Dogs have a secondary olfactory system that's known as the Jacobson's organ. Its nerves direct the chemical information it detects directly to the brain, so that there is no interference from other odours. It can be regarded as one canine sniffing out important information about the other dog such as its gender, emotional state, diet, and more.
Getting To Know Each Other
When one dog greets another with a nose in the derrière, it is basically getting a brief biography of its new friend, written in scent molecules and pheromones. To the sides of a dog’s butt are pouches called anal sacs; these contain glands which secrete chemicals that can tell a sniffer a lot of information about their owner, like gender, reproductive status, and clues about its health, diet, and even emotional state. Researchers studying the anal secretions of dogs and wild coyotes discovered that, next to their poppers, canines have pouches called anal sacs, which house the glands that secrete chemicals they use to get to know each other. It may seem like a strange way to go about it, but butt sniffing is just the canine version of shaking hands and introducing yourself!