Just like our own ears, dog ears produce wax which needs to come out at some point. Their ears are an area on their body that they are unable to reach. Thus, they need the help of a friend to keep this area clean.
Dogs require a great deal of attention, from both their humans and their other companions. Another reason your dogs are licking each other’s ears could be one dog’s way of getting attention from the other.
If your dog suddenly becomes keen to relentlessly lick another dog’s ear, it could mean that the pup is suffering from an ear infection. Ear infections cause a discharge to occur, and it creates an odor that can attract other dogs.