Dog Bad Breath: Why It Happens and What Helps

What it usually means

Plaque is a sticky film of bacteria that builds up on the teeth every day. Within days it starts to harden into tartar, the yellow-brown crust you may see near the gum line, especially on the back teeth. The bacteria produce smelly sulfur compounds, and as they spread under the gums they cause gingivitis, then periodontal disease, which damages the tissues that hold the teeth in place.

Other mouth causes include food or a stick wedged between teeth, a broken or infected tooth, a mouth ulcer, and, less often, an oral tumor. Small and toy breeds, whose teeth are crowded into small jaws, and flat-faced breeds tend to develop dental disease earlier and more severely.

Causes beyond the mouth

Sometimes the smell is not dental at all. Dogs who eat poop, garbage, or dead things on walks will have bad breath for a while afterward. Some dogs also smell from an infected skin fold around the lips, which is common in breeds with heavy jowls such as Spaniels and Bulldogs.

Less commonly, bad breath can be a sign of illness elsewhere, such as kidney disease, which can give the breath an ammonia-like odor, or uncontrolled diabetes. These are more likely in an older dog whose breath has changed, or in a dog who is also drinking more, losing weight, or off their food, and they are found with blood and urine tests.

When to call your vet today

Book a dental check soon if your dog has bad breath that does not go away, visible tartar, red or bleeding gums, or loose or discolored teeth. Dental disease often hurts long before dogs show it, so do not wait for them to stop eating.

Call the same day if your dog is drooling a lot, pawing at the mouth, chewing on one side, dropping food, or has a swelling on the face or under the eye, which can be a tooth root abscess. Also call promptly if bad breath comes with increased thirst, weight loss, vomiting, or tiredness.

When it's an emergency

Bad breath alone is not an emergency. Seek urgent care if your dog cannot close their mouth, has a large swelling of the face or jaw, is bleeding heavily from the mouth, or something is stuck across the roof of the mouth or between the teeth and they are distressed.

Also go promptly if bad breath comes with vomiting, weakness, not eating, and much more thirst or urination than usual, since that combination can mean kidney trouble or another serious illness. If your dog may have chewed an electrical cord, battery, or caustic product, call your vet right away.

What you can safely do at home

Brushing is the single most effective thing you can do. Use a soft brush or finger brush and a toothpaste made for dogs, never human toothpaste, which can contain xylitol or other ingredients that are unsafe for dogs. Start slowly with a few teeth at a time and lots of praise, and work up to brushing daily.

Dental chews, water additives, and dental diets can help as an extra. Look for products carrying the Veterinary Oral Health Council seal, which shows they have evidence behind them. Avoid very hard chews such as antlers, bones, and hooves, which can break teeth. No product removes tartar that is already there.

What the vet will likely check

Your vet will examine the teeth, gums, and mouth, and may grade the dental disease. A proper cleaning is done under general anesthesia, because it involves scaling under the gum line, where the disease actually is, and dental X-rays to look at the roots. Loose or badly diseased teeth may need to be removed.

Cleaning without anesthesia only removes visible tartar from the crowns and leaves the disease underneath, so most vets advise against it. If the mouth looks healthy, your vet may suggest blood and urine tests to look for other causes of the smell.

Preventing bad breath in dogs

Start brushing when your dog is young so it becomes routine, and keep up a daily habit if you can; several times a week is still worthwhile. Have your vet check your dog's teeth at least once a year, and more often for small breeds and dogs with a history of dental problems.

Professional cleanings at the intervals your vet suggests keep periodontal disease from getting a foothold. Stop poop eating and garbage raiding where you can, and keep the lip folds of jowly breeds clean and dry.

This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.