Why Does My Dog Have Bad Breath?

Plaque and tartar

Dental disease is the most common cause of bad breath in dogs. It starts with plaque, a sticky, colourless build-up on the teeth made from bacteria, food and saliva.

Plaque can harden into tartar, which is a hard white-to-brown coating. VCA says this can happen within days. The smell itself comes mainly from bacteria that produce smelly sulphur compounds.

Gum disease

Plaque and tartar inflame the gums, which is called gingivitis. An early sign is a thin red line along the gum edge. As it progresses, MSD says the gums change from coral-pink to red or purple, the edge swells and the gums bleed easily. Smelly breath is common at this stage.

Gingivitis can be reversed with proper cleaning. Periodontitis, however, damages the ligaments and bone that support the teeth, and that loss is permanent. MSD says it usually begins at around 4 to 6 years old.

Age and breed

Vets Now says most dogs over three have some dental disease. Small and flat-faced breeds are more prone to oral disease because their teeth sit closer together. MSD also says small breeds get periodontitis more often than large breeds.

Something stuck in the mouth, or a lump

A bone or stick stuck in the mouth can cause a bad smell, especially if it causes a wound or infection. Lumps in the mouth often become infected and smell. MSD says bad breath is one of the common signs of malignant (cancerous) mouth tumours. Only a vet can tell what a lump is.

Infection and inflammation in the mouth

PDSA lists infections and tooth root abscesses as causes. Inflammation of the mouth, tongue or throat commonly causes it too, often along with drooling.

Inflamed or infected lip folds can smell very bad and may give a foul-smelling discharge. MSD says lip fold problems occur in breeds with drooping lips, such as spaniels, English Bulldogs and Saint Bernards. Uncommon conditions, such as trenchmouth (severe gum inflammation) and fungal overgrowth, can also cause it.

Kidney disease

PDSA says kidney disease can give breath that smells of ammonia, which it compares to bleach. The reason is that toxins and waste products build up in the body. MSD also says chronic kidney failure can cause inflammation and sores in the mouth.

Diabetes

PDSA says diabetes can give sweet-smelling breath, similar to pear drops or nail polish remover.

Diet

Food can change how a dog's breath smells. PDSA gives fish-based diets as an example, because they can make the breath smell fishy. A change of diet may alter the smell too.

A smell is only a clue, so ask your vet to find the actual cause.

Daily brushing

After a professional clean, VCA says daily plaque control is essential to stop the problem coming back. Daily brushing is the best prevention. MSD puts it this way: gum disease will not develop around clean teeth.

Use dog toothpaste only. Dogs Trust warns that human toothpaste can be toxic for dogs. It also says enzymatic dog toothpaste helps break down plaque and reduces the smell.

Introduce brushing gradually, with rewards, and ideally from puppyhood. If your dog pulls away or seems uncomfortable, stop and take a break. If your dog will not allow brushing, MSD says wiping the outside of the teeth with gauze at least every 2 to 3 days can help.

If you suspect gum disease, or your dog has never had its teeth brushed, speak to your vet first. Vets Now says brushing may be painful or ineffective in that case.

Chews, diets and products

Dogs Trust says brushing is the best way to keep your dog's mouth healthy, and that water additives, certain foods, treats or toys can be used alongside it. Always check with your vet before using any of them.

VCA and MSD both point to the Veterinary Oral Health Council (VOHC). VCA says the VOHC only accepts dental products proven to reduce plaque and tartar, including dental diets, treats and water additives.

Be careful with hard objects, because they can fracture teeth. MSD lists real bones, hooves, antlers and hard nylon toys as examples to avoid. Vets Now advises avoiding bones and sticks. Because advice on chews varies, ask your vet which are suitable for your dog.

Regular dental checks

VCA and the Royal Kennel Club both recommend dental exams at least twice a year. This matters because Vets Now says bacteria from periodontal disease can enter the bloodstream, and affected pets are more likely to develop heart, kidney and liver disease.