In some respects, animals are to be envied. They sniff and stink happily to themselves and no one is bothered by it. On the contrary, smelling a lamppost or another animal’s rear end is like exchanging business cards. When a male dog leaves a scent mark on a tree, he leaves valuable information: “I am young, strong, and potent, so get out of my territory! Females welcome!” Even the exact time can be recognized by other dogs based on the decay of the scents. However, the next dog may try to “overspray” this message with its own messages, so it can smell quite intense at such marking spots. Only fellow dogs understand this scent language. It exists alongside the learned and instilled scent evaluation. Neither cats nor other mammals perceive the messages, let alone humans. Only other dogs are initiated into the code, and only other dogs produce dog pheromone. In them, however, it triggers reproducible, always identical “compulsive reactions”.