How Can I Tell If My Cat Is Sick?

Cats often hide signs of illness. It is a survival instinct and one reason I always tell pet parents to trust their gut if something feels “off.” The good news is you do not need veterinary training to spot early red flags. You just need to know what to watch for and when to act.

Below are practical, evidence-based tips I use as a veterinary assistant to help families in Frisco and beyond recognize signs of sickness early, collect helpful observations, and get the right care at the right time.

Quick note: This article is general education and does not replace veterinary advice. If you are worried, call your clinic.

First, know your cat’s normal

The clearest way to tell if your cat is sick is to notice a change from their baseline. Healthy cats can vary widely in personality and routine, so “normal” is your cat’s usual pattern.

• Appetite and water intake: How excited are they at meals? How often do you refill the water bowl?
• Litter box habits: Frequency, size, and ease of urination and stool.
• Energy and social behavior: More hiding, less greeting, less play.
• Grooming: A healthy cat usually keeps their coat tidy.
• Body weight: Slow weight loss can be one of the earliest signs of chronic disease.

Action tip: Weigh your cat monthly if you can. A baby scale works well for small cats, and a bathroom scale works by weighing yourself with and without your cat.

Common signs your cat may be sick

Some symptoms are obvious, like vomiting or limping. Others are subtle. Any of the following can indicate illness, pain, or stress, especially when they are new or worsening.

Changes in eating or drinking

• Not eating: In adult cats, not eating for 12 to 24 hours should prompt a call to your vet. For kittens, seniors, and cats with diabetes, kidney disease, liver disease, or other chronic conditions, call sooner.
• Eating less over several days: Can signal dental pain, nausea, kidney disease, hyperthyroidism, or other issues.
• Drinking more than usual: Common with kidney disease, diabetes, and hyperthyroidism.

Vomiting or diarrhea

• Occasional hairball: Can happen, but frequent hairballs are not “normal.”
• Repeated vomiting: Especially if your cat cannot keep water down, seems painful, acts very tired, vomits blood, or you suspect they ate string, toys, or other foreign material.
• Diarrhea lasting more than 24 to 48 hours: Or any diarrhea with blood, weakness, dehydration, or a kitten (kittens can decline quickly).

Litter box red flags (often urgent)

• Straining to urinate, frequent trips, or crying in the box: This can indicate a urinary tract problem.
• Urinating outside the box: Sometimes behavioral, but often medical, especially if sudden.
• No urine produced: This is an emergency, particularly in male cats, because a urinary blockage can become life-threatening without prompt treatment.

Breathing changes

• Open-mouth breathing, panting, or labored breathing: Emergency signs in cats.
• Rapid breathing at rest: Watch your cat while they are asleep or resting quietly and count breaths for 30 seconds (one breath equals chest rise and fall), then double it. Many cats are roughly in the 20 to 30 breaths per minute range at rest, but normal varies. If your cat is consistently over about 40 at rest, or breathing looks effortful, contact a veterinarian right away.

Colds and upper respiratory signs

• Sneezing, nasal discharge, watery eyes: Often a “cat cold,” but it can become serious, especially in kittens or cats who stop eating.
• Coughing or wheezing: Not something to ignore. Asthma and heart disease are on the list, so call your vet for guidance.

Behavior changes and hiding

• More hiding than usual: A classic sign of pain or illness.
• Sudden aggression or not wanting to be touched: Often pain-related.
• Not jumping up like they used to: Can be subtle arthritis or other chronic pain, especially in older cats.
• Confusion, staring, wobbliness: Needs prompt evaluation.

Coat, skin, eyes, ears, and mouth

• Dull, greasy, or matted coat: Can mean your cat feels too sick or painful to groom.
• Excessive scratching, hair loss, scabs: Allergies, fleas, skin infection, or stress grooming.
• Eye discharge, squinting, redness: Eye issues can worsen quickly and can be painful.
• Yellow tint to the whites of the eyes or gums: Jaundice can signal serious illness and should be checked promptly.
• Bad breath, drooling, pawing at the mouth: Dental disease is extremely common and can contribute to inflammation and overall health issues.

Other emergency red flags

• Sudden inability to use the back legs, severe pain, or crying out: Go in now.
• Severe belly swelling, repeated unproductive retching, or a hard, painful abdomen: Go in now.

Quick at-home check

You do not need to wrestle your cat into a full exam. A gentle, low-stress check can give you useful clues and help your veterinarian help you faster.

1) Watch before you touch

• Is your cat bright and responsive or withdrawn?
• Are they walking normally? Any limping or stiffness?
• Are they breathing comfortably with a relaxed body?

2) Check the basics

• Gums: Healthy gums are typically moist and pink. Pale, blue-tinged, very red, or tacky gums can be concerning.
• Hydration: Look for tacky gums, a dry mouth, or sunken-looking eyes. “Skin tent” tests can be unreliable in cats, so if you suspect dehydration, it is best to call your vet.
• Temperature: Only if you are trained and your cat tolerates it. When in doubt, let your vet handle it.

3) Look for pain signals

Cats often show pain through behavior, not crying.

• Hunched posture, tucked abdomen
• Not jumping up like they used to
• Flinching when picked up or when certain areas are touched
• Overgrooming one spot

Trust the change. If your cat is acting unlike themselves, that alone is a valid reason to call your vet.

Call the vet or go now

When pet parents hesitate, it is usually because they do not want to overreact. I understand that. Here are straightforward guidelines.

Call your veterinarian today if you notice

• Not eating for 12 to 24 hours (sooner for kittens, seniors, or cats with chronic disease)
• Vomiting more than once, or diarrhea lasting beyond 24 to 48 hours
• New drinking more or peeing more
• Sudden weight loss, persistent lethargy, or hiding
• Persistent sneezing, coughing, nasal discharge, eye discharge, or squinting
• Bad breath with drooling or trouble chewing

Go to an emergency clinic now if you notice

• Straining to urinate or unable to pass urine
• Open-mouth breathing, severe effort to breathe, or blue or pale gums
• Collapse, seizures, severe weakness, or unresponsiveness
• Suspected toxin exposure (lilies, rodent bait, antifreeze, certain human meds, and some essential oils, among many others)
• Trauma such as a fall, bite wound, or hit by car
• Sudden paralysis or severe pain

If you are unsure: Reach out. A quick phone conversation can save hours of worry and may prevent a small problem from becoming a big one.

What to track

Veterinary teams love details, because details shorten the time to a diagnosis. If you can, jot these down on your phone.

• When the signs started and whether they are getting better or worse
• Appetite: normal, decreased, or not eating
• Water intake changes
• Vomiting and diarrhea: how often and what it looks like
• Urination: frequency, straining, accidents, blood
• Any new food, treats, supplements, plants, or household products
• Current medications and preventives

Helpful tip: Bring a fresh stool sample if your clinic requests it, especially for diarrhea or suspected parasites.

Prevention that helps

You cannot prevent every illness, but you can stack the odds in your cat’s favor and catch issues earlier.

• Annual or twice-yearly exams: Many cats benefit from checkups every 6 months as they age.
• Routine lab work: Bloodwork and urinalysis can uncover hidden kidney disease, thyroid disease, diabetes, and more.
• Dental care: Dental disease is common and painful. Prevention and timely cleanings matter.
• Parasite prevention: Fleas, ticks, intestinal parasites, and heartworms can affect cats too.
• Weight management: Extra weight increases risk for diabetes, arthritis, and urinary issues.
• Reduce stress: Provide vertical space, safe hiding spots, consistent routines, and clean litter boxes.

Bottom line

If your cat is not acting like themselves, do not wait for things to become obvious. Cats often whisper before they scream. Early care is usually simpler, more effective, and less expensive.

Quick next step: Pick one baseline habit to monitor today, like appetite or litter box output. Small observations add up to big answers when your cat needs help.