My Cat Has Bad Breath Smells Like Fish

cat's breath stinks

Despite a reputation for independence, cats have no problem getting right up and close when they want your attention. That includes waking you up from a calm, deep sleep with a whiff of bad breath aimed directly at your face.

Constant bad breath could be a sign of an underlying health issue. So when is bad too bad, and what are the most typical causes of bad breath in cats? 

Read on to learn more about gingivitis and other common conditions and how you can help improve your cat’s oral hygiene.

The Most Common Causes of Bad Cat Breath

Cat food can often cause bad breath. Sometimes pieces of wet and soft cat food can get stuck between a cat’s teeth. This tends not to happen so much with dry food. Even a small piece of tuna caught between the teeth can lead to bad breath.

Ulcers, sores, abscesses, and teething in kittens may also be at play. Gingivitis is an inflammation of the gums. It happens when bacteria build up in your cat’s mouth over time and form a sticky layer known as plaque on the surface of the teeth. Gingivitis can be uncomfortable and may lead to bad breath in cats.

Gingivitis is a mild form of periodontal disease. Left untreated, the bacteria in dental plaque will start to irritate the gum tissue even further, potentially leading to an infection in the bone around the teeth. 

Within a short space of time, plaque can mineralize and toughen to form tartar – the visibly hard, brown material you can see on dirty teeth. This creates an ideal surface for yet more plaque to build up. Periodontal disease can result in bleeding gums, tooth loss, pain, and other severe issues which can require surgery to control. Other symptoms can include:

  • Redness in the mouth and gums
  • Behavioral changes
  • Disinterest in eating and a loss of appetite

Gut and Airway Infections 

A gut infection or blockage may make a cat’s breath smell bad. It’s likely you will see other symptoms first like diarrhea, vomiting, or stomach pain. Airway infections too can cause a cat’s breath to smell.

Cat insurance from From Dog insurance from Coverage Contribution Own risk
petsecur logo €8.46 €12.11 €3.250 — €6.000 10% — 50% €0 — €150
per year
ohra logo €14.05 €17.77 €3.000 — €6.000 20% €30 — €50
per year
figopet logo €12.16 €17.42 €3.000 — €5.000 20% — 50% €0 — €250
per year
InShared logo €13.27 €20,14 €3.000 — €6.000 20% none View
Unive logo €13.86 €14.67 €2.500 — €5.000 20% none View
aegon logo €10.56 €13.14 €3.500 25% €25
per claim

Lymphocytic Plasmacytic Stomatitis

This is another cause of bad breath in cats. There’s often a link between it and calicivirus, feline immunodeficiency virus, feline leukemia virus, and other infections.

It causes severe inflammation of the mouth along with an unpleasant smell and often extreme pain. A cat’s gums can become sore, swollen, and bleeding. It makes it painful for a cat to even open their mouth.

Treatment tends to involve cleaning along with the removal of some or all the teeth as well as a course of antibiotics. Because there can be an association with the calicivirus, it’s important for cats to receive the vaccine that protects them from this disease. Always check to be sure you are up-to-date with your pet’s vaccines.

Oral Cancers

Oral cancers can also cause foul mouth odors. As a tumor gets bigger, it can become infected and cause bad breath. The prognosis for a cat with oral cancer is not generally good.

Kidney Disease

If your cat’s breath resembles the smell of urine or ammonia, it could be a sign of kidney disease. This is not uncommon in older cats aged 8 or over. As well as having bad breath, your cat may become lethargic, experience weight loss, drink more water, and urinate more often and in greater quantities.


If your cat’s breath has a fruity smell, it may be a sign of diabetes, particularly if your pet is also drinking more water than usual, urinating more often, and losing weight despite always appearing hungry.

Liver Disease

As well as foul-smelling breath, you may see a yellowing of the eyes, ears, and gums in a cat with liver disease. They may also become lethargic, have little appetite, suffer from bouts of vomiting or diarrhea, and drink and urinate more than normal. 

How Can You Treat and Prevent Bad Cat Breath?

Ensuring good oral hygiene is the best option to try to stop periodontal disease in its tracks. Brushing your cat’s teeth every day would be the best idea. Although not easy because of the resistance many cats will put up, it is often possible with patience and perseverance. 

Experts recommend that you train your cat to be receptive to teeth cleaning very slowly. Start by getting your cat used to you lifting up their lip, for example. Then introduce the brush in the mouth and eventually the act of brushing. Always use toothpaste specially created for cats.

When brushing the teeth is impossible, wipe your cat’s teeth with dry gauze to help take away some of the plaque. Dental diets can also reduce plaque build-up and freshen up the breath. You should talk to your vet about the best available products to feed your cat.

A Professional Clean

Dental treats can help to reduce plaque tartar – although often less effective than dental dry food. Again, talk to your vet to check the validity of any marketing claims.

You should also consider having your cat’s teeth cleaned professionally at a veterinary practice. Once under anesthetic, your vet will remove plaque and tartar from your cat’s teeth. They can also take x-rays and check for any diseased teeth that may need to undergo extraction.

When Should You Contact the Vet?

There are sometimes clear links between oral hygiene, the smell of a cat’s breath, and other more serious medical conditions. Because of this, you should keep a close eye on your cat’s teeth and gums. 

If you notice changes to your cat’s breath, teeth, or gums that are unlikely to relate solely to what you are feeding them, then it is always wise to seek the advice of a vet. Bad breath in cats is not normal so it’s best to err on the side of caution and seek advice.
We have a team of experts on hand to help. Book a consultation right now with one of our experienced vets right now. We’re also able to offer a range of pet insurance products to help ensure your cat always gets the best treatment available.

Looking for answers for
your furry friend?

Use our automatic Symptom Checker for advice on what to do next.

  • Answer questions about the issue to narrow down options
  • Wide range of symptoms and answers
  • Information on the most common toxic foods and household items
What seems to be the problem?
My dog Lily has vomited
Is there blood in the vomit?
Check Symptoms Now