The Nose KNOWS!

Dogs can have some pretty strange behaviors but one really takes the cake. Why do dogs feel compelled to sniff human rears and crotches? It’s so embarrassing! You’ve probably had it happen to you; maybe it was your dog acting up when a friend comes over, immediately zeroing in on their private region for a quick sniff. Perhaps you’re out and see a friend with a dog when the dog comes over to you and smells your crotch. You try to hide your embarrassment but seriously, it’s so annoying!

Dogs don’t know that this greeting is unwelcome to humans. In fact, dogs commonly smell the rear of another dog upon meeting as a sort of handshake. Butt sniffing is a very natural, instinctive, and basic form of dog-to-dog communication that helps share information, kind of like a status update. When dogs meet, this quick sniff is how they say “hi” or get reacquainted after time apart.

Dogs have a very keen sense of smell, which some experts estimate is anywhere from 40 times to 100,000 times more sensitive than the human sense of smell. People have approximately 5 million odor receptors in their dose, but dogs have a whopping estimated 220 million.

Another major part of canine communication is the presence of apocrine scent glands on each side of dogs’ rectums. These organs, called anal glands, produce strong-smelling secretions that communicate the sex of the dog, what the dog is eating, and even some clues about a dog’s emotional state or readiness for mating. Although it is difficult for humans to completely understand this kind of communication (since we don’t share it), the “sniff” is thought to also tell dogs if the encounter is likely to be friendly or not friendly.

Some dogs interact with humans as they would another dog, greeting them with a crotch or butt sniff. Humans also have many different scent glands in their genital area, so it’s not a surprise that a dog’s highly tuned nose would find the smell intriguing.