Why Does My Dog’s Breath Smell Bad? A Vet Explains
Vet-written pet health advice
Bad breath in dogs is common — but persistent or particularly unpleasant breath shouldn't simply be dismissed as “dog breath”. From plaque and tartar to infected teeth, there are several reasons your dog's breath might smell bad.
The quick answer
The most common cause of bad breath in dogs is plaque and dental disease. Bacteria accumulate on the teeth and around the gumline, producing the characteristic unpleasant smell. However, sudden, particularly strong or unusual-smelling breath can sometimes indicate another dental or medical problem, so persistent bad breath is worth investigating.
Why does my dog's breath smell bad?
A dog's breath isn't expected to smell minty fresh, but persistent bad breath in dogs — also known as halitosis — isn't necessarily normal either.
The most common culprit is bacteria associated with plaque, tartar and dental disease.
Plaque is a sticky bacterial film that continually develops over the surface of the teeth. If it isn't removed, minerals in saliva can cause it to harden into tartar, also known as dental calculus.
Over time, bacteria and inflammation around the gumline can progress from gingivitis to periodontal disease, potentially affecting the tissues that support the teeth.
Common causes of bad breath in dogs
1. Plaque and tartar
This is one of the most common causes of dog bad breath. Plaque continually forms on the teeth and, without effective dental care, can mineralise into tartar — particularly around the gumline. You may notice yellow or brown deposits developing on the teeth.
2. Gingivitis and periodontal disease
Plaque accumulating around the gumline can cause inflammation and gingivitis.
More advanced periodontal disease can affect the structures supporting the teeth and may eventually result in painful, loose or infected teeth. Dogs can be surprisingly good at continuing to eat despite dental discomfort, so eating normally doesn't necessarily mean their mouth isn't painful.
3. An infected or damaged tooth
A fractured tooth, tooth-root infection or other dental problem can cause particularly unpleasant breath. You might also notice difficulty chewing, dropping food, chewing predominantly on one side or swelling around the face.
4. Something stuck in the mouth
Dogs aren't exactly renowned for making sensible decisions about what goes into their mouths. Pieces of stick, bone, grass, hair and other material can become trapped between the teeth or around the gums. This can cause irritation, infection and a distinctly unpleasant smell.
5. Something they've eaten
Sometimes the explanation really is that simple. Strong-smelling food, scavenging and the various disgusting objects dogs inexplicably consider delicacies can temporarily change the smell of their breath.
6. Other medical conditions
Less commonly, a change in your dog's breath can be associated with disease elsewhere in the body.
Kidney disease, for example, can sometimes cause an unusual ammonia-like smell, while dogs with poorly controlled diabetes may develop an unusual sweet or acetone-like smell to their breath.
Oral growths, infections and other diseases affecting the mouth can also cause halitosis. A significant or persistent change in your dog's breath therefore shouldn't automatically be assumed to be a simple dental hygiene problem.
When should I take my dog to the vet for bad breath?
If your dog's breath has become persistently unpleasant, it's worth having their mouth checked by your veterinary practice — particularly if the smell is new or getting worse.
Arrange a veterinary examination if you notice:
- Red, swollen or bleeding gums
- Heavy yellow or brown tartar build-up
- Loose, broken or discoloured teeth
- Difficulty chewing or chewing on one side
- Dropping food while eating
- Excessive drooling
- Pawing or rubbing at the mouth
- Facial swelling
- Reduced appetite or weight loss
- Blood in the saliva
- A lump or swelling inside the mouth
- A sudden or significant change in the smell of the breath
Can dental chews remove tartar from my dog's teeth?
This is an important distinction. Dental products are primarily useful for helping control new plaque accumulation — they aren't a replacement for veterinary dental treatment.
Once plaque has mineralised into firmly attached tartar, brushing, dental gels and dental treats won't simply make established dental disease disappear.
If your dog already has substantial tartar, inflamed gums, loose teeth or other signs of dental disease, arrange a veterinary dental assessment first. Home dental care becomes particularly valuable once the mouth is healthy, when the aim is to slow down plaque accumulating again.
How can I get rid of my dog's bad breath?
If dental disease has been ruled out or treated, the best way to tackle recurring dog breath is to focus on preventing plaque from accumulating again.
Different dogs tolerate different approaches, so the best dental routine is ultimately one that is safe, effective and realistic enough to maintain consistently.
Dog dental care at home
Tooth brushing remains the best option for routine plaque control, but dental gels, plaque-control products and dental treats can also form part of your dog's oral care routine.
Tooth brushing
Regular tooth brushing is the gold standard for at-home plaque control. Ideally, dogs' teeth should be brushed daily using products specifically designed for pets.
Dental gels
Some dogs would rather negotiate international peace treaties than allow you to brush their teeth. Dental gels can provide another convenient way to support routine oral hygiene, either alone or alongside brushing depending on the product.
Plaque control & dental treats
Plaque-control products and dental treats can complement brushing and help make a consistent dental routine easier to maintain.
Find the right dental routine for your pet
Browse Vetalia's range of dental care products for dogs and cats, including toothbrushes, oral gels, plaque-control products and dental treats.
Shop all dental care →How often should I clean my dog's teeth?
For the best plaque control, dogs' teeth should ideally be brushed every day.
Plaque starts accumulating again quickly after the tooth surface has been cleaned, so a consistent routine is much more useful than an enthusiastic scrub once every few weeks.
If daily brushing isn't realistic for your dog, don't abandon dental care altogether. Your veterinary team can help you decide which combination of brushing and other dental products is most appropriate for your dog.
What should healthy dog breath smell like?
There isn't really a universal definition of “normal dog breath” — and nobody is suggesting it should smell like peppermint.
However, a healthy dog's breath shouldn't be overwhelmingly foul. If you suddenly notice that your dog's breath smells much stronger than usual, particularly if the change persists, have a look at their teeth and gums and consider arranging a dental check with your vet.
Frequently asked questions about bad breath in dogs
Why does my dog's breath smell like fish?
A fishy smell may simply be related to something your dog has eaten, particularly if they eat a fish-based diet. Persistent unpleasant breath can also be caused by dental disease, so check their teeth and gums and speak to your vet if the smell continues.
Why does my dog's breath smell rotten?
Very foul or rotten-smelling breath can occur with significant periodontal disease, an infected tooth, damaged tissue or material trapped inside the mouth. A veterinary examination is advisable rather than simply trying to disguise the smell with dental products.
Why has my dog's breath suddenly started smelling bad?
A sudden change can occur because of something your dog has eaten, but it can also indicate a broken or infected tooth, foreign material trapped in the mouth or another oral problem. If you can't identify an obvious harmless cause or the smell persists, contact your vet.
Is bad breath normal in older dogs?
No — bad breath shouldn't simply be dismissed as a normal part of ageing. Dental disease becomes more common as dogs get older, which is one reason unpleasant breath may be noticed more frequently in senior dogs.
What is the best thing for bad breath in dogs?
It depends on the cause. If your dog has dental disease, the underlying problem needs to be assessed and treated. Once the mouth is healthy, regular plaque control — ideally through daily tooth brushing — can help maintain oral hygiene. Dental gels, suitable dental treats and other oral care products can also form part of a preventative routine.
Does brushing a dog's teeth help bad breath?
Yes. When bad breath is associated with plaque accumulation, regular brushing can help control the plaque and oral bacteria contributing to the smell. However, brushing won't fix an infected tooth or established periodontal disease, so persistent halitosis still warrants a veterinary check.
Vetalia Veterinary Advice: Bad breath can be an early sign of dental disease. Dental products are intended to support routine oral hygiene and aren't a substitute for veterinary diagnosis or treatment. If your dog has persistent bad breath, painful or bleeding gums, loose or damaged teeth, difficulty eating, facial swelling or other signs of illness, contact your veterinary surgeon.