How to Tell If Your Cat Is Sick: 14 Subtle Warning Signs to Watch For

Cats are masters at hiding illness - an instinctive survival mechanism from their wild ancestors. By the time obvious symptoms appear, a cat may be seriously ill. Learning to recognize subtle signs of sickness is crucial for early intervention and successful treatment. Here's your guide to knowing when your cat needs veterinary care.

Cats Hide Illness

In the wild, sick animals are vulnerable to predators. Cats instinctively hide pain and illness until symptoms become severe. Subtle changes are often your only early warning.When in doubt, err on the side of caution and call your vet.

EMERGENCY SYMPTOMS - See Vet Immediately

Difficulty breathing, open-mouth breathing, or panting
Unconsciousness or unresponsiveness
Seizures
Suspected poisoning (lilies, antifreeze, human medications)
Trauma or severe bleeding
Straining to urinate with no urine (LIFE-THREATENING in male cats)
Sudden paralysis of hind legs
Not eating for 24+ hours (can lead to fatal liver disease)

14 Signs Your Cat Is Sick

1. Changes in Eating or Drinking

Decreased appetite:

Eating less or refusing food
Sniffing food but walking away
Only eating treats, avoiding regular food
CRITICAL: Cats who don't eat for 24-48 hours risk hepatic lipidosis (fatty liver disease), which can be fatal

Increased drinking (polydipsia):

May indicate diabetes, kidney disease, hyperthyroidism
Watch for frequent trips to water bowl
In Mauritius heat, some increased drinking is normal, but excessive is concerning

2. Hiding or Withdrawal

Why it matters:

Often the FIRST and most subtle sign of illness
Seeking quiet, dark places (under bed, in closets, behind furniture)
Avoiding family members they usually seek out
Not greeting you at the door or coming for meals

Action: Any change in social behavior warrants monitoring. If accompanied by other symptoms or lasts more than 24 hours, call vet.

3. Litter Box Changes

Urination changes:

Straining to urinate: EMERGENCY in male cats (urinary blockage can be fatal within 24-48 hours)
Frequent small amounts: May indicate urinary tract infection or crystals
Blood in urine: Infection, crystals, or more serious issue
Urinating outside litter box: May be medical (UTI, kidney disease) or behavioral
Increased urination: Diabetes, kidney disease, hyperthyroidism

Defecation changes:

Diarrhea (loose, watery stools)
Constipation (straining, hard stools, no stool for 2+ days)
Blood in stool
Black, tarry stools (internal bleeding)

4. Vomiting

Normal vs. concerning:

Occasional hairballs: 1-2x per month can be normal (see Hairball Guide)
Concerning: Frequent vomiting (multiple times per day or week), vomiting food, blood in vomit, projectile vomiting, accompanied by lethargy
May indicate: Kidney disease, hyperthyroidism, GI disease, foreign object, poisoning

5. Weight Changes

Weight loss:

Especially concerning if eating normally or eating MORE (hyperthyroidism, diabetes)
Feel along spine and ribs - bones more prominent
Muscle wasting, especially in hind legs
Even 0.5 kg matters in cats - monitor closely

Weight gain:

Can lead to diabetes, arthritis, liver disease
Sudden gain may indicate fluid retention

6. Decreased Grooming

Cats are meticulous groomers. Poor grooming indicates illness:

Unkempt coat: Dull, greasy, matted fur
Not cleaning after litter box: Soiled rear end
Why it happens: Arthritis (hurts to groom), dental pain, obesity (can't reach), illness (too weak)

Over-grooming: Excessive licking creating bald patches may indicate allergies, parasites, stress, or pain.

7. Lethargy or Decreased Activity

Signs:

Sleeping more than usual (cats sleep 12-16 hours normally, so this means sleeping even MORE)
Not interested in play or toys
Not jumping to favorite high places
Moving slowly or stiffly
Reluctance to climb stairs

Note: In Mauritius heat, some reduced activity during hot hours is normal. Concerning if cat is lethargic even in cool morning/evening hours.

8. Breathing Changes

Normal cat breathing: 20-30 breaths per minute at rest, quiet, through nose

EMERGENCY breathing signs:

Open-mouth breathing or panting: NEVER normal in cats (except briefly after intense play or in extreme heat)
Rapid breathing: More than 40 breaths per minute at rest
Labored breathing: Visible effort, chest and belly moving excessively
Wheezing or coughing: Asthma, heart disease, respiratory infection

9. Vocalization Changes

Increased vocalization:

Yowling, crying, meowing more than normal
Especially at night (may indicate cognitive dysfunction in senior cats, or hyperthyroidism)
Crying when using litter box (pain during urination/defecation)
Yowling when touched (pain)

Decreased vocalization:

Normally vocal cat becomes quiet
May indicate weakness, depression, pain

10. Eye or Nose Discharge

Eyes:

Discharge (clear, yellow, green, crusty)
Redness or bloodshot eyes
Squinting, keeping eyes closed
Third eyelid visible (nictitating membrane showing)
Cloudiness or color change

Nose:

Discharge (especially colored or thick)
Sneezing
Congestion, noisy breathing

11. Behavior Changes

Watch for:

Aggression: Uncharacteristic hissing, swatting, biting (often indicates pain)
Restlessness: Pacing, can't settle, frequent position changes
Clinginess: Normally independent cat becomes clingy
Confusion: Getting lost, staring at walls, not recognizing family

12. Bad Breath and Dental Issues

Signs:

Extremely foul breath (beyond normal cat breath)
Drooling (not normal in cats)
Difficulty eating or dropping food
Pawing at mouth
Red, swollen, or bleeding gums
Visible tartar or broken teeth

Why it matters: Dental disease affects 70% of cats by age 3 and can lead to systemic infections affecting heart, kidneys, and liver.

13. Third Eyelid Showing

The nictitating membrane (third eyelid, located at inner corner of eye):

Normal: Not visible, or briefly visible when cat wakes
Concerning: Persistently visible, covering part of eye
May indicate: Illness, dehydration, pain, eye injury, neurological issues

14. Drooling

Occasional: Brief drooling during happy purring (some cats)

Concerning:

Persistent or excessive drooling
New behavior (cat never drooled before)
May indicate: Dental disease, oral injury, nausea, poisoning, foreign object in mouth

When to Call the Vet

Call Immediately (Emergency)

Difficulty breathing, open-mouth breathing, or panting
Straining to urinate with no urine (especially male cats)
Unconscious or unresponsive
Seizures
Sudden paralysis (especially hind legs)
Severe bleeding or trauma
Suspected poisoning (lilies, antifreeze, human medications, essential oils)
Pale or blue gums
Collapse or extreme weakness

Call Same Day

Not eating for 24+ hours
Multiple episodes of vomiting or diarrhea
Blood in urine or stool
Hiding and showing other symptoms
Frequent urination or urinating outside litter box
Labored breathing or persistent coughing
Eye injury or sudden vision changes
Limping or difficulty moving
Excessive vocalization with signs of distress

Schedule Appointment Soon (Within 1-2 Days)

Gradual decrease in appetite
Weight loss or gain
Increased drinking and urination
Poor grooming or unkempt coat
Decreased activity level
Mild but persistent vomiting (1-2x per week)
Behavior changes that persist
Dental issues or bad breath
Any new lumps or bumps

Common Cat Illnesses in Mauritius

Chronic Kidney Disease

Very common in cats, especially seniors
Signs: Increased drinking/urination, weight loss, vomiting, poor appetite
Action: Early detection through bloodwork allows management

Hyperthyroidism

Common in cats 10+ years old
Signs: Weight loss despite increased appetite, hyperactivity, vomiting, increased drinking
Action: Treatable with medication, radioactive iodine, or surgery

Diabetes

Increasing in cats due to obesity
Signs: Increased drinking/urination, increased appetite but weight loss
Action: Manageable with insulin and diet

Urinary Tract Issues

Infections, crystals, blockages
Signs: Straining, frequent trips to litter box, blood in urine, urinating outside box
Action: Male cat blockage is EMERGENCY - fatal within 24-48 hours if untreated

Parasites (Mauritius Tropical Climate)

Year-round flea, tick, worm risk in tropical environment
Signs: Scratching, hair loss, weight loss, vomiting, diarrhea, visible worms in stool
Action: Year-round prevention essential (see Flea and Tick Guide)

Home Monitoring

Taking Your Cat's Temperature

Normal: 37.5-39.2°C (99.5-102.5°F)
Method: Rectal thermometer (difficult without training - best done by vet)
Fever: Above 39.5°C (103°F)

Checking Hydration

Skin tent test: Gently pinch skin on scruff - should snap back immediately
Gum check: Should be moist, not dry or sticky
Sunken eyes: Sign of dehydration

Gum Color

Normal: Pink and moist
Pale/white: Anemia, shock
Bright red: Overheating, inflammation
Blue/purple: EMERGENCY - oxygen deprivation
Yellow: Liver disease

Preventive Care in Mauritius

Regular Vet Visits

Annual exams for adult cats
Twice yearly for cats 7+ years old
Bloodwork to catch kidney disease, hyperthyroidism, diabetes early

Parasite Prevention

Year-round flea, tick, worm prevention (essential in tropical Mauritius)
Monthly treatments recommended
Indoor cats still need prevention (fleas can enter on humans, other pets)

Heat Management

Provide cool areas (AC, fans, tile floors)
Multiple water sources
Monitor for heat stress (see Cooling Guide)

Nutrition

High-quality, appropriate-for-life-stage cat food
Maintain healthy weight (obesity shortens lifespan)
Fresh water always available

Finding a Vet in Mauritius

Establish vet relationship before emergencies. Save emergency numbers in your phone.

Key Takeaways

Cats instinctively hide illness - subtle changes are often only early warning
Hiding or withdrawal is often FIRST sign something is wrong
Not eating for 24+ hours is EMERGENCY (risk of fatal liver disease)
Male cats straining to urinate = LIFE-THREATENING emergency
Open-mouth breathing/panting is NEVER normal in cats
Changes in litter box habits require prompt vet visit
Weight loss even while eating normally needs investigation
Senior cats (7+) need twice-yearly vet visits for early disease detection
Know your cat's baseline behavior to spot changes
When in doubt, call vet - better safe than sorry with cats