Is there any truth to this widely-held belief?
Imagine for a moment that you’re sitting in a park on a pleasant summer day. A group of children are playing nearby, a dog is romping with them, and several parents are chatting as they watch over the children. A little boy in shorts trips, falls, and skins his knee. He goes running to his mother for comfort, with the dog alongside him. The boy’s mother looks at his knee, hugs him, and tells him he’ll be okay. The dog sniffs the boy’s knee and then starts licking it.
The assorted parents fall into one of two camps. One group of parents protests the dog licking the wound and expresses concern about germs and possible infection. The other bunch of parents tells the dog to keep licking and tries to tell the first set of parents that a dog’s saliva will actually help the wound heal.
What evidence exists to prove it?
This idea has been with mankind for a very long time. Historical documents indicate both the ancient Egyptians and the ancient Greeks believed in the healing power of a dog’s lick. But is there any truth to this?
At the very least, the dog’s licking cleanses the area. The more a dog licks, the more dirt and loose skin will adhere to the saliva on its tongue and be removed from the open sore. There’s even some anecdotal evidence that a dog licking the wound makes it feel better.
Sores in the mouth seem to heal quickly and with less scarring than they do elsewhere on the body. Since one of the differences in the mouth is the presence of saliva, scientists have studied it to see if there is a correlation.
Nitrites, which are found in saliva, break down into nitric acid when exposed to skin. Nitric acid helps protect against bacterial infections. Additionally, histatins, a type of simple protein known to ward off infection, are found in saliva. Some histatins also help the re-growth of skin over a wound, speeding recovery. By the way, these substances are found in human saliva as well as the saliva in a dog.
So with substances known to be present in saliva that can both ward off infection and encourage recovery, it’s a good idea to let your dog lick your wounds, right? Not necessarily.
For all the good things that reside in your dog’s saliva, there can be bad components as well. Pasteurella is bacteria that is common in the mouths of mammals. Although this bacteria causes no problems in the mouth, if it is introduced into a deep wound it can cause an infection that can result in amputation or even become life-threatening.
In addition, dogs lick themselves (including their rear ends) and sometime eat things that can introduce other unwanted bacteria in their mouths. Dogs’ digestive systems are different than humans’ and bacteria that doesn’t bother dogs can present serious issues in humans.
There may be some advantages to having your dog lick your wounds, but there are potential hazards there as well. You probably don’t need to drag your dog off if he starts licking your sore, but you might not want to encourage it, either.