Why Does My Cat’s Breath Smell? · The Wildest

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Why Does My Cat’s Breath Smell?

Oof, that is bad

Woman playing with her orange cat.
Eloisa Ramos / Stocksy

Have you ever been cuddling with your cat, only to be hit by a wave of unpleasant breath? While occasional bad breath is normal, a persistent foul odour can be a sign of dental problems or other feline health issues that require attention.

What causes bad breath in cats?

Cats are generally pretty good at keeping themselves clean and relatively odourless. Apart from litter box hassles, cats are typically considered tidy and odour-free. But sometimes bad odours can leave you asking, “why does my cat’s breath smell like fish?” Bad kitty breath can ruin a cat’s pristine reputation. Here are some reasons why your cat’s mouth may smell a little ‘off’.

Periodontal disease

Periodontal disease is inflammation of the tissues that support the teeth. It is the most common oral disease in cats. Plaque that accumulates on the teeth can cause inflammation of the gums (gingivitis). Without treatment, bacteria will continue to infiltrate the tissue surrounding the teeth, leading to inflammation and odour. 

Other oral issues

Outside of periodontal disease, there are other issues that can cause oral inflammation, ulceration, infection, and bad odour. Cats can develop bad breath from

  • Stomatitis (inflammation of the soft tissue in the mouth)

  • Electric shock from chewing on electrical cords

  • Ingesting caustic chemicals

  • Oronasal fistulas (abnormal connections between the nose and mouth)

  • Oral cancer

Kidney disease

One of the kidneys’ main jobs is to remove waste and toxins from the blood. When the kidneys aren’t functioning properly, those waste products can build up in the bloodstream, a condition called uraemia. One of the symptoms of uraemia in cats is ‘uraemic breath’ – an ammonia-like odour to a cat’s breath. 


Diabetes mellitus is a disease in which blood sugar levels are too high due to insulin resistance or insufficient insulin production. When diabetes is unregulated, a cat’s body can start to break down fat for energy because it’s not able to use glucose. This fat breakdown leads to ketone formation. High levels of ketones can cause a cat’s breath to have an unusual sweet smell, sometimes called ‘ketotic breath’.  Because not everyone has the ability to smell ketones, sniffing for ketotic breath isn’t a good screening test for unregulated diabetes.  

Dietary issues

A cat’s eating habits can impact how their breath smells. If a cat is eating stinky stuff, like dead carcasses and faeces, that’s bound to lead to a bit of bad breath.  Also, cats that eat wet food can have morsels of food that stick around on the teeth and tongue after meal time, contributing to fishy breath odour. 

Respiratory issues

Excessive mucus production from the nose can lead to an overall unpleasant odour coming from a cat’s face. If the mucus is due to infection, nasal tumours or nasal foreign bodies, this is more likely to cause cat bad breath and sneezing. 

Gastrointestinal disease

Gastrointestinal diseases, like megaesophagus, can cause stinky cat breath. Megaesophagus occurs when a cat’s oesophagus is flaccid and dilated, making it difficult for food to be pushed down into the stomach. Food tends to sit in the oesophagus or be regurgitated back into the mouth, and will start to ferment and smell. Cats with gastrointestinal obstruction can also have foul-smelling vomit and breath. 

How to treat bad breath in cats


Teeth can start to accumulate plaque within a day, so regular brushing can remove it and stop gingivitis from progressing to periodontal disease. Think brushing a cat’s teeth sounds impossible? Check out this guide. Be sure to use cat-safe toothpaste. 

Dental treats and chews

Cat parents can also opt for dental treats and chews to help control bad breath. While crunching on these treats, cats get the added benefit of plaque and tartar removal. Be sure to keep treats to less than 10 percent of your cat’s daily calorie intake. 

Water additives 

Water additives can help reduce plaque and bacteria in cats’ mouths, leading to fresher breath. When introducing a dental additive to your cat’s water, monitor closely to ensure that your cat is still drinking well. If your cat is completely put off and refusing to drink, opt for a different flavour or skip additives all together.

When searching for water additives or dental treats, start with products approved by the Veterinary Oral Health Council (VOHC), a group of veterinary dental health professionals who look into the efficacy of pet dental products. 

Balanced diet

Sometimes cats eat nasty things (like poo and cat litter) because of behavioural issues, but sometimes cats do this because they have nutritional deficiencies. Make sure your cat is eating a complete and balanced diet formulated specifically for cats. 

When to seek veterinary attention

Your cat’s mouth isn’t always going to smell squeaky clean. A little odour is normal, especially after meal time. But bad breath should not be ignored, especially if it is consistent, appears suddenly or accompanies other symptoms. Concerning symptoms include:

  • Anorexia

  • Pain when eating

  • Dropping food

  • Facial swelling

  • Nasal discharge

  • Excessive drooling

  • Vomiting

  • Lethargy

When investigating your cat’s halitosis, your vet will start with a medical history and a physical exam. Be sure to report any changes in appetite, water intake or litter box habits. If it’s clear that your cat has dental disease, your vet will want to perform a full oral exam. This may require sedation depending on your kitty’s temperament and discomfort level. Dental disease treatment often involves pre-anaesthetic blood work, dental radiographs (gotta check out those tooth roots), antibiotics and dental care under general anaesthesia. 

If your cat’s bad breath is not obviously dental in origin, blood work and a urinalysis can be performed to look for systemic issues like kidney disease or diabetes. Radiographs can help rule out gastrointestinal disorders like megaesophagus or obstruction. If the nasal cavity is suspected to be the source of the smell, imaging like rhinoscopy can directly evaluate the nasal cavity for foreign bodies, tumours, or abnormal tissue. 

As always, prevention is easier than treatment. Regular checkups and dental care can help prevent health issues, saving cats from discomfort and cat parents from kitty stank breath.

Frequently asked questions

How do you treat bad breath in cats? 

Bad breath in cats should be evaluated by a vet to determine the cause and best treatment. At home, cat parents can combat bad cat breath with tooth brushing (with cat-safe toothpaste), dental treats, water additives and a well-balanced diet. 

What is the best cat-bad-breath remedy? 

The best cat bad breath remedy is to seek veterinary advice. Your cat may need a professional cleaning to get rid of bad breath. For at-home care, the best remedy is the one you’ll stick with and your cat will tolerate. 

Why does my cat chew on everything?

Cats may chew for many reasons, including curiosity, boredom and gastrointestinal issues. If your cat is a chewer, eliminate access to toxic plants, electrical cords and objects that can be accidentally swallowed. And talk to your vet. 


Dr. Bartley Harrison holding his dog

Dr. Bartley Harrison, DVM

Dr. Bartley Harrison, DVM is a small animal veterinarian based in North Carolina who has practiced emergency medicine since graduating from the Texas A&M College of Veterinary Medicine. His primary interest areas include pain management, cardiology, and the treatment of shock.

He is a member of the Veterinary Emergency and Critical Care Society, American Veterinary Medical Association, and American Medical Writers Association. In addition to his clinical work, he writes pet health articles to help provide accurate information for both new and experienced pet parents. When he’s not working, he enjoys cooking, traveling, reading, and going on adventures with his dog.

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