Bad breath in cats

Black cat on white background


While we may not expect our cats to have breath as fresh as ours, if they have really smelly breath it could be the sign of an underlying medical problem.

Bad breath is often due to problems with the teeth or gums but can also be due to more serious medical conditions.

Take your cat for a check-up if you notice they have bad breath, or any other mouth problems. Your vet will be able to examine the mouth fully (and safely!), which may not be easy for you to do at home.

My cat has bad breath, is that normal?

If you notice your cat’s breath is smelly, it’s likely that there is an underlying problem. Look out for other symptoms such as:

Photo of tartar build up on cat's tooth

Tartar build up can cause bad breath in cats.

Causes of bad breath in cats

Tooth and gum disease

Tooth and gum diseases such as tartar build up, infections, sore mouth or gums and abscesses very often cause bad breath.

Kidney disease

Kidney disease causes waste products to build up in the body. This can cause their breath to smell like ammonia (similar to bleach).

Things stuck in the mouth

If something gets stuck in your cat’s mouth or throat (such as a stick or a bone) it will often start to smell. You may also notice your cat pawing at their mouth or face.

Mouth cancer

Cancers in the mouth often become infected and start to smell. Your vet may need to put your cat under anaesthetic or sedate your cat to look properly in the mouth. Cancers in this area can be difficult to treat but finding them early can help.

Liver disease

Liver disease leads to waste products entering the lungs. This causes a foul, sweet, musty breath.

Airway infections

Bacterial infections in the lungs, sinuses or windpipe can cause bad breath.


If diabetes isn’t properly managed the body starts to break down fat, this causes the breath to smell sweet (similar to pear drops or nail polish remover).

Gut problems

A gut infection or blockage will often make the breath smell bad. You will often notice other signs such as diarrhoea, vomiting or stomach pain before noticing the bad breath.


Some diets can cause a cat’s breath to be smellier than others. Fish based diets can cause a fishy smelling breath.

When to contact your vet

Very smelly breath is not normal. If your cat’s breath is noticeably bad, there’s likely to be an underlying cause which needs diagnosis by your vet.

You know your cat best. If you are concerned it’s always best to contact your vet.

Published: October 2018

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Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst