Why Do Dogs Sniff Each Other’s Rear Ends?

Strange as it may seem, the truth is when two dogs cross paths on the street, they usually stop and sniff each other's rear ends. To be more precise, dogs sniff each other's anus, which is where the anal glands are located — the glands that release the scent that identifies and characterizes each dog.

Dogs recognize each other by scent, and the same goes when they don't know each other — they introduce themselves by sniffing each other's rear end. As unpleasant as it might seem to us on a personal, human level, for dogs it's the most natural thing in the world. So we should always let our dog sniff other dogs' rear ends, and let other dogs sniff its own.

Why Do Dogs Sniff Each Other's Rear Ends?

Dogs have a very personal scent around their anus, due to a fluid released by their anal glands. This scent is unique, the same way fingerprints are unique to humans. So each dog has a completely different scent from every other dog — a fully personal scent.

Thanks to this scent, dogs can learn a lot about the dog they're sniffing. They can tell its approximate age, its diet, its mood, and even its health status, among many other things.

Letting them sniff and be sniffed is a fundamental part of properly socializing a dog — it's an essential, fundamental form of communication between dogs (remember, their sense of smell is thousands and thousands of times more developed than a human's).

We should never stop our dog from sniffing another dog's tail area, nor stop another dog from sniffing our dog's rear end. It's a completely natural, necessary act between dogs.

Why Do Dogs Sniff Their Genitals?

Besides sniffing the anus, which is completely common and normal, dogs also tend to sniff their private parts, their genitals. A dog's genitals also carry scent information, so other dogs can gather even more information just by sniffing a bit.

A dog's urine leaves a very distinctive scent that other dogs easily identify — it's not as personal a scent as the anal glands', but it's still fairly personal.

This way, if our dog sniffs other dogs' genitals, it can tell whether it's peed somewhere our dog has walked, whether it's female or male, whether a female is in heat, whether it's sick, and so on.

This is completely normal and natural — sometimes they'll even lick it a little, to intensify the scent further and, in a way, taste it. This is how dogs communicate, and we shouldn't bother them while they're doing it — it's their way of communicating.