How to Know if My Cat is Sick? 12 Signs

How to Know if My Cat is Sick? 12 Signs

Cats are experts at hiding their pain. It's a survival instinct inherited from their wild ancestors: an animal that shows signs of weakness becomes prey. What makes cats warriors in the wild makes them particularly hard to "read" as pets.

When a cat shows visible signs of illness, it often means the problem is already advanced. That's why it's essential to know the subtle signals that indicate discomfort. Here are the 12 signs that should alert you.

1. Change in Appetite

A cat that suddenly eats much less, or much more, than usual deserves special attention.

Loss of Appetite

A cat that hasn’t eaten for more than 24 hours should be taken seriously. Unlike dogs, cats can't fast for long without risk. A fast of 48 to 72 hours can lead to hepatic lipidosis (fatty liver disease), a potentially fatal condition.

Possible causes of loss of appetite are numerous: dental problems (pain while chewing), nausea, infections, stress, abdominal pain, kidney failure.

Increased Appetite

A cat that eats much more without gaining weight (or while losing weight) may suffer from hyperthyroidism (common in cats over 8 years old) or diabetes. Both are treatable but require a vet diagnosis.

2. Excessive Thirst (Polydipsia)

If your cat suddenly drinks much more than usual, it's a red flag. The most common causes are:

• Kidney failure: the leading cause of death in older cats. The kidneys no longer filter properly, so the cat drinks to compensate.
• Diabetes: sugar in the blood "pulls" water, so the cat compensates by drinking more.
• Hyperthyroidism: speeds up metabolism, increases thirst.
• Urinary infection or cystitis.

For a 4 kg cat, drinking more than 200 ml per day (dry food) is suspicious. If your cat eats wet food (rich in water), it naturally drinks less. Check out our cat feeding guide to understand the importance of hydration.

3. Change in Litter Box Use

The litter box is a valuable indicator of your cat's health. Pay attention to the frequency, consistency, and color.

Warning Signs

• More frequent or larger urine output: kidney failure, diabetes.
• Difficulty urinating (the cat stays in the litter box for a long time, strains, meows): urinary blockage. This is a life-threatening emergency in males. A cat can die within 24-48 hours if the blockage isn't resolved.
• Blood in urine: cystitis, stones, infection.
• Persistent diarrhea: parasites, food allergy, inflammatory disease.
• Constipation: megacolon, dehydration, lack of fiber.
• Going outside the litter box: pain (associates the litter box with pain), stress, urinary problem.

4. Change in Behavior

You know your cat better than anyone. Any sudden behavioral change deserves attention.

A Normally Social Cat Hiding

A sick or in-pain cat will often retreat to a quiet, dark place: under a bed, in a closet, behind furniture. If your usually present and social cat disappears for hours, that's a signal.

A Normally Calm Cat Becoming Aggressive

Pain can make a cat aggressive. If it growls, hisses, or bites when you touch a specific spot, it’s probably because it hurts.

Change in Sleeping Habits

Cats sleep 12 to 16 hours a day, which is normal. But if your cat is sleeping significantly more than usual or seems lethargic even when awake, that's a sign of discomfort.

5. Weight Loss

Gradual and unexplained weight loss is one of the most common signs of illness in cats. The problem is that their fur often hides the thinness.

How to Check: Run your hands over your cat's ribs. You should be able to feel them easily without pressing, but they shouldn't be protruding. If you can feel the vertebrae and pelvic bones prominently, your cat has lost too much weight.

Weigh your cat regularly (once a month is enough). A loss of 200 g in a 4 kg cat is equivalent to 4 kg in an 80 kg human. That's significant.

Common causes: hyperthyroidism, kidney failure, diabetes, cancer, inflammatory bowel diseases, parasites.

6. Vomiting

Occasional hairball vomiting is normal in cats. However, frequent vomiting (more than once a week) is not normal and shouldn't be dismissed.

When to Consult

• Repeated vomiting over 24 hours.
• Vomiting with blood.
• Vomiting accompanied by lethargy.
• Vomiting after every meal.
• Vomiting with weight loss.

Possible causes: hairballs (benign), gastritis, food allergy, foreign body (danger), kidney failure, pancreatitis, intestinal blockage (emergency).

7. Change in Coat

The coat is a mirror of your cat's internal health. A healthy coat is shiny, supple, and knot-free. A sick coat speaks volumes.

Warning Signs

• Dull and dry coat: nutritional deficiency, internal disease, dehydration.
• Excessive hair loss (outside of seasonal shedding): allergy, parasites, stress, hormonal disease.
• Unusual knots: a cat that no longer grooms itself is likely in pain or too tired.
• Bald patches: ringworm (contagious fungus, transmissible to humans), allergy, compulsive licking.
• Dandruff: parasites, allergy, overly dry environment.

For long-haired breeds like the Maine Coon or Ragdoll, a sudden stop in grooming is particularly noticeable and concerning.

8. Bad Breath

Unusually strong breath in cats can indicate:

• Dental problems: gingivitis, periodontal disease, tooth resorption (very common in cats). It's estimated that 50 to 70% of cats over 3 years old suffer from periodontal disease.
• Kidney failure: the buildup of toxins in the blood gives a breath that smells like ammonia.
• Diabetes: characteristic fruity breath (ketone bodies).
• Stomatitis: severe inflammation of the mouth, very painful.

Dental problems are the most common and underdiagnosed cause. A dental cleaning under anesthesia costs between 300 and 800 CHF in Switzerland, but it avoids much more costly complications.

9. Sneezing and Discharge

Sneezing

Occasional sneezing is normal (dust, irritation). Frequent sneezing, especially accompanied by nasal discharge, suggests:

• Cat flu (herpesvirus or calicivirus), check that your cat's vaccinations are up to date.
• Allergy.
• Foreign body (blade of grass in the nose).
• Secondary bacterial infection.

Eye Discharge

Clear and occasional tears are normal in some breeds. Colored discharge (yellow, green, brown) indicates infection. An eye that remains closed or half-closed is a sign of eye pain.

10. Limping or Difficulty Moving

If your cat is limping, hesitating to jump on the couch, or having trouble going down the stairs, don’t just chalk it up to age.

Possible Causes

• Arthritis: very common in older cats (90% of cats over 12 years old according to radiographic studies), but largely underdiagnosed.
• Injury: fracture, sprain, deep scratch.
• Neurological problem.
• Arterial thromboembolism: blood clot in the hind legs, absolute emergency (intense pain, cold and paralyzed legs).

A cat that stops jumping or playing is not "just old." It's probably in pain. Treatments for pain and arthritis exist and can significantly improve its quality of life.

11. Excessive or Unusual Meowing

A change in your cat's vocalizations can mean:

• Pain: plaintive meows, whines, especially at night.
• Hyperthyroidism: hoarse and frequent meows, often at night, in older cats.
• Deafness: in senior cats, hearing loss can cause very loud meows (the cat can’t hear itself).
• Cognitive dysfunction: the feline equivalent of dementia, in very old cats. Disoriented, the cat meows for no apparent reason.

12. Abnormal Breathing

A cat's normal resting breathing is silent and regular, between 20 and 30 breaths per minute. Any respiratory abnormality is potentially serious.

Emergency Signs

• Open-mouth breathing: in cats, this is ALWAYS abnormal (unlike dogs). It's a sign of respiratory distress. Immediate veterinary emergency.
• Rapid breathing at rest (> 40 breaths/minute).
• Breathing noises: wheezing, snoring (in a cat that wasn't snoring before).
• Abdominal breathing: the belly visibly rises with each breath.

Possible causes: feline asthma, pleural effusion, heart failure, pneumonia, tumor.

When to Consult in an Emergency?

Certain situations require immediate veterinary consultation (not tomorrow, not this weekend, now):

• Cat that hasn’t eaten for 48 hours.
• Difficulty or inability to urinate (especially in males).
• Open-mouth breathing.
• Paralysis of the hind legs (thromboembolism).
• Seizures.
• Falling from a significant height (window fall).
• Ingestion of a toxic substance.
• Trauma (car accident, dog bite).
• Bleeding that doesn’t stop.

In Switzerland, most major cities have 24/7 emergency veterinary clinics. Save the number of the nearest emergency clinic in your phone right now.

Prevention: The Best Remedy

The best way to catch diseases early is through regular monitoring:

• Annual check-up with the vet: complete clinical examination, blood tests if necessary. From 8 years old, a semi-annual check-up is recommended.
• Monthly weighing: keep track of your cat's weight to detect changes.
• Daily observation: get into the habit of observing your cat (appetite, litter box, behavior, coat).
• Up-to-date vaccinations: protect it against preventable diseases.

In Summary

Cats are masters of disguise. When they show signs of illness, it often means the problem is already established. Learn to observe the subtle signals: changes in appetite, behavior, weight, coat, or litter box use. If in doubt, consult your vet. Better to have a "false alarm" than a late diagnosis.

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