We've all heard the saying "Dogs have cleaner mouths than people." But do they? Today we shine some light on this often quoted but hugely misunderstood statement.

Do dogs actually have cleaner mouths than people? by Laura French

The short answer: No. Both humans and dogs have plenty of oral bacteria. Dogs may have more, given their tendency to snack on road kill and raid the cat litter box. An article in the Journal of the American Veterinary Medical Association (JAVMA) reports that “More than 64 species of bacteria may be found in the mouths of dogs,” including staph, strep, and e-coli.

An old axiom was that a bite from a human was more likely to get infected than a bite from a dog. In 1995, the Journal of the American Academy of Dermatology debunked that idea. In general, bites on the hand, whatever the source, are more likely to get infected because the teeth force the germs from the surface of the hand into the blood stream, according to JAVMA.

A 2005 story on ABC’s 20/20 news program theorized people noticed dogs licking their wounds to heal them and deduced that the dogs’ saliva had some germ-fighting ability. Dr. Marty Becker, author of "Chicken Soup for the Dog Lover’s Soul," told 20/20 that it isn’t an antibacterial property in the saliva that supports healing. Rather, the dog’s tongue removes infected tissue and stimulates circulation.

On the other hand, you may be better off kissing the dog. Staph, strep and rhinoviruses don’t generally carry back and forth between species. If the dog is vaccinated against rabies and kept free of parasites, that wet slurp on your cheek probably won’t do you any harm, Dr. Becker concluded.