DOGS’ KISSES, LICKS AND SALIVA THAT HEALS
By Dr. Michael W. Fox
There are many misconceptions about why dogs “kiss”, lick so much and the health-risks of their saliva. Many people erroneously believe dogs to be “unclean.” Many enjoy their dog’s kisses and some dogs greet and lick faces and hands excessively because they are “perpetual puppies”—hyper social, or insecure.
Over-sanitation (and associated “germaphobia”) creates problems just like a lack of sanitation. Exposure to the bacteria that dogs bring into our homes on their paws and pass on when they lick family members have been shown to enrich the microbiomes of children which in turn give greater protection against infections and allergies. Pollen in their fur may also be a source of desensitizing exposure. But all who have compromised immune systems should limit their exposure to dog-licking and cat-scratching.
I have received more than one letter from elderly people whose dogs have licked and healed sores on their legs and arms, reminiscent of the Biblical story of Leprosy-afflicted Lazarus being cared for by street dogs. Dog saliva contains the antibacterial enzyme lysozyme, and stimulating the skin around the wounds through licking would increase healing blood flow. Lysozyme is an important component of antibacterial in saliva. It participates in the host nonimmune defense along with salivary secretory immunoglobulin (SIgA) against bacteria, maintaining the steady state equilibrium of the oral cavity environment.
There is evidence that human saliva has similar healing and also analgesic properties. Saliva from humans has yielded a natural painkiller dubbed opiorphin that is up to six times more powerful than morphine, researchers claim. This is probably present in the saliva of dogs and other mammals. Also, human saliva contains exosomes which play a role in immune system function and may well be present in other mammals. The finding of RNA-containing exosomes in saliva (and breast milk), suggests that the shuttling of RNA via exosomes may occur between individuals, during kissing or breastfeeding. The therapeutic value of exosomes is currently under investigation.
Concerning potential infections from in-home animals, always wash hands before preparing food and before eating; wash out pets’ food and water bowls daily because they could contain Salmonella, E. coli and other bacteria from pet foods that could infect family members; be meticulous with hand-washing and no-hand-to-mouth contact after handling animals like lizards and terrapins that I advise people not to keep because some people have been hospitalized after contracting Salmonella infections from such creatures who should be left in the wild.