is one of the most important responsibilities of being a cat owner. Because cats instinctively hide pain and discomfort, subtle changes in their daily routine are often the first clues that something isn't right.
By paying close attention to your cat's appetite, grooming, litter box habits, activity level, and behavior, you can catch potential health problems sooner and seek veterinary care before they become more serious.
Remember, you know your cat better than anyone. If they seem "off" in any way—even if they otherwise appear fine—it's always safer to consult your veterinarian. Early diagnosis and treatment can make a significant difference in your cat's comfort, recovery, and long-term health.
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