Susanna Pilny for redOrbit.com – Your Universe Online
Dog owners should be familiar with this: You get a small cut while chopping vegetables and suddenly your dog is on you like a shark to blood (or like Kanye to himself). Some people let their dogs lick their wounds because it’s said to promote healing and because “their mouths are cleaner than ours,” but if everything the general populace knew as a fact were true, half of us would be dead from daddy longlegs bites and swimming after eating.
So how true is it?
As it turns out, it’s kind of true. First off, the physical act of licking itself helps to clean debris from the injury: the saliva loosens it, and the tongue removes it.
Beyond that, the saliva itself actually contains proteins that help promote healing. One of them is known as histatin, which helps you heal by preventing infections and by promoting the skin to close over the injured area. Other proteins are antibacterial, like lysozyme and thiocyanate. A third recognized protein is called Nerve Growth Factor (NGF), which literally does what its name entails: It grows and maintains nerve cells, and upon exposure it wounds it halves the length of time for wound healing.
The final known component of dog saliva that helps heal wounds is also what helps men of a certain age who have had trouble…rising to certain occasions. Nitrate is concentrated in saliva, which is converted into nitric oxide inside the wound. It’s not entirely clear how nitric oxide promotes healing, but it does increase blood flow locally, meaning the body is able to transport more of its own healing factors to the area faster—which is also how Viagra works, minus the healing factors.
This all sounds really great, but there’s one small snag:
Dog saliva contains potentially harmful bacteria like Pasteurella, thereby giving you an infection in your papercut. And if your dog gets too close to his feces (or another dog’s behind), he or she can have E. coli in there too. These overly-friendly dogs can also get parasites in their mouths through the same mechanism; Giardia is a possibility.
So letting your dog lick your cuts might not be such a great idea—even just regular dog kisses have been linked to gum disease in humans. And besides, humans themselves have healing factors in their own saliva and brush their teeth regularly, so licking your own wounds is probably a safer bet.