When dogs lick their loved ones it is their way of showing care and affection, as when a mother dog lovingly licks her pups or when dogs lick their masters. However, some people dislike being licked by dogs and believe incorrectly that canine saliva is unhygienic. On the contrary, since it contains antibacterial substances, the saliva of a healthy dog is harmless and actually has healing properties. In fact, the science magazine Alaska Science Forum recently published an article entitled “Dog Saliva: the Next Wonder Drug?” which discusses a 1990 experiment by University of California researchers who found that dog saliva killed the harmful bacteria E. coli and Streptococcus canes.

Moreover, a study by Nigel Benjamin of the St. Bartholomew's and Royal London School of Medicine and Dentistry revealed that human saliva contains significant levels of nitrite (NO2), which can be converted into nitric oxide, another powerful antimicrobial agent. In Benjamin’s experiment fourteen healthy subjects were instructed to lick their hands "all over" and then the amount of synthesized nitric oxide on their skin was measured. It was found that as a result of the licking, nitric oxide levels increased sharply, suggesting that "nitric oxide derived from salivary nitrite applied to the skin contributes to the antimicrobial effects of wound licking."

On a related note, the following amazing story about how a dog helped heal his owner’s severely atrophied leg appeared on icWales, a UK news website.

Mitch Bonham, owner of a Jack Russell Terrier named Milo, had surgery after a debilitating industrial accident, and although the operation was successful, while recovering he developed a condition known as Sudeck’s Atrophy whereby “his nerves became traumatized and his leg became discolored and began to wither.” Thus Mr. Bonham’s medical consultant told him that his leg might need to be amputated, but faithful Milo helped save his master's leg by continuously licking the wounded limb for hours at a time. After five weeks of this “dog’s licking therapy,” Mr. Bonham felt his leg come alive again and found that he was able to move his leg muscles. The consultant was astounded and realized that Milo had helped stimulate the nerves in his master’s leg and thus healed it.

Milo was extremely faithful and patient, giving Mr. Bonham unconditional love by instinctively licking the withering limb even though its rotten smell was almost unbearable. This beautiful example of a pure-hearted animal’s love in action is something we humans can all learn from.

References:
1. http://www.gi.alaska.edu/ScienceForum/ASF12/1234.html
2. http://www.people.virginia.edu/~rjh9u/licking.html
3. http://icwales.icnetwork.co.uk/yourwales/weirdwales/tm_objectid=15533213&method=full&siteid=50082&headline=dog-milo-cures-master-s-wound-name_page.html