Bad breath in cats


  • Bad breath (halitosis) is not normal, even in older cats – it usually indicates a problem.
  • Take your cat for a check-up if they have bad breath.

General information and causes

Bad breath often indicates an underlying problem such as:

  • Dental disease a very common cause of bad breath in cats.
  • Kidney disease - can cause breath to smell like ammonia (similar to bleach).
  • Something stuck in the mouth - if something is stuck in your cat’s mouth or throat (such as a bone), it will start to smell after a while. You may also notice your cat pawing at their mouth or face.
  • Airway infections - often cause bad breath.
  • Diabetes - can cause breath to smell sweet (similar to pear drops or nail polish remover).
  • Diet - certain smelly cat foods can cause bad breath.
  • Gut problems - a gut infection or blockage will often make the breath smell bad, but you are likely to notice other signs such as diarrhoea, vomiting or stomach pain before noticing bad breath.
  • Liver disease - can cause foul, sweet, musty breath.
  • Mouth cancer - cancers in the mouth can become infected and smelly.
Photo of tartar build up on cat's tooth

Tartar build up can cause bad breath in cats.

Other symptoms to look out for

It's important to tell your vet about any other symptoms you have noticed, such as:

When to contact your vet

Bad breath is not normal, even in an older cat. Contact your vet if your cat has bad breath. Your vet will be able to fully, and safely examine your cat’s mouth, which may not be easy for you to do at home.

Consider taking out cat insurance as soon as you bring your cat home, before any signs of illness start. This will give you peace of mind that you have some financial support if they ever become unwell. 

Published: June 2020

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