Using logic akin to "Chocolate cake? It has flour, eggs and milk. It’s virtually health food. You should eat it every day.", AllPetNews.com has an article on its site entitled "Dog saliva has healing properties." The article focuses on potential beneficial compounds in saliva, with specific reference to a University of Florida (Gainesville) discovery of nerve growth factor (NGF) in saliva (although I can’t find any reference to nerve growth factor in dog saliva on PubMed).
The article states "Wounds that were treated with NGF actually healed twice as fast as untreated wounds, indicating that if a dog does lick a humans wound, it could in fact lead to a faster recovery."
The problem here is taking some controlled research data and spinning it out of control. Putting synthesized or concentrated nerve growth factor on a wound in a controlled manner is different from putting saliva on a wound, which is also different from having a dog lick it. You have to consider the whole picture when evaluating potential treatments. For example, rubbing alcohol kills bacteria nicely but that doesn’t mean it’s a good idea to put it on a wound to prevent infection. It hurts and it damages tissue. While it may kill superficial bacteria, the tissue damage can ultimately increase the risk of infection.
While there are certainly some compounds in dog (and human) saliva that stimulate healing, those potential benefits need to be weighed against the potential adverse effects, particularly infection. The oral cavity of the dog contains billions of bacteria from hundreds of different bacterial species. Many of these are able to cause infection given the right circumstances. A wound helps create the right circumstance by breaking down the body’s normal protective barriers.
The article does mention some dangers, although only with licking of deep wounds (a wound doesn’t have to be deep to become infected), and concludes with:
"Although the healing properties outweigh the negative impacts there will always be a number of people that find it in their best interest to treat a wound by cleaning it with soap and water…."
- At this point, there’s no evidence that the beneficial properties of dog saliva outweigh the negative impacts. In reality, people would be better off if they carefully cleaned wounds with soap and water. Licking may not cause a problem in many (or even most) situations, but it can lead to serious infection, and the lack of clear evidence of benefit alongside documented risks indicate that this is an inappropriate activity.