Many things are typically listed on veterinary websites as causes of bad breath. Among them, kidney disease, mouth tumors, dental disease and a few others. It seems never to be entertained by vets that bad breath might be a normal part of canine life.
While bad breath may very well be one of the indications of underlying issues, especially since almost all commercially fed dogs have them, I’ve hardly known a single dog in my life that hasn’t had bad breath, including lots of healthy ones.
One theory about cause
My last very long-lived dog who died at 19, with all his teeth, had awful breath. He was not crate trained, so I always cut his food up for him so he wouldn’t haul it around the house. When a dog has to use his back cutting teeth to cut and tear apart his food, the flossing action of the food helps keep the teeth relatively clean. When a dog eats meat but does not cut his own bites, particles of the food lodge in the teeth and putrefy. This is what produces the repulsive smell, but it is not a sign of anything bad on its own.
That’s the theory, but it conflicts a bit with reality as I will explain a bit farther along.
Is bad breath really a danger sign?
It’s quite a different matter when a dog has bad breath AND other symptoms. My dog whose breath could clear a room was completely asymptomatic and healthy in every way – great energy, enthusiasm for life (see him fetching here at age 17), no itching, scooting, coughing, or other outward signs of ill health. Considering this and the many other healthy dogs I’ve known who had bad breath, I’d have to conclude that bad breath means nothing UNLESS it is accompanied by more meaningful signs, such as symptoms that are known to indicate disease. In which case, it’s those OTHER symptoms that should motivate you to action. And by that I don’t necessarily mean veterinary intervention, because most of the conditions that are thought to cause bad breath are reversible with dietary improvement, and vets cannot help with that. They don’t even acknowledge that it’s possible to reverse disease, generally. And even if they did acknowledge it, they’d oppose it!
Do wild dogs have bad breath?
After all this, I strongly suspect that bad breath is a natural part of life for dogs and has been since their arrival on this planet. There’s no information I’m aware of that tells us what wolf breath smells like, because there are so few cases of humans getting close enough to truly wild wolves to smell their breath. But history is stiff with accounts of humans getting attacked by other omnivores, bears notably, and their abominable breath is one thing that is almost always noted and reported. If bad breath is common and normal in bears, is it not reasonable to think it’s probably a normal part of life for dogs too?
Does it help to brush teeth?
I’m unqualified to say whether tooth brushing, so encouraged by the vet industry, has any effect on bad breath at all. That’s because, for one thing, I’ve never brushed a dog’s teeth in my life. For another, no objective evidence exists that brushing improves breath. IF brushing does mitigate bad breath and if the dog is otherwise in danger of being tossed into the street by his people, I suppose the benefit of brushing is worth the time and discomfort to the dog. But to me tooth brushing is rather like bathing, ear cleaning and sundry other external cleanliness rituals that have very little positive effect on a dog’s health. So little, in fact, that dogs whose owners perform them still end up with the issues that they are supposed to prevent, which makes veterinary cash registers sing, which is the whole point of the veterinary industry, after all.
So, I think once again what we have here is the veterinary industry not missing an opportunity to frighten people into their offices. People will say that there’s nothing to be lost by taking a dog with bad breath to the vet “just to be sure”. I would differ, however, based on what I know about how vets use office calls to further frighten dog owners into buying useless and harmful products, including disease-causing “vet approved” commercial dog food, and even scare them away from proper home feeding, as they typically do.