What Causes Bad Dog Breath? A Vet Explains

Quick takeaway: Bad dog breath is called halitosis. It can develop at any age, but is more common in older dogs who do not get regular dental care, and in puppies when adult teeth start to grow in. Bad dog breath is caused by a variety of factors, including periodontal disease, fractured teeth, inconsistent dental care, and several different health conditions where a sour or fishy smell to the breath is a common symptom. If your dog has bad breath, here are some of the possible reasons why.

Recognizing Bad Dog Breath & The Potential Causes 

You might notice your dog has bad breath when they’re licking or breathing in your face. Another way you might recognize that something is off with your dog’s breath is if their chew toys have become rather stinky. In some cases, particularly with advanced dental disease, you can smell your dog’s bad breath from across the room. 

Bad breath in dogs is called halitosis. Halitosis in dogs can develop at any age, though we often think of it as happening in older dogs who do not get regular dental care. 

In puppies, bad breath often develops when the adult teeth start to grow in. Puppy pet parents sometimes report that their dog’s breath smells like metal. This is because of gum inflammation and bleeding that occur as puppy teeth fall out and adult teeth come in. Puppy bad breath can also be associated with eating items they shouldn’t, like dog poop. 

Bad breath in dogs can be described as fishy, sweet, metallic, rotten, or smelling like sulfur. We’ll get into what causes these different smells as we talk about the causes of bad breath. 

Why Does My Dog Have Bad Breath? 8 Possible Causes 

Bad dog breath can have a range of causes, including what your dog eats, oral health issues, and systemic diseases. The following are seven causes of bad breath in dogs: 

Bad oral hygiene

Before you start to panic that something is wrong with your furry friend, start with the most common reason for bad breath – poor oral hygiene. This could be caused by a poor oral hygiene routine.

Unfortunately for our four-legged pals, they can experience a build-up of tartar and plaque, just like us humans, resulting in the overdevelopment of bacteria which causes smelly breath.

If you do not regularly brush your dog’s teeth or provide a chew toy/food to wear away the tartar deposits, this could be the cause of your bad breath problem and if neglected, it may result in your pup dealing with more serious complications, for which you would have to consult your vet.

Poor diet

Sometimes the cause of the bad breath is simply down to what your pups have decided to put into their stomachs. Dogs may choose to eat a lot of nasty things they shouldn’t, either burying themselves in the garbage or finding something disgusting whilst on your walk!

We have all found our furry friends chewing on a questionable object and let’s not forget the strange behavior of extremely enjoying consuming other animals’ poop! This unsupervised, unhygienic scavenging could be the reason your pooch is producing a smelly pong. If you know you have a poop-eating dog in your family, they could develop a condition called coprophagia, resulting in the bad breath that you may have noticed.

There are many ways to address this behavior such as by making sure their diet is not deficient in any nutrients and providing enough enrichment throughout the day so their boredom and anxiety levels are very low.

Periodontal Disease Causes Bad Dog Breath

Periodontal disease, which refers to infection and inflammation of the tissues around the teeth, is the most common cause of dog halitosis. According to Cornell University’s College of Veterinary Medicine, over 80% of dogs that are 3 years of age or older have periodontal disease. 

Within a few hours of eating, a dog begins to develop plaque on their teeth, including beneath the gumline. Over time, plaque hardens into tartar. Bacteria that are associated with plaque and tartar infiltrate the tissues around the teeth, causing gum inflammation (gingivitis). As the condition worsens, pockets will begin to develop around the teeth. Eventually, the dog can start having teeth fall out. 

The bad breath of periodontal disease is associated with the bacteria causing decay of the tissues around the teeth. These bacteria produce sulfur compounds, so the smell is often described as smelling like sulfur or garbage. If there is bleeding in the mouth, a metallic odor may also be noticed. 

Fractured Teeth Can Lead To Stinky Breath in Dogs

Fractured teeth, especially if the tooth is fractured into the pulp canal (where the blood vessels and nerves are), can contribute to dog bad breath. Bacteria can infiltrate within the tooth and cause infection of the tooth and surrounding tissue. Much like periodontal disease, bad breath associated with fractured teeth often has a sulfur smell. In some cases, bleeding will also contribute a metallic component to the stinky breath. 

Oral Tumors Can Cause A Metallic Smell

Not all oral tumors will cause bad breath, but if the tumor bleeds, you may notice a metallic smell to your dog’s breath. Some oral tumors can be aggressive, such as melanoma, so it’s important to get any growths you notice in your dog’s mouth examined by a veterinarian. 

Something Your Dog Ate or Licked Can Lead To Stinky Breath

Sometimes, bad breath simply comes down to what your dog ate or licked. If your dog’s breath smells like garbage, did they recently get in the trashcan? If it smells like poop, is your pup sometimes partaking in coprophagia (eating feces) or getting into the cat’s litter box? 

Your dog’s normal diet also contributes to their breath. Dogs who eat a fish-based diet or take fish oil supplements are sometimes noted to have fishy dog breath, for example. People sometimes associate a fishy odor with a dog’s anal glands, as well. If your dog is having issues with their anal sacs, they may lick at them and develop stinky breath.  

Diabetes Can Cause Sweet-Smelling Dog Breath

Sometimes bad breath in dogs can be a sign of illness. Dogs who have unmanaged diabetes can develop a sweet or acetone smell to their breath. Without proper insulin, the body begins to break down fat into ketones for energy. The dog develops diabetic ketoacidosis (DKA), which requires emergency treatment. 

If your dog is experiencing excessive thirst and urination, losing weight, and having appetite changes, make sure to get diabetes ruled out. 

Kidney Disease Can Cause An Ammonia Smell To Your Dog’s Breath

Dogs with kidney disease often have an ammonia smell to their breath. This is because a dog with kidney disease has a build-up of toxins in their blood, called uremia. In some cases, dogs with kidney disease will also have metallic breath if they have sores in their mouth. 

There is some crossover in the signs of kidney disease and diabetes in dogs. If your dog is excessively thirsty and urinating, losing weight, has a decreased appetite, and/or is vomiting, it’s important for your veterinarian to rule out kidney disease.  

Liver Disease Can Lead To Rotten-Smelling Dog Breath

Dogs with liver disease will have foul breath that is sometimes described as smelling rotten or like death. This occurs because the liver is no longer able to adequately filter toxins in the blood. Pets with liver disease sometimes have metallic breath if they are experiencing bleeding abnormalities or stomach ulcers. 

Get your pet examined by a veterinarian right away if you’re noticing vomiting, diarrhea, lethargy, bleeding issues, and/or yellowing of the eyes, gums, or skin (jaundice). 

Tips for Preventing Bad Breath in Dogs 

While there are things you can do to combat bad breath after it develops, it’s preferable to prevent bad breath from developing in the first place! 

When it comes to preventing oral causes of bad breath like periodontal disease, consider the following: 

• Brush your dog’s teeth with pet-safe toothpaste at least three times weekly. Ideally, you would do this once daily. 
• Consider prescription diets that scrub at the teeth. 
• Give your dog dental toys that scrub at the teeth. 
• Visit your veterinarian for oral examinations and professional cleanings. 

While regular dental care is important, you can also consider the following tips for preventing other causes of bad breath in dogs: 

1. Use latching trashcans to keep your pet out of the garbage. 
2. Pick up fecal matter so it cannot be consumed.
3. Seek veterinary attention if your dog is scooting or licking at their behind. 
4. Keep toxic substances like antifreeze or grapes out of reach. 
5. Regularly visit the veterinarian to monitor your dog’s overall health. 

If you have questions or concerns about your dog’s breath, it’s always best to consult with a veterinarian. 

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