I remember freshman year after breaking my leg, I had to get a surgery that left me with a pretty big scar on my knee. I never had a dog growing up, but my friend Brianna did, and every time I went over to her house her dog would lick my scar. Brianna’s mom would tell me that it was a good thing because a dog’s saliva can actually help heal wounds more quickly. Well, 3 years later I’ve decided to look a bit more into this claim.
Where Did This Start?
The belief that dog saliva can heal human wounds dates all the way back to ancient Egyptian times, when dogs were used in healing practices. “The Egyptians believed that being licked by a dog, especially on an open wound, would aid in recovery or even cure the disease causing the illness.” This concept was carried into the ancient Greek beliefs, where they would have dogs that were trained to lick wounds in many temples dedicated to Asclepius, the god of medicine and healing. According to Psychology Today, “The value of being licked by a dog is still believed by many cultures to have curative powers. There is even a contemporary French saying, “Langue de chien, langue de médecin” which translates to “A dog’s tongue is a doctor’s tongue.””
How Does It Work?
There are a couple ideas that doctors have as to why dogs saliva can possibly help heal wounds. First off, simply the physical action of the dogs tongue on a wound can be helpful by loosening any debris that may be on the surface of the wound. Although this is true, the focus of most scientific research has been on specific antibiotic compounds found in dog’s saliva. “Menno Oudhoff of the University of Amsterdam found simple proteins called histatins in saliva. These are well known for their ability to ward off infections. Some histatins also prompt cells from the skin’s surface (called the epithelium) to close over a wound more quickly.” Another set of researchers at the University of Florida at Gainesville discovered a protein called Nerve Growth Factor (NGF) in the saliva of dogs. Their study research showed that “Wounds doused with NGF healed twice as fast as untreated (that is unlicked) wounds.” In theory, the presence of these helpful proteins in dog’s saliva should be successful in healing human wounds.
Negative Effects
Yes, dog’s saliva may have some potential benefits, but this doesn’t mean that there aren’t risks involved. For example, it is known that dog’s mouths contain a bacterium called Pasteurella, which could cause a skin infection called cellulitis in humans if transmitted into a wound. “There are a number of reports of this happening, and sometimes the results have been extremely negative, causing infections that have resulted in amputations, and sometimes the resulting infections have been life threatening.” Two women, a 32 year old from Georgia and a 48 year old from Texas were both infected by their dogs, resulting in both women having their legs amputated after infection spread. One factor that needs to be noticed is the fact that these infections were caused by dog bite, not dog licking. That being said, just because dog’s have bacterium in their mouths, doesn’t necessarily mean it could infect a wound through licking. In these cases, the bacteria was deeply injected through bite, not saliva on the surface.
I wasn’t able to find any experiments on this study, but I did read through some anecdotes. However, the anecdotes were all negative, speaking about different people got infected due to dog’s licking their wounds. I think that it would be difficult to conduct an experiment to prove this concept true or not. It would require wounded people to be wiling to risk infection in order to let dogs lick their wounds. In reality, these wounds wouldn’t just heal over night. For the scientists to see if dog saliva really does have a significant effect, they would have to make sure the subject’s wound is licked everyday. Then they would have to compare it to the healing process of a wound that is healing naturally. When you think about it, if dog’s saliva was a risk free method of healing, it would already be bottled and sold to the public.
When I was young, once my grandma told me that human’s saliva have healing functions as well. I believed it. The similar claim is raised in your topic. According to a clinical pharmacologist named Dr. Nigel Benjamin, “human saliva comes in contact with skin, nitrite—a natural component of saliva—breaks down into nitric oxide, a chemical compound that is effective in protecting cuts and scratches from unwanted bacteria.” So I do believe that saliva have some healing functions.
Since I am allergic to both dog hair and dog saliva, this form of “healing” would definitely not benefit my health in anyway. However I don’t see how it could benefit anybody, like you said, saliva has bacteria that could cause further infection. If you were to do an experiment you could use 20 subjects. Each with a small wound. You could use dog saliva on 10 of them and then compare the healing results, to see if there is a correlation between saliva and how quickly the wound heals.