Many people have heard the persistent rumor that, bad breath aside, dogs have cleaner mouths than humans. Do they, or is this statement just a rationalization we make after dogs lick their hindquarters and then out faces?
Simply put, dogs do not have cleaner mouth. One proof is that dogs, just like your average human, tend to have halitosis.
Bad breath comes in large part from the digestion of oral microbes. As they feast upon food matter, dead cells and tooth enamel, these bacteria release sulfuric molecules that give breath its unpleasant odor. Dogs are as prone to this situations as people. In fact, as they age, many dogs develop chronic halitosis, a condition that is essentially there to stay.
Veterinarian Marty Becker, author of Chicken Soup for the Dog Owner's Soul, told ABC News that one look at a dog's dietary habits is enough to put the notion of canine oral cleanliness to rest - and put you off your lunch, to boot.
Becker said that many dogs will, if allowed, lick their rear ends, lap at wounds and consume garbage, toilet water or cat feces. These practices are not exactly what one would expect of a clean mouth.
He added that the myth could stem from the fact that many bacteria in dog's mouths only have health effects among canines. This may be why getting a good-morning lick from a household pet rarely seems to result in illness.
Of course, the canine mouth could contain fewer bacteria that happen to be more virulent. By definition, that would make a dog's mouth cleaner than a human's, even though the risk of microbial transmission would be the same overall.
However, this does not appear to be the case. The Straight Dope reports that, in independent tests, canine and human saliva grow the same average number of bacterial colonies when placed in Petri dishes.
The news sources adds that the amount of bacteria doesn't so much vary by species as by individual. So, could your dog's mouth be cleaner than yours? It very well could, depending on whose oral hygiene is better.
Just as some dogs have very fresh breath, occasionally a human can suffer from halitosis that would make the hardiest canine shudder.
While dogs can require time-intensive oral care to keep their exhalations smelling clean, neutralizing human bad breath is relatively simple. People with oral odor may consider flossing and brushing thoroughly, after which they can gargle a specialty breath freshener to kill what odor remains.