Myth: Dogs Have Cleaner Mouths Than Humans

Oct. 14, 2005 — -- Pet lovers can't get enough affection from their pooches. And if licking is loving, they get a lot of loving.

But is it really safe to kiss a dog, considering where they often put their mouths?

"Their saliva is much cleaner and if you have a cut or anything, if they lick it -- it's healing," one woman told "20/20" while being interviewed in New York City.

Proof From a Veterinarian

To find out just who has a cleaner mouth, we asked veterinarian and fellow dog lover Marty Becker, author of "Chicken Soup for the Dog Owner's Soul," to offer his opinion.

"They raid the garbage can. You know, we give each other a peck on the cheek when we say hello, they give each other a peck on the rear end," said Becker. "All you got to do is look, watch, smell and you'll realize that that is not true."

He thinks the myth that a dog's mouth is clean stems from their practice of licking their wounds.

"And they'll be licking that wound and you'll notice that the wound heals very fast … what that tongue does is it gets rid of the dead tissue," said Becker.

He compares that tongue lashing to the work of a surgeon who cleans out a wound, and said the licking also stimulates circulation.

Go Ahead, Give Them a Kiss

If you want to give your pooch a kiss, it may be safer than kissing another human.

Becker says many of the bacteria in the mouth of a dog are species specific, so it won't harm its owner.

"So a staph or a strep for a human is not transmissible to a dog, if you were to kiss it, and vice versa," said Becker.

Bottom line -- you're more likely to get a serious illness from kissing a person than kissing a dog. But since dogs do transmit some germs, Becker has some advice: "Keep the vaccines current. Good external parasite control, good internal parasite control. You're going to be good to go."

And then, he says you can kiss them all you want.

"They love us unconditionally, they make us laugh," said Becker. "If we're going to give them a little kiss to thank them for that, then that's good by me."