5 Things to Know About Halitosis in Cats and Dogs

Breath that smells this bad is usually the result of a bacterial infection, which happens when tissue is damaged and bacteria invade.

By: quinn.anya
The most obvious sign of halitosis in a cat is — you guessed it — bad breath. But we’re talking really bad breath here. By: quinn.anya

The word “halitosis” refers to bad breath, but this is about much more than fishy breath — this is an offensive smell caused by disease.

For example, I have known a dog whose breath was so bad that his human was driven from the room whenever the dog entered. Even worse is the affectionate dog with offensive breath who tries to lick you!

The bad smell is usually the result of a bacterial infection that happens when tissue is damaged and bacteria invade.


Although halitosis can happen because of general disease (i.e., kidney failure and diabetes), it most commonly results from mouth problems including dental or gum-health issues, an oral foreign body or cancer affecting the tongue or gums.

In the short term, getting rid of the smell requires antibiotics, but to stop halitosis from returning, vets must look beyond the obvious and find the underlying cause.

The reason for halitosis in cats and dogs is usually an infection in the mouth, but bear in mind that infection usually happens as a result of tissue damage. There are many different causes of halitosis, such as kidney failure and uncontrolled diabetes, causing the body to emit unpleasant-smelling toxins.

Here are 5 things to know about halitosis in cats and dogs:

1. Symptoms of Halitosis in Cats and Dogs

The most obvious symptom of halitosis in a cat is bad breath, the sort that makes you turn away when your cat breathes on you.

But other signs include pain when the cat eats, such that it makes him cautious about eating — which may lead to weight loss.

If the mouth is very inflamed, the cat may drool blood-tinged saliva; he also may be too sore to groom, so his coat becomes unkempt, dull and matted.


When the cat does manage to groom, his coat may start to smell unpleasant because he is spreading smelly saliva all over the fur. Some cats show slightly bizarre signs such as gulping a lot or coughing.

And as for halitosis in dogs — well, most people are all too aware when their dog has halitosis. You may notice it especially if the dog has been left in a room and the smell hits you when you go in.

Dogs often have halitosis because of infection due to another problem; they may drool heavily or have bloodstained saliva. Some dogs have oral pain and find it difficult to pick up or chew food, while others may drink more than usual — because they are trying to get rid of a horrible taste in their mouth.

Causes of Halitosis in Cats and Dogs

Healthy gums and teeth do not smell, and commonly halitosis is caused by infection in the mouth due to other problems.

This list is extensive, but it boils down to things that damage the mucus membrane in the mouth or disease elsewhere in the body that releases toxins (such as kidney disease or diabetes).

While not exhaustive, this list gives an idea of the common problems affecting the mouth:

  • Dental calculus: Soft, sticky foods build up on the teeth and become mineralized by phosphate and calcium in saliva. These hard deposits are called tartar; it pushes on the gums, causing inflammation. Food gets trapped between the teeth, which also causes inflammation and a bad smell.
  • Gingivitis or stomatitis: Inflammation of the gums, usually where the teeth meet the gums, but it can happen anywhere along the gum line, even in the absence of teeth. This is a complex condition with many possible causes such as a suppressed immune system, infection by the Calici virus or dirty teeth that harbor high levels of bacteria. Red, sore gums are more vulnerable to colonization by bacteria, which cause halitosis.
  • Oral cancer: Cancerous lumps can grow rapidly, becoming ulcerated and infected, leading to a bad smell.
  • Tongue lacerations or ulcers: Some cats cut their tongues on tin cans and a nasty infection can result, but happily, these usually respond well to a little TLC, a soft diet and a course of antibiotics.
  • Oral foreign body: These are things that wedge in the mouth and cause damage to the tissue, which becomes infected. The most common oral foreign body in cats is a grass blade. The cat chews grass, but instead of getting cleanly swallowed, the grass blade gets diverted to the back of the throat, where it becomes lodged and traps food. In dogs, the most common of these are pieces of stick or fragments of chewed-up bone.
  • Lip-fold dermatitis. Although not strictly inside the mouth, certain dog breeds, such as Cocker Spaniels, have deep folds of skin around the lower lip. In the warm, moist environment of the mouth, these folds often become infected and can smell very unpleasant.
  • Renal disease and diabetes. When kidneys struggle to function, a toxin called urea builds up in the blood, which can cause oral ulceration and bad breath. Likewise, dogs with uncontrolled diabetes become loaded with ketones, and this sickly, sweet odor is given off on the breath.
Oral foreign bodies, such as stick pieces, could damage a dog’s mouth tissue, infect it and lead to halitosis. By: fakeplasticalice

3. Diagnosis of Halitosis in Cats and Dogs

The cause of bad breath can usually be identified by a thorough inspection of the mouth. After all, you only have to sniff, but the trick is to identify the reason underlying the halitosis.

The first step is a really good look inside the dog or cat’s mouth, checking for tartar buildup, oral ulceration, gingivitis, cancers and objects in the mouth such as sticks or bones. In cases of abnormal tissue in the mouth, a biopsy can give a definitive diagnosis.

However, if the mouth is very painful, a general anesthetic may be necessary to allow a full oral exam, especially right to the back of the throat.

An anesthetic has the added advantage of enabling further investigation at the same time as the exam, such as dental X-rays or a biopsy of any suspicious lumps and bumps should they be indicated.

If disease elsewhere in the body is suspected, then blood tests can identify problems such as kidney failure or diabetes.

4. Treating Halitosis in Cats and Dogs

Treatment for bad breath involves seeking out the infection and correcting the underlying problem.

A course of an antibiotic effective against the common bacteria found in the mouth helps get rid of the smell.

However, a thorough investigation may reveal an underlying problem that needs remediation, such as removing grass blades from the back of the throat, cleaning teeth or instigating treatments for gingivitis or stomatitis.


For more about bad breath in pets, check out the video below:

5. Preventing Halitosis in Cats and Dogs

One of the most common reasons for halitosis is dirty teeth and dental calculus. This is entirely preventable with regular teeth cleaning.

Therefore, good oral hygiene plays an important role in decreasing the chances of dental disease and gingivitis.

The gold standard is daily tooth brushing, but if your cat is not keen on this idea, try feeding a little kibble with teeth-cleaning properties. For dogs, dental chews or dry diets with a teeth cleaning action go some way to slowing down the deposition of tartar.


  • Small Animal Clinical Oncology. Withrow & MacEwen. Publisher: WB Saunders. 2nd edition.
  • Textbook of Feline Medicine. Publisher: Pergamon Press.
  • “Periodontal disease and diet in domestic pets.” Gorrel, 1998. J Nutr., 128: 2712S–2714S.
  • Veterinary Dentistry. Steven Holmstrom, DVM. Publisher: Saunders.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 17, 2018.


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