This Is Why Your Dog’s Breath Smells So Bad, and What to Do About It

dog breath
© Kirill Linnik/

Written by Sharon Parry

Updated: October 4, 2022

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Dog kisses are the most adorable thing – unless your pooch has stinky breath (halitosis) and you are left wondering why does my dog’s breath smell? Is this normal or is it a sign that something is up with your four-legged friend?

The most common cause of bad breath in dogs is gum and dental disease but it can also be caused by foreign bodies in the mouth and intestines. Smelly breath is also one of the symptoms of diabetes, kidney disease and liver disease.

Whys Does My Dog’s Breath Smell?

Dog breath is often dismissed as normal but there is nearly always a reason behind it. Here are the most common causes of bad breath in dogs.

Eating Something Disgusting

Unfortunately, dogs are attracted to stinky things! It probably has something to do with their history as scavengers when they would hunt out carcasses of dead animals. Dogs also like to eat things that we humans find disgusting. This includes fox poop, cat poop and even their own poop! This is called coprophagia. Inevitably, this is going to make their breath smell unpleasant.  

Foreign Bodies Stuck in Mouth or Intestines

Most dogs love to chew things. Unfortunately, there are plenty of objects that can get stuck in their mouth and between their teeth. Fabric toys can get shredded and fibers can easily get lodged between teeth. Sticks can easily get lodged across the roof of a dog’s mouth. It has even been known for this to happen with chew toys. Other materials, including string, can get looped around the tongue. If this is the cause of the bad breath, your dog will also avoid eating and may vomit.

Also, if a dog has swallowed a foreign object, such as a sock or small toy, and this is lodged in their intestines it can cause foul breath.

Eating Something Toxic

Some dogs like to eat scraps and objects from the environment more than others. They can ingest anything from cigarettes to toxic plants. All of them can make your dog’s breath smell unpleasant. It may smell like the item they have eaten e.g. like cigarettes. Or, it may smell because their body is reacting to it.

If you know that your dog has eaten something toxic in the environment, you should speak to your vet right away.

cigarette butts on the ground

Your dog can eat all manner of material he finds on the ground, including discarded cigarette butts.


Gum Disease and Dental Disease

Periodontal disease is by far the most common cause of bad breath in dogs. It is caused by an overgrowth of bacteria in the mouth causing a build-up of plaque which is called dental calculus. This, in turn, leads to a buildup of tartar and eventually chronic inflammation of the gums. Dogs with crowded or misaligned teeth are at the highest risk. In the early stages, it is invisible but soon you will notice that your dog’s gums are red and swollen and bleed quite readily. You will also notice the bad breath! This is a progressive condition which means that if it is not treated, it will spread to other parts of the gums and even to the bones. As the plaque and tartar build up, they push the gums away from the teeth creating pockets where even more debris can collect and more bacteria can multiply The build-up of tartar, and the food debris that gets stuck in it is what causes the unpleasant smell. In extreme cases, even hair can get stuck in it and there may be pus in the gums.

Sadly, periodontal disease is often not diagnosed before it is in the advanced stages when it is harder to treat. It can lead to tooth decay, receding gums and lost teeth. In extreme cases, there can be eye problems and damage to other organs. Prevention is always better than cure!

Rotting teeth can also give your dog bad breath. Your pooch may also be in pain and refuse to eat as well as pawing at their mouth.


Diabetes in dogs causes them to have a fruity and sweet smell in their mouths. Other signs of diabetes include a loss of weight, increased thirst, doing a pee more often and changes in appetite.

In dogs with diabetes, the body fat is broken down and this produces substances called ketones which have a sweet smell (acetone) and can be detected in the breath.

This is a distinctive smell that is very different to the smell of dental disease.

Kidney Disease

Kidneys filter waste products out of the blood. When they are not working properly, these waste products build up and blood levels rise. The main waste product that should be removed by the kidneys is called urea and when this builds in the body, it can make their breath smell. The odor is like ammonia and you may think that your dog has been licking urine which has a similar odor. However, this is a sign that the kidneys are not working properly.

When there is too much urea in the blood it is called uremia and this can make your dog very ill. Dogs with kidney disease also have a loss of appetite, weakness, lethargy and ulcers in the mouth.

With the right treatment, dogs can live with chronic kidney disease but it is important to consult your vet promptly.

Liver Disease

Liver disease is a serious medical condition that is usually caused by infections, toxins or chemicals. The liver plays a vital role in breaking down and forming chemicals that are essential for the body to function. Therefore, serious liver disease can result in death.

There are several signs of liver disease in dogs and bad breath is one of them. This is because toxins are building up in the bloodstream. The other tell-tale sign is jaundice where the skin and whites of the eyes look yellow. A dog with liver failure will also probably have a poor appetite, vomiting and they may lose weight.

Liver disease requires prompt treatment so you need to get your dog to a vet right away.

Tumors in the Mouth

Dogs can get cancerous growths in their mouths – oral tumors. Around 6% of all canine tumors occur in the mouth and there are lots of different types including melanoma, squamous cell carcinoma, sarcoma, ameloblastoma and peripheral odontogenic fibroma.  They are more common in older dogs and the outcome is very variable.

As the tumor grows, it can become infected and some of the flesh inside the mouth dies off which has a very unpleasant odor. All unusual bumps and lumps need to be checked out by your vet.

Problems With the Diet

If you don’t feed your dog a premium commercial dog food, they can have deficiencies in their diet. This can be a problem with diets that you prepare yourself – raw and home-cooked diets. They can lead to an imbalance of bacteria and there can be an overgrowth of bacteria such as salmonella that can cause bad breath.

If you are feeding your dog a diet that you are preparing yourself and their breath has started to smell, get some advice from your vet or an animal nutritionist.

raw dog food

Dog food you prepare yourself, especially if raw, may contain salmonella and other bacteria that can give your dog bad breath.


How to Tackle Bad Breath in Dogs

All of the medical conditions listed here require treatment by a vet. So, if your dog also has other symptoms or you can see anything obvious inside your dog’s mouth that is causing the problem, consult your veterinary practice.

Treatments vary according to the underlying cause. Your dog may need medication, surgery, therapy or a special medical diet.

However, by far the most common cause of bad breath in dogs is plaque, tartar, and periodontal disease. Your dog may need a general anesthetic so that your vet can thoroughly clean the teeth to remove plaque. They will also remove any rotten teeth.

Preventing Bad Breath in Dogs

There is a lot that you can do to prevent your dog’s breath getting smelly in the first place. A lot of it comes down to controlling what your dog eats and good dental hygiene.

Control What Your Dog Eats

This starts with their diet. Provide your dog with a balanced diet that contains all the nutrients that they need. Some studies have shown that large kibble is better for dental health than soft food. Also, dental chews can help to scrape off plaque. The Veterinary Oral Health Council has plenty of further advice on canine oral health.

It will also help a lot if you can prevent unauthorized snacking! This means that you will need to store food that you don’t want your dog to eat out of their reach. Use a trash can with a secure lid and purchase a dog-proof cat litter box if you have to. If your dog has a habit of eating poop, roadkill and garbage when you are out on walks, invest in a head halter collar to control the position of their head.

Protect Your Dog’s Dental Health

The most effective way to prevent smelly breath is to look after your dog’s dental health. The most effective way to do this is to brush their teeth using a special dog toothpaste. It can take a while to train your dog to allow you to do this but it is worth it. Never use human toothpaste though because it is toxic for dogs. Most dog toothpastes have a flavor that dogs will enjoy.

It is also possible to get products that you add to your dog’s water that will both help with dental hygiene and tackle bad breath.

Most dogs naturally love to chew and you can use this to your advantage. Get your dog a range of chew toys with different types of textures. They will scrape off the plaque and stop tartar from building up as well as keeping your dog amused. Make sure that the toy you choose is suitable for your dog’s age and size because inappropriate chew toys can get stuck in the mouth or can present a choking hazard.

groomer brushing dog teeth

One of the best ways to eliminate or prevent bad breath in your pooch is to periodically brush their teeth.

©Aquarius Studio/

Look After Your Dog’s General Health

Many of the diseases that lead to bad breath can be prevented by looking after your dog’s general health. A good diet and exercise are the two things that can help to prevent your dog from developing disorders such as diabetes. Also, take your dog for all of their recommended vaccinations and for regular health checks with their vet.

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About the Author

Dr Sharon Parry is a writer at A-Z animals where her primary focus is on dogs, animal behavior, and research. Sharon holds a PhD from Leeds University, UK which she earned in 1998 and has been working as a science writer for the last 15 years. A resident of Wales, UK, Sharon loves taking care of her spaniel named Dexter and hiking around coastlines and mountains.

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