Cats don’t always show illness the way you’d expect. They don’t whine or limp for attention. Often, they go quiet. They hide. They sleep more, eat less, or just act… off. That’s why knowing how to tell if your cat is sick starts with paying attention to what’s normal and noticing when that changes.
Some cats are clingy, others aloof. Some chatter, others don’t make a sound. The point is: you know your cat’s baseline better than anyone. When that baseline shifts even slightly, it could be a clue. And when it comes to illness in cats, small clues matter.
Before we dive into the signs of illness, let’s start with what makes your cat’s normal behavior your most valuable tool.
How to Tell if Your Cat is Sick
You can tell your cat is sick by observing its condition and behaviour. Cats are stoic creatures. They rarely cry out or draw attention when something’s wrong. That’s why learning how to tell if your cat is sick often comes down to noticing the quiet changes.
One of the first signs? A shift in appetite or weight loss.
Changes in Appetite or Weight
If your cat suddenly eats less or stops eating altogether, that’s a concern. The same goes for unusual hunger. A noticeable increase or decrease in appetite can be a signal that something isn’t right.
Vomiting and Diarrhea
A hairball here and there isn’t a big deal. But if your cat is vomiting more than once a day, or has diarrhea that lasts longer than 24 hours, it’s worth paying attention.
Blood, a strange smell, or anything you haven’t seen before; these may be symptoms of a sick cat. That’s your cue to call the vet. Cats hide things well, but their stomach and gut symptoms usually don’t lie.
Lethargy and Weakness
If your normally active feline friend suddenly becomes lethargic or spends most of its time sleeping, it might feel unwell. Your cat may appear to be lying around more and not wanting to engage in playtime as much as usual. While cats do sleep a lot, a significant decrease in activity levels is worth noting.
Changes in Grooming Habits
If your cat suddenly stops grooming, don’t brush it off. Cats are clean by nature. A rough-looking coat usually means something's wrong. They may be in pain, feeling low, or too unwell to bother.
On the other hand, if they start licking one spot over and over, especially if the fur’s thinning or there's hair loss, it could be stress, allergies, or skin irritation.
Respiratory Issues
If your cat starts breathing through their mouth, it’s not something to brush off. Mouth breathing in cats usually signals trouble. You might also notice shortness of breath, a fluttering chest, or wheezing sounds that weren’t there before.
A sneeze here and there, or a bit of clear discharge from the eyes or nose, might pass on its own. But if your cat looks like they’re working just to breathe, that’s not normal, and it’s not safe to wait.
Behavioural Changes
Cats won’t come out and tell you they’re in pain, but they’ll act differently. The friendly one that usually curls up beside you might suddenly keep to themselves. Others may flinch at touch, stop greeting you at the door, or act withdrawn in ways that don’t feel like them.
These aren’t just mood swings. Subtle changes in behavior are often their quiet way of saying something’s wrong.
Changes in Litter Box Habits
When a cat suddenly stops using the litter box, it’s rarely about rebellion. It’s communication. Straining to urinate, spots of blood, or going outside the box are all signs that your cat may be ill.
Sometimes it’s pain. Sometimes it’s stress. Either way, litter box changes are one of the clearest ways your cat might be telling you they’re sick.
What Are the Most Common Diseases in Cats and Their Symptoms?
While signs like vomiting or lethargy are important to notice, they often indicate more serious underlying issues. Understanding what conditions these symptoms may indicate can help you act more quickly and confidently. Here's a quick reference table of common diseases in cats and what symptoms of a sick cat to look out for:
Disease | Key Symptoms |
Upper Respiratory Infection (URI) | Sneezing, nasal discharge, coughing, fever, loss of appetite |
Urinary Tract Infection (UTI) / FLUTD | Frequent urination, straining, blood in urine, crying in the litter box |
Chronic Kidney Disease (CKD) | Increased thirst, frequent urination, weight loss, dull coat, bad breath |
Weight loss, increased appetite, vomiting, hyperactivity | |
Increased thirst, frequent urination, lethargy, unexplained weight loss | |
Dental Disease | Drooling, bad breath, pawing at the mouth, reluctance to eat |
Arthritis / Chronic Pain | Limping, stiffness, reluctance to jump, overgrooming joints, irritability |
If any of these signs of illness sound familiar, reach out to your vet. Diagnosing early can make a world of difference in your cat’s comfort and longevity.
When Should You Take Your Cat to the Emergency Vet?
Some symptoms mean you don’t wait. Call your vet or go to the nearest emergency clinic if you see:
Your cat breathing with an open mouth
They collapse or can’t move their legs
Vomiting or diarrhea that doesn’t stop, especially if there’s blood
Seizures or body tremors
A swollen face or signs of an allergic reaction
A hard, bloated belly that looks painful
They can’t pee or strain in the litter box without results
Sudden blindness or acting lost and confused
Cats don’t show pain the way people do. If it feels urgent, it probably is. Don’t second-guess.
What to Do If You Think Your Cat Is Sick
You know your cat. If something feels off, it probably is.
Start by paying attention. Not just the big symptoms, but to the small stuff: are they a little quieter? Sleeping somewhere unusual? Eating slower than usual? These subtle changes in behavior are often how it begins.
Monitor the Symptoms
Every cat is different. What’s strange for one might be normal for another. The key is change. If they’re usually clingy and now they’re hiding, or they’re playful and now barely moving, that shift matters.
Sometimes it’s nothing. Sometimes it’s the first sign of a health problem. Either way, it’s better to check than to guess.
Consult the Vets
If things don’t improve in a day or two, call your vet. If anything gets worse, act sooner. It’s always better to ask than to guess.
Document Symptoms
Make a list of what you’ve seen. Include when the symptoms started and how long they’ve lasted. If the signs come and go, a short video can help your vet see what you’re seeing.
Follow Medication
Some cats are difficult to administer pills or liquids to. Try hiding them in food or asking for an easier option. But don’t skip doses. Stopping too early can make treatment more difficult later.
Give the Right Meals
If your vet recommends a new diet, follow it closely. This can help with recovery, especially for long-term issues like kidney disease or diabetes.
Follow-Up Appointments
These visits are important. They help your vet check how things are going and change the treatment if needed. Even if your cat looks better, still go.
How to Prevent Your Cat from Getting Sick
It’s always easier to keep your cat healthy than to treat illness after it starts. A few small habits can go a long way in protecting them from serious problems later on.
Regular Vet Check-ups
Even if your cat appears healthy, bring them in for a check-up at least once a year. For older cats, every six months is better. These visits help us catch signs of illness early, before your cat shows any symptoms.
Vaccinations and Preventive Care
Your cat should be protected against core viruses like upper respiratory infection (FVRCP) and rabies. If they go outdoors or mix with other cats, they’ll need extra protection, like the feline leukemia (FeLV) vaccine.
Balanced Diet
Cats require diets tailored to their age and specific health needs. A growing kitten doesn’t need the same food as a senior with kidney disease. Focus on protein first, then balance with healthy fats and vitamins.
Prescription diets can help manage conditions like urinary problems, allergies, or weight gain, but only when truly needed.
Exercise and Mental Stimulation
Indoor cats still need playtime. Without it, weight gain creeps in, and with it, risks like diabetes or arthritis. Even a few minutes of chasing a toy mouse or jumping after a wand can make a difference. It also helps with mood and behaviour.
Parasite Protection
Fleas and worms don’t care if your cat stays indoors. Monthly protection helps prevent serious infections and skin irritation caused by parasites.
Grooming
Brushing helps keep their coat healthy and gives you a chance to spot signs that your cat may be sick, like hair loss, sores, or tender spots.
Cats that stop grooming might not feel well. Cats that overgroom might be anxious or itchy. Either way, it matters.
When it’s time for a bath, use a cat-safe shampoo. Water should be lukewarm. Dry them off completely, especially if your home is cold.
Dental Health
Bad breath isn’t just a nuisance. It usually means dental disease or infection. Chewing, rinsing, or professional cleaning helps stop problems early.
If brushing isn’t possible, ask about dental chews, water additives, or professional cleaning. The earlier we treat dental issues, the easier it is on your cat.
Avoid Stress
Too much stress can lead to illness in cats. Whether it’s a loud home, travel, or changes in routine, do your best to keep things calm and familiar.
Studies show that even healthy cats may start exhibiting signs of illness, such as vomiting, changes in appetite, or avoidance of the litter box, if their routine is disrupted.
For example, a 2011 Ohio State study found that when healthy cats experienced environmental changes, sickness behaviors increased nearly 3‑fold, even in those without any underlying health issues. This highlights how sensitive feline friends can be to stress, and why observing subtle changes in behavior is so important.
Senior Cat Wellness
Once your cat hits 7, their needs change. Older cats are more likely to develop chronic issues like kidney disease, dental disease, or hyperthyroidism. Regular bloodwork can help us act before your cat even shows symptoms.
How to Check Your Cat at Home: Vet-Style Tips
You can do simple health checks at home to spot early warning signs:
Skin Tent Test for Dehydration
Gently pinch the skin at the back of your cat’s neck. If it stays “tented” and doesn’t quickly snap back, your cat may be dehydrated.
Eye and Nose Check
Eyes should be clear. Discharge fromthe eyes or nose could be a problem.
Check the Gums
Healthy gums are pink. Pale, blue, or red gums can mean illness in cats.
Look for Limping or Stiffness
Does your cat avoid stairs or high places it used to love? Subtle changes in movement can mean pain or arthritis.
Grooming Behavior
Excessive licking, bald spots, or a greasy, unkempt coat often signal stress, illness, or arthritis.
“Cats are incredibly stoic creatures. They often suffer in silence, which is why early detection is key. If you notice even small changes in your cat’s behaviour or habits, don’t ignore them. It could mean the difference between a simple fix and a serious health problem.”
- Dr. Soheyl Simaei
Final Thoughts
Watching over a cat means more than feeding or playing. It means noticing when something’s off before it gets worse.
Learning how to tell if your cat is sick isn’t just helpful. It’s how you catch problems early and avoid bigger ones down the line. If your cat seems different, don’t second-guess it. Call your vet.
They rely on you to speak up when they can’t.
Frequently Asked Questions
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