There are many bacteria in dog saliva. They will keep licking their asses, licking their wounds and licking their dogs, and some of the worst infections will happen. The eggs of Echinococcus granulosus and other major germs will enter the dog's mouth, and then it will lick its owner. This parasite may enter the owner's liver, brain or intestine, forming a golf ball-sized hydatid cyst. Once ruptured, this potentially fatal cyst will release thousands of new eggs.