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Cats hide illness like pros — but they can't hide everything. Spot these warning signs before it's urgent."
Common Signs of Illness in Cats You Shouldn't Ignore
Cats are pros at looking perfectly fine while they feel terrible. That stoic "I'm fine" face is adorable — until it isn't. The trick for cat owners is to learn the subtle clues our felines give us and know when to act. This guide breaks down common warning signs, what they could mean, and what you should do (including when to call the vet right away). I'll keep it practical and no-nonsense, with checklists you can actually remember when that weird thing happens at 2 a.m.
Why cats hide sickness (short version)
Cats evolved as both predators and prey — showing weakness could make them targets. That instinct remains. So unlike some dogs who tell you immediately when they're off, cats often dial it down. That's why small changes matter: what looks "a bit off" to you might be the first visible sign of something important.
The top signs to watch for (and what they often mean)
1. Appetite change — eating less or not at all
What to watch: reduced interest in food for more than 24–48 hours, refusing favorite treats, or sudden scavenging/overeating changes.
Why it matters: Appetite loss (anorexia) is a common sign of many illnesses — from dental pain to kidney disease to infections. If your cat stops eating for more than a day (especially adult cats — kittens are different), contact your veterinarian. Long periods without eating can lead to hepatic lipidosis (a dangerous liver problem) in cats. ASPCA
What to do: Try warming wet food, offering something smelly like tuna ( a small amount), but don't force-feed unless instructed by your vet.
2. Lethargy — sleeping more, low energy, hiding
What to watch: a cat that's less playful, not engaging, sleeping in odd places, or hiding for long stretches.
Why it matters: Lethargy is a non-specific but essential sign. It often accompanies systemic problems such as infection, pain, anemia, and metabolic disease. If lethargy is sudden, severe, or paired with other signs (vomiting, breathing trouble), seek veterinary care immediately. PetMD
What to do: Note how long it's been, other symptoms, and any recent events (new food, toxin exposure). A short nap isn't a crisis; a cat that won't get up to eat or respond may need urgent attention.
3. Vomiting or diarrhea
What to watch: repeated vomiting, vomiting with blood, persistent diarrhea, or stool with mucus/blood — especially if your cat is also depressed or not drinking.
Why it matters: Occasional hairball vomit is often normal, but ongoing vomiting/diarrhea can cause dehydration or indicate infection, toxins, foreign body obstruction, or organ disease. If vomiting/diarrhea continues for more than 24–48 hours or is severe (bloody, frequent), call the vet. ASPCA+1
What to do: Keep litter-box samples aside (vet may want them), withhold food for a few hours for adult cats (check with your vet first), and ensure clean water is available. If you see signs of dehydration (see below), get help.
4. Changes in drinking and urination
What to watch: increased or decreased drinking, straining to urinate, frequent trips to the litter box with little output, or urinating outside the tray.
Why it matters: These can be signs of urinary tract infection, urinary obstruction (an emergency, especially in male cats), kidney disease, or diabetes. Straining and lethargy with repeated trips to the litter box is an urgent situation. RSPCA
What to do: If your cat is straining, crying when trying to pee, or has only tiny drops — go to an emergency vet right away. For increased drinking/urinating, book a vet visit to check the kidneys and blood sugar.
5. Breathing problems — coughing, wheezing, fast or labored breathing
What to watch: open-mouth breathing, very fast breaths, wheezing, noisy breathing, or blue-tinged gums.
Why it matters: Respiratory distress can be life-threatening (asthma, heart disease, severe infection, fluid in the lungs). Any increased effort to breathe warrants immediate veterinary evaluation. UrgentVet | Home
What to do: Keep the cat calm and warm; transport to the vet immediately. Don't attempt nebulizers or treatments unless advised.
6. Sudden weight loss or gain
What to watch: visible ribcage, clothes not fitting on the scale, bloating, or rapid weight changes.
Why it matters: Weight loss can point to hyperthyroidism, diabetes, cancer, or chronic kidney disease. Rapid weight gain, abdominal swelling, or fluid buildup also needs urgent evaluation. Track weight at home if possible.
What to do: Record timeline and amount of weight change; bring this to your vet appointment.
7. Changes in grooming — matted fur, greasy coat, over-grooming, or no grooming
What to watch: patchy fur, clumps, or a sudden change in grooming behavior (too much licking or none at all).
Why it matters: Over-grooming can signal skin problems, stress, or pain (cats lick sore spots). Under-grooming may mean arthritis (can't reach), dental pain, or systemic illness. Skin disease and dental disease are both common in cats. RSPCA
What to do: Look for skin lesions, fleas, or sore spots; if your cat can't groom due to pain, ask the vet about pain control.
8. Eye or nose discharge, squinting, or eye cloudiness
What to watch: red or cloudy eyes, pus-like discharge, persistent sneezing, or bad-smelling discharge.
Why it matters: Respiratory infections, conjunctivitis, or more serious eye diseases can be the cause. Eye problems left untreated can lead to vision loss. ASPCA
What to do: Wipe gently with a soft, damp cloth and monitor. If the eye suddenly becomes painful or cloudy, or if your cat won't open it, see the vet quickly.
9. Bad breath, drooling, or difficulty eating
What to watch: mouth odor that's dramatically worse than usual, visible swollen gums, drooling, or reluctance to chew.
Why it matters: Dental disease is prevalent and painful. Severe dental infections can affect internal organs over time. If your cat drops food or chews on one side, suspect oral pain. RSPCA
What to do: Ask your vet for a dental check. Don't try to inspect the mouth deeply if your cat is painful — a fearful/painful cat can bite.
10. Lumps, wounds, or bleeding
What to watch: any new lump, swelling, persistent bleeding, or wounds that don't heal.
Why it matters: Lumps can be benign or malignant; any new lump that grows, is painful, or changes should be checked. Open wounds risk infection.
What to do: Photograph the area, note any change, and have your vet examine it. Minor cuts can be cleaned, but deep wounds, punctures, or heavy bleeding require immediate care.
11. Neurologic signs — tremors, seizures, disorientation
What to watch: stumbling, head tilts, loss of balance, seizures, or sudden aggression.
Why it matters: Many serious causes — toxins, metabolic imbalances, brain disease — can cause neurologic signs. Seizures and collapse are emergencies.
What to do: Keep your cat safe during a seizure (don't put your hands in the mouth), note the duration, and go to emergency care if it's your cat's first seizure or one that lasts long.
Dehydration checks you can do at home.
If your cat has vomiting, diarrhea, or hasn't been drinking, check for dehydration:
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Skin turgor test: Gently lift the skin at the scruff or between the shoulder blades and release. It should snap back quickly; if it "tents," that suggests dehydration.
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Gums: Gums should be moist and pink. Dry/tacky gums are concerning.
If the skin or gums are dry, get veterinary help — dehydration in cats can become serious quickly.
When to call the vet — short checklist
Call your vet or go to emergency care right away if you see any of these:
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Trouble breathing, open-mouth breathing, or blue/pale gums. UrgentVet | Home
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Straining to urinate or only producing drops (male cats at high risk). RSPCA
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Seizures, collapse, or unconsciousness. rspcavic.org
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Continuous vomiting or diarrhea for more than 24 hours, or bloody vomit/stool. ASPCA+1
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Suspected poisoning (e.g., antifreeze, human meds, toxic plants) — contact vet immediately. RSPCA+1
For less urgent but still concerning signs (e.g., appetite loss >48 hours, weight loss, skin/ear problems, dental concerns), schedule a vet visit within a couple of days.
First-aid basics (what you can do safely at home)
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Keep calm: Cats pick up stress: a quiet carrier and low lighting help.
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Control bleeding: Apply gentle pressure with a clean cloth; seek vet care for deep wounds.
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Prevent further toxin exposure: If you suspect poisoning, remove access and bring the packaging to the vet. Don't induce vomiting unless a professional tells you to. RSPCA
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Hydration: Encourage water; offer low-sodium chicken or broth (no onion/garlic). If you can't get fluids in and dehydration is suspected, the vet can give subcutaneous fluids.
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Don't medicate human drugs: Never give human meds (ibuprofen, acetaminophen, etc.) — they can be deadly to cats.
Prevention and long-term care tips
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Routine vet visits and bloodwork — baseline labs can catch kidney disease, thyroid issues, and diabetes early.
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Dental care — dental disease is hugely common; annual checks and cleanings help. RSPCA
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Parasite control and vaccinations — preventable diseases are less stressful and cheaper than treatment.
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Safe home — watch for toxic plants, antifreeze, human meds, and human foods that can poison cats. RSPCA+1
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Weight management and enrichment — obesity hides illness and causes joint problems; activity and play help.
When a vet visit might include (what to expect)
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Physical exam, weight, temperature.
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Bloodwork and urine testing (kidney, liver, thyroid, glucose, infection markers).
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Fecal test for parasites.
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X-rays or ultrasound for internal concerns.
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Dental exam under anesthesia if needed.
Knowing this helps you feel prepared and ask the right questions.
A few common myths to skip
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"My cat will tell me if something's wrong." Not always — many cats hide illness.
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"If my cat still plays occasionally, they're okay." A cat might play for a few minutes but still be unwell. Look at the whole picture.
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"Natural remedies always help." Many "folksy" solutions aren't tested and can delay necessary treatment; always check with your vet.
Quick recap — what to do right now if you notice something
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Make notes: when it started, what changed, appetite/water, litter-box output, any odd smells or discharges.
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Do a quick dehydration check and note temperature/behavior.
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If any serious red flags (breathing trouble, collapse, inability to urinate, seizures, suspected poisoning), go to emergency care now.
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Otherwise, book a vet appointment and bring notes and a stool/urine sample if possible.
Amazon items that can help cat owners (what I found)
I searched for valuable, practical items related to monitoring or managing cat health. These are examples of products many owners find useful — thermometers, pill tools, grooming tools, and first-aid-ish supplies.
Short list of items I found (examples; check current availability/prices on Amazon):
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Digital pet thermometer — handy for checking a pet's temperature at home. (example listing found).
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Pill dispensers/pill injectors/pill poppers — make med administration easier and less stressful (multiple low-cost options available).
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Pet first-aid kit / oral syringes — small kits, syringes for giving fluids/meds, basic wound care supplies (search Amazon for "cat first aid kit"). (examples available).
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FURminator de-shedding brush — helps with hairball management and spotting skin issues sooner.
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Books on natural and conventional pet health — e.g., general guides and references (example title located)
Final thoughts
You don't need to be a vet to keep your cat safe — you need to notice changes and act. Minor signs often come before big problems; a note in your phone about "when it started" and a quick dehydration check can make a huge difference. If something feels wrong, trust your instincts: getting a checkup earlier usually means a more straightforward fix and less stress.
Sources (key references used)
