Why does my dog always sniff cats', dogs', and other animals' bottoms? - Ask Scarlett

Ranger Rick, Sept, 1996 by K.T. Scanlin

Why does my dog always sniff cats', dogs', and other animals' bottoms? K.T. Scanlin; Boise, ID

I guess that behavior is kind of embarrassing to you, huh? But for a dog, it's perfectly natural. Smell is the best sense your dog has. And dogs get lots of information from sniffing.

Your dog sniffs the bottoms of other animals because that's how dogs greet each other. It's their way of "getting acquainted." There are glands in the tail area that give off all kinds of different odors. Each odor tells your dog something different about the other animal (such as whether it's male or female, weak or strong, young or old, healthy or sick). It's a very interesting way to carry on a conversation, don't you think?