Saliva is a liquid secreted in living organisms mouth. The physiological function of saliva is to digest foods. Inside of mouth is covered with a tissue that resist harmful digestive effects of enzymes found in saliva.
Saliva is not a dirty, infectious material itself, however spreading saliva on other tissues, over skin of human body is not healthy; because the enzymes in saliva causes digestion of healthy skin tissues, and decreases the resistance of tissues, skin resistance against some sort of bacteria.
Thus, we should teach our children that any kind of activity that leads to contamination of tissues with saliva should be avoided to keep skin healthy.
For example, that a child kisses a dog dirty with bacteria, is different or worse from
that a child touches a dog dirty with bacteria.
Since, saliva in kiss breaks dog skin cells, the harmfull bacteria of dog skin will contaminate worse kissing child.
