Dog Bad Breath? What Vets Say About Causes and Fixes

You might be used to your dog’s breath having a bit of a “doggy” scent, but if it’s starting to turn your head (and not in a good way), it’s time to take notice.

Bad breath can be one of the first signs of dental disease, and it’s often linked to problems that go beyond the mouth. From plaque build-up to kidney issues, this guide will help you understand what’s normal, what’s not, and what to do next.

With the right care, fresher breath, and a healthier dog is within reach.

While most people associate bad breath with poor dental hygiene, in dogs it can be a warning sign of underlying disease. Dental infections, oral abscesses, kidney or liver dysfunction, and metabolic conditions can all change the smell of your dog’s breath. Left untreated, these issues can lead to pain, tooth loss, and even spread bacteria to major organs.

For a deeper dive into oral health, check out our guide on creating a dog dental care routine to support healthier teeth and gums.

It’s normal for dogs to have a mild “doggy” scent, especially after a treat or chewing on a toy. But breath that smells rotten, sweet, or like ammonia is a concern.

Here are some of the most common causes of persistent bad breath in dogs:

• Dental disease: plaque, tartar, gingivitis, and periodontal decay
• Diet & chewing: low-quality food, table scraps, lack of abrasive chewing
• Oral infections: abscesses or infected gums and roots
• Foreign objects: sticks, bones, or string stuck in the mouth
• Metabolic issues: kidney, liver, or diabetic conditions causing distinctive breath odours

Want to take action now? Browse our curated range of dog toothbrushes to start fresh at home, or check out vet-recommended dog dental diets designed to scrub teeth as your dog eats.

Dental problems are by far the most common reason dogs develop bad breath. Plaque hardens into tartar, which pushes under the gum line and harbors bacteria. Over time, this leads to gingivitis and periodontal disease, causing that unmistakable foul odour. In advanced cases, infected tooth roots and bone loss can occur, making the smell even worse — and painful for your dog.

Want to learn more? Our guide to dog dental care covers early red flags to catch problems before they become severe.

Dogs that eat only soft food or receive lots of table scraps often miss out on the natural tooth-cleaning benefits of chewing. Crunching on dry kibble or approved dog dental chews helps mechanically scrape away plaque. Diets high in sticky carbs or sugars can also promote bacterial growth, worsening mouth odour.

If your dog’s diet might be contributing, consider switching to a vet-recommended dental diet or offering daily VOHC-approved dental chews to help control plaque naturally.

Check out our vet-approved guide to the Best Dental Dog Food.

Sometimes the bad smell is due to infection deep under the gum line. Bacteria can invade tiny pockets between the teeth and gums or enter through a cracked tooth, forming painful abscesses. This often produces a particularly foul, rotting smell and requires prompt veterinary care.

Dogs are experts at getting bits of sticks, string, or food wedged between their teeth or under the gum. These foreign bodies rot, irritate the tissue, and breed bacteria — all adding up to a mouth that smells far worse than normal “dog breath.” If your dog is pawing at their face or seems uncomfortable, a vet exam can check for hidden debris.

Not all bad breath starts in the mouth. Kidney disease in your dog can give them breath a metallic or ammonia-like smell, while liver problems sometimes cause an oddly musty odour. Uncontrolled diabetes often produces a sweet, fruity scent. If your dog’s breath changes suddenly along with increased drinking, vomiting, or lethargy, it’s time to call your vet.

Occasional mild dog breath is normal, but certain signs mean you shouldn’t wait. Call your vet promptly if your dog’s bad breath is accompanied by:

• Bleeding from the mouth or gums
• Dropping food or refusing to eat
• Pawing at the face or persistent drooling
• Facial swelling
• Vomiting or sudden weight loss

This way, you can catch serious problems early — and get your dog feeling better (and smelling better) faster.

If tartar is already established, no home care will remove it. Professional dental cleanings under anaesthetic allow your vet to scale below the gum line and polish the teeth, dramatically reducing bacteria and improving breath almost immediately. It’s also the only way to safely check for loose teeth or hidden infections.

Brushing is still the gold standard. Using a dog toothbrush and pet-safe toothpaste just a few times a week can significantly slow plaque buildup. For dogs who resist brushing, dental gels or rinses can also help reduce bacteria.

A high-quality diet supports oral health from the inside out. Dental-specific kibble scrubs teeth with each bite, while low-stick formulas reduce residue that feeds mouth bacteria. Avoid sticky treats or human scraps that linger on teeth.

Adding oral health powders to food or water can reduce harmful bacteria, freshen breath, and support gum health. Probiotics for oral balance are also gaining popularity, helping keep bad breath bacteria in check.

How quickly your dog’s breath improves depends on what’s causing the odour — and how advanced it is.

If the smell is due to minor plaque and you start brushing or switch to a dental diet, you might notice fresher breath in just a couple of weeks. After a professional dental cleaning, most owners notice their dog’s mouth smells dramatically better almost immediately.

Keep in mind: if gum disease was already established, long-term improvements rely on maintaining daily care. That means brushing, offering VOHC-approved dental chews, and sticking to a quality diet to keep that clean mouth going strong.

Yes — while most bad breath comes from dental problems, certain smells point to internal diseases.

• Kidney disease often makes breath smell like ammonia or urine, due to waste products building up in the bloodstream.
• Liver issues can create a musty, foul scent, sometimes paired with yellow gums or eyes.
• Diabetes may cause a sweet, fruity odour, especially if poorly controlled.

If your dog’s breath suddenly changes and they’re also drinking more, vomiting, or seem unusually tired, it’s time for a vet check. Early bloodwork can catch serious issues before they become life-threatening.

While many cases of bad breath improve with diet and brushing, some need urgent care. Call your vet if you notice:

• Bleeding from the mouth or gums
• Facial swelling or a visibly swollen jaw
• Dropping food, not eating at all, or crying when chewing
• A sudden, extremely foul “rotting” smell
• Vomiting, excessive drinking, or sudden weight loss alongside the bad breath

Prompt treatment can relieve pain quickly, and might prevent more serious complications.

1. Brush regularly. Even three times a week makes a huge difference.
2. Feed a dog dental-friendly diet and give your dog something safe to chew daily.
3. Book routine dental checks. Annual vet exams catch small issues before they become painful, expensive problems.

Is bad breath normal for dogs?

Not really. Mild odour can be normal after eating or chewing, but persistent or strong smells — especially sweet, sour, or ammonia-like — often signal dental disease or internal issues. If you notice a sudden change, it’s worth checking in with your vet.

Can I treat my dog’s bad breath at home?

You can reduce mild odour with brushing, dental chews, or special diets, but these only work if your dog’s bad breath issue is minor. If plaque or infection is already present, or if the smell is strong, home care won’t be enough. A vet check will help you treat the cause, not just mask the smell.

When should I worry about my dog’s breath?

Call your vet if bad breath comes on suddenly or is paired with other symptoms like:

• Bleeding gums or drooling
• Pawing at the mouth
• Vomiting or reduced appetite
• Swollen face or mouth
• Breath that smells metallic, sweet, or rotting

Can dental cleanings help treat bad breath?

Yes. If the smell is caused by plaque or gum disease, a professional dental clean can make a dramatic difference. Ongoing care (like brushing and dental diets) helps maintain these results.

Fresh breath is a sign of a healthy mouth and a healthier dog. Pay attention to your dog’s breath, choose the right foods and chews, and keep up with brushing to give them the best chance at strong teeth, pain-free gums, and a longer, happier life.

If in doubt, or if something doesn’t smell quite right, don’t wait. Your vet can help pinpoint the cause and get your dog’s tail (and breath!) wagging again.

This article was written by Dr Carly Brownlow