How To Know If Your Cat Is Sick?

Updated August 22, 2023

Sometimes, you just feel that something isn’t right with your pet. But how to know if your cat is sick for sure?

Before you bring your cat to a vet, evaluate what has changed in your furry friend’s appearance and behavior.

A sick cat may have changes in appetite, energy levels, affection, social interactions, and vocalization.

Note that what’s normal for one cat may not be typical for another one. You know your cat best and can spot abnormalities better than any professional.

But some tips on how to tell if your cat is sick are universal. Look out for odd discharge, poor coat quality, gastroenteric issues, and foul odor.

Changes in Appetite

Sick cats almost always experience changes in appetite, either being reluctant to eat entirely or eating more than usual. Some cats become picky about their food or develop odd dietary habits.

Cats may have appetite changes due to dental problems, fever, cancer, mental disorders, gastroenteric issues, and numerous other conditions.

Cats with kidney diseases may lose appetite but have increased thirst.

Excessive thirst in cats may also signal diabetes and hyperthyroidism, a condition caused by an excess of the thyroid hormone responsible for metabolic function regulation.

Sometimes, changes in appetite are triggered by stress, heat, or other temporary factors, but if your cat hasn’t eaten for 24 hours, seek veterinary help. Anorectic cats can develop hepatic lipidosis, also called fatty liver disease.

The fatty liver disease further suppresses a cat’s appetite, which doesn’t help fight the initial cause of appetite loss.

Loss Of Interest in Play

Another sign a cat is sick is a loss of interest in play and overall changes in activity levels. The reasons why a cat is reluctant to play are numerous, including stress, heat, aging, and medical conditions.

So, reluctance to play alone doesn’t yet indicate that a cat is sick, but it’s an important supporting symptom.

Senior cats typically lose interest in playing gradually and not entirely. They may not run around anymore, but they will pay attention to a moving wand toy regardless.

Sure, some cats are naturally lazy. However, if your cat suddenly lost interest in its toys, you may need to start worrying.

Sick cats may sleep longer than usual and not express their hunting instinct. Sometimes, ill cats feel disoriented and cannot walk straight or jump.

Changes in Vocalization

There’s no universal norm when it comes to feline vocalization. Some cats never meow, whereas others talk non-stop. Excessive vocalization is typical for specific cat breeds, including Siamese and Oriental.

However, sudden changes in vocalization usually indicate a problem. For example, if your cat suddenly started crying at night, it may be asking you for food or attention, but it may also be signaling pain.

The most common causes of excessive vocalization in cats are thyroid excess and cognitive dysfunction. The thyroid is a hormone responsible for metabolic function regulation, and its excess can make a cat restless and talkative.

Cognitive dysfunction disorder in cats is the equivalent of dementia in humans, occurring in senior felines. However, constant meowing may also signal physical pain – for instance, a cat crying in the litter box may have kidney stones.

Loss of voice is also a cause for concern. A cat that used to be talkative but suddenly stopped meowing may be stressed or have respiratory issues.

Changes in Behavior

Changes in behavior can signal a variety of medical conditions. Aggression, anxiety, panic, decrease in affection levels are concerning signs of either physical pain or mental disorders.

If a cat never liked cuddles or has despised other animals since kittenhood, there’s nothing to worry about – each cat is different and has a unique personality.

But if your cat has turned from a loving, affectionate pet into a hissing and growling disaster, it may be unwell. Sick cats tend to avoid social interactions or, on the opposite, suddenly become excessively affectionate.

Note that cats are sensitive to changes in their living environment, so changes in behavior are expected after moving houses or introducing the cat to a new pet or baby. But if there were no triggers for behavioral changes, seek veterinary help.

Weight Loss or Gain

Weight loss or gain in cats can be related to changes in appetite, but not necessarily. Moderate weight gain is typical for senior and fixed cats. However, if a cat is gaining weight rapidly and for no visible reason, it may be sick.

Intact female felines gain weight during pregnancy – that’s the least worrying cause of weight changes. Fluid retention caused by kidney diseases also causes sudden weight increase.

Cats suffering from arthritis and other skeletal or muscular conditions become inactive and gain weight despite regular appetite.

Another potential cause of sudden weight gain in cats is acromegaly, a tumor that triggers excessive growth hormone secretion.

Weight loss is no lesser cause for concern, especially if the cat is eating as usual.

The most common causes of sudden weight loss in cats are cancer, diabetes, anemia, infectious peritonitis, gastroenteric issues, parasites, and hyperthyroidism.

Many senior cats begin losing weight before dying because of organ failure. To identify the root of the issue, a veterinarian should conduct a urinalysis, fecal analysis, and a complete blood count.

Vomiting, Diarrhea, Frequent Litter Box Visits

Vomiting, diarrhea, flatulence, and other gastroenteric symptoms are apparent signs a cat is unwell. Owners often think their cats vomit because of hairballs or have diarrhea because of new food.

Sometimes, this is true. New foods can indeed cause gastroenteric upset or trigger an allergic reaction. But if a cat develops these symptoms suddenly and for no apparent reason, it may be severely sick.

Vomiting and diarrhea in cats may indicate a parasitic infestation, bacterial gastroenteric infection, inflammatory bowel disease, obstruction, cancer, and numerous other conditions.

The look of the vomit can tell a lot about its cause. Although inspecting a cat’s vomit isn’t particularly amusing, look at it – if you see blood or something resembling coffee grounds, seek urgent veterinary help.

Frequent litter box visits signal health issues related to the urinary or gastroenteric tract.

If a cat visits the litter box frequently and makes crying noises, it may have an infection, bladder stones, diabetes, kidney disease, or hormonal disbalance.

Dull Coat, Increased Shedding, Excessive Grooming

A cat’s coat condition largely depends on its health state. If a cat’s coat looks dull, is greasy, or changes color, it may not be getting sufficient minerals and vitamins from food or be sick.

Dehydration often causes feline fur to appear lifeless. Drinking water is vital for any cat, so if your pet doesn’t drink enough, you should determine why.

A poor coat quality doesn’t necessarily indicate issues with skin. Sometimes, a cat’s coat looks different because of dental or mental problems preventing it from grooming itself.

Excessive shedding is another alarming sign a cat is sick. Cats shed year-round, and in spring and autumn, they tend to shed more than usual. But if a cat started shedding a lot out of season, it may be dealing with a disease.

Increased shedding in cats may be caused by parasite infestation, allergies, cancer, thyroid deficiency, and other conditions. Often, cats lose too much fur due to excessive grooming.

Excessive grooming can be behavioral, caused by a compulsive disorder or stress, and medical, caused by parasites. Cats may lick themselves more frequently in a particular area to relieve pain.


A healthy cat should have no discharge from the nose, eyes, or under the tail. Sometimes, cats may have watery eyes – that’s normal, particularly for cats with flat faces like Persian and exotic cats.

However, if the discharge is excessive or has a yellowish, reddish, or brownish color, the eyes are inflamed, and the cat is constantly trying to rub its eyes, it may be dealing with a bacterial or virus infection, such as calicivirus.

Other causes of runny eyes in cats include allergy, conjunctivitis, corneal disorders, and blepharitis. If a cat leaks fluid from under the tail, it may have anal gland inflammation or a gastroenteric disease.

Pregnant felines should have no discharge unless the labor begins. When the labor starts, the discharge should be colorless. If it’s yellowish or greenish, the cat needs urgent veterinary help.

Bad Odor

Like any animal, cats don’t always smell pleasant, but they shouldn’t smell repulsive either. A foul smell from a cat’s mouth may indicate poor dental hygiene but also dental diseases and gastroenteric issues.

A healthy cat’s skin shouldn’t smell. A foul odor can develop due to parasitic or bacterial infections or cancer. However, sometimes, the issue lies in poor grooming.

If a cat’s ears smell bad, it may be suffering from an infection or ear mites. Since cats are skillful groomers, they tend to keep their rear end clean, but if it emanates a foul odor, a cat may have a gastroenteric illness.

Sometimes, cats are unable to properly clean their rear end because of arthritis or obesity.

Image credit: Pixabay

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