We've all seen dogs sniffing each other's butts. Big dogs, little dogs, fluffy dogs, sleek dogs. They. All. Do. It. Little dogs seem especially delighted to sniff the nose-height butt of a larger dog. It's so convenient! Meanwhile, the humans who come along with the dogs for walkies are left to stand awkwardly by, laughing in embarrassment and saying things like, "Yeah, he does that."
But there's no need to be embarrassed, humans. This butt-sniffing routine is no different from you using your eyeballs to note someone's hair and clothing. Dogs can even determine the mood of another dog through butt sniffing, the same way we might notice another human's mood by seeing a smile or a frown. Let's find out how they do it.