A question that we often get asked as vets is how owners can tell if their cat has an infection. In some cases, the answer to this question is quite straightforward, as there will be an obvious sign such as vomiting or diarrhoea, indicating that your cat is unwell. However, in many cases, the signs of an infection can be very subtle. This makes it very difficult to tell if your cat is under the weather. 

Infections can be caused by bacteria, viruses, or, less commonly, fungi. They can affect any part of the body. Infections can present as a range of symptoms, and many of these symptoms are common to other diseases, and so it is always important to seek the advice of your vet if you are worried about your cat.

It is a really good idea to get into the habit of giving your cat a quick check over when they come for a cuddle. This makes it easier to spot any abnormal signs early. If possible, get your cat used to having all areas of their body handled, including their mouth and their ears. If there is a problem, they will be more comfortable with you checking.

Signs that your cat is unwell

There are some important signs that you can look out for at home that indicate that a trip to the vets is warranted and that your cat may have an infection:


Has your cat recently developed smelly breath (halitosis) or started excessively drooling? Can you see any tartar building up on their teeth or any redness in the gums? Do they seem to be in any pain when they are eating? These are all possible signs of periodontal disease in cats (infection and inflammation around the teeth).


Has your cat recently developed any abnormal discharge from their eyes (particularly discharge that is yellow or green in colour)? Do they seem to be in pain or squinting? Is the third eyelid showing across their eye? If you notice any problems with your cat’s eyes, then it is important to get them checked out ASAP. 


Can you see any abnormal discharge in your cat’s ears, and do they seem to be smelly? Has your cat been scratching around their ears? These are all signs of a possible ear infection.

Respiratory Tract

Has your cat had any recent coughing or sneezing? Do they have any discharge from their nose? Is their breathing noisy? Do they seem to be having any trouble breathing? Respiratory tract infections in cats can range from fairly minor problems to life threatening ones, and it can be quite difficult to tell how serious the problem is, therefore we always recommend seeking advice from your vet straight away if you have any concerns about your cat’s breathing. 

Gastrointestinal Tract 

Has your cat started vomiting or recently developed diarrhoea? Are they eating less than usual? These are all possible signs that they may have a problem with their digestive system. Often, gastrointestinal infections are self-limiting (which means they will clear up on their own), but you should always ask your vet’s advice in case it is a sign of something more serious. 

Urinary Tract

Have you noticed any changes in your cat’s litter tray habits? Are they urinating more frequently? Are they showing any signs of pain when they are urinating? Do they seem to be straining excessively when urinating? Have you seen any blood in their urine? Are they urinating in unusual or inappropriate places? Have you noticed any changes in your cat’s drinking? Problems with the urinary tract in cats, including urinary tract infections, can be very serious, particularly in male cats, and warrant an urgent check with your vet. 


Have you noticed your cat grooming more frequently than normal? Have you noticed any scabs on the skin, or any redness? Is there any hair loss? Are there any obvious injuries, or any swollen or painful areas? Skin infections, wounds and abscesses are all things that we see quite commonly in the veterinary clinic.

Bones and Joints

Have you noticed any change in how your cat is moving around? Are they obviously lame? Do they seem reluctant to jump? There are many conditions that can cause changes in how your cat is moving, including infections, and an examination by your vet is necessary to help pinpoint the problem. 

BUT…..Cats are the masters of disguise!

It makes our job as a vet relatively easy when cats come in with any of the symptoms that we have already talked about. More commonly, however, we are presented with a cat that’s ‘just not quite right’ and that is when the detective work begins. Cats are very good at hiding the signs of being unwell, and even if they do have one of the more obvious symptoms, such as vomiting or changes in urination, they will often only display these in private, for example by toileting outside. 

Signs that a cat may have an infection can be very difficult to spot and can be as subtle as sleeping a little bit more than usual, not wanting to go outside (or spending more time outside), being withdrawn (or in some cases, wanting more attention), being grumpy, not grooming themselves as much or changes in appetite or thirst. These very vague signs can be seen with a huge variety of conditions and so it can be very difficult to work out what is wrong. 

If you do feel that your cat is ‘just not quite right’, please do not ignore it, but instead book a consultation with your vet – we will always take you very seriously!

How will my vet work out what the problem is?

When you take your cat to the vet, they will start by asking you lots of questions about how your cat has been recently. They will then perform a full clinical examination. Often the history and clinical examination are sufficient to diagnose what is wrong with your cat. In some cases, however, further tests, such as blood and urine tests, swabs and imaging (x-rays and ultrasound scans) may be necessary to get to the bottom of the problem.

In summary…

If you have any concerns about your cat, no matter how small the change in them is, it is always best to seek the advice of your vet. Cats are very good at hiding signs of illness, but your vet will be able to use a combination of any changes you have noticed about your cat, their clinical expertise and perhaps some additional tests to work out what is wrong.

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