8 Possible Causes for Your Dog's Bad Breath

Close-up of dog outside, mouth open and eyes closed
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You love your dog, but every time it comes in for a kiss, it knocks you flat. It's almost enough to make you avoid that sweet little face.

So, what's the reason for your pet's horrendous dog breath? Sure, it could be something it ate, but bad breath can also indicate an underlying medical condition that may require veterinary investigation. Here's a look at some of the more common causes for canine halitosis.

Periodontal Disease

Periodontal disease, or gum disease, is the primary cause of bad breath in dogs and the most common health problem affecting adult dogs and cats, according to the American Veterinary Medical Association. Your pet is likely to show early evidence of it by the time it reaches three years old. Gum disease is caused by bacteria in the mouth forming plaque that sticks to the surface of the teeth. That plaque then hardens into tartar and can become especially problematic if it spreads below the gumline. In addition to the possibility of tooth loss, if the disease progresses enough and bacteria enters the bloodstream, it can cause damage to your dog's heart, liver, and kidneys, according to the American Veterinary Dental College.

You can try to prevent gum disease by brushing your dog's teeth daily — or at least several times a week — using doggy toothpaste and a toothbrush. You may want to ask your vet about other preventive measures, such as rinses or special chew toys, that may help ward off periodontal disease. Your vet may also want you to bring your dog in on occasion for professional cleanings, in which the dog will be sedated while the plaque and tartar is scraped away and teeth are polished.


Beagle puppy chewing ring dog toy
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Although puppies usually have the sweetest breath, it can occasionally get a little rank. This is usually caused by the mild bleeding that may naturally occur when your dog is chewing on toys. On the contrary, dogs tend not to accumulate enough mouth bacteria to create a foul odor until adulthood, so if you notice persistent bad breath in your puppy, Australia's largest pet care company, Greencross Vets, says it could be a sign of infection.


Dogs with diabetes can have breath that smells distinctly like acetone, the compound commonly used in nail polish remover. This is because acetone is a type of ketone, and diabetics have high levels of ketones in their blood, which makes it more acidic. These ketones can also sometimes smell especially sweet or fruity.

If your pet has diabetes, you may notice that it's drinking and urinating more, or possibly even having accidents in the house. Other symptoms include sudden weight loss and an increased appetite, as well as behavior changes, like irritability or excessive sleeping. If things seem abnormal, you should schedule blood and urine tests with your vet.

Liver Problems

If your dog has exceptionally strong, foul breath combined with vomiting, appetite loss, or yellowing gums and corneas, that could be a sign of liver disease. The American Kennel Club says this smell is distinctly different than the smell caused by periodontal disease — bad breath caused by liver disease smells musty or like a dead animal, whereas bad breath caused by periodontal disease smells more sulfuric. You should visit the vet immediately if you suspect your dog has liver disease, as it can be life-threatening.

Kidney Disease

Dog breath that smells like urine or ammonia could be a sign of kidney disease, according to the American Kennel Club. In the medical world, this smell is described as "uremic" and is caused by toxins — such as ammonia and nitrogen — that can build up in a dog's body when its kidneys fail. Other symptoms include changes in weight and appetite, drinking or urinating more or less, listlessness, and depression.

Sinusitis or Rhinitis

When you get a cold or sinus infection, you may have to breathe through your mouth, which inevitably causes it to dry out and makes you have bad breath. The same thing can happen to your pet when its upper respiratory tract or sinuses are inflamed. In addition to sinusitis and rhinitis (inflammation of the mucous membrane), other causes of an obstructed respiratory tract include nasal infections and tumors.

Gastrointestinal Issues

Although it's less common, stomach and digestive problems — such as megaesophagus, the enlargement or stretching of the esophageal tube, which goes from the throat to the stomach — is another cause of oral odors, the Veterinary Centers of America says. Talk to your vet if you notice any other unusual symptoms, particularly changes in appetite, nausea or vomiting, or changes in stool.

Icky Diet

Every once in a while, your dog may decide to eat something that smells horrific. Maybe it's cat poop, their own poop, or something from the trash, but the results (other than an upset stomach) can be incredibly foul breath. This is usually temporary, unless your pet has an insatiable appetite for gross things. In that case, you may want to lock away the litter box and the garbage can.

How to Get Rid of Your Dog’s Bad Breath

Once you've paid a visit to the vet and eliminated the possibility of your dog having a serious medical condition, you can begin tackling its foul-smelling — albeit harmless — breath. Here's how.

  • Brush its teeth: The simplest and potentially most effective way to combat bad breath (both for dogs and humans)? Give those teeth a thorough brushing. The Veterinary Centers of America recommends brushing a dog's teeth twice daily (or several times per week, minimum).
  • Introduce chew toys: Rubbery chew toys, especially, can help scrape tartar accumulation off your dog's teeth when it chews on them.
  • Clean food and water dishes: Your dog's food bowls can harbor a lot of nasty bacteria, which can in turn get into the mouth and cause bad breath. They should be cleaned after every meal or at least once per day.
  • Coconut oil: This trendy superfood is good for dogs, too. It will clean out their gastrointestinal tracts in case there's something in the belly that's causing the mouth to smell. Check with your vet about appropriate dosages for your dog. Remember, coconut oil is high in fat, so you should monitor your dog's weight.
  • Fruits and veggies: Certain foods, such as carrots and strawberries, are dog-safe and good for dogs' teeth. However, you should only feed your dog these snacks in moderation. Check with your vet to find out an appropriate serving size.

Why Pets Matter to Treehugger

At Treehugger, we are advocates of animal welfare, including our pets and other domestic animals. The better we understand our dogs, the better we can support and protect their wellbeing. We hope our readers will adopt rescue pets instead of shopping from breeders or pet stores, and will also consider supporting local animal shelters.

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