Why Dogs Sniff Each Other's Rear Ends

dog sniffing butt of other dog
Gerard Brown/Dorling Kindersley/Getty Images

Mutual butt-sniffing is one of the first things that happens when two dogs meet. This may seem disgusting or embarrassing to you, but your dog sees it differently. Why do dogs sniff each other's rear ends? Is this a healthy and normal thing to do? 

Your Dog's Sense of Smell

A dog's olfactory system is complex and advanced, making its sense of smell far superior to that of a human. To give you an idea of the difference, consider the fact that humans have about 5 million olfactory receptors in their noses and dogs have about 220 million.

 Dogs can smell layers upon layers of scents even when we can smell nothing. That's an impressive nose.

If you had a nose like that, you'd probably want to sniff everything too! Dogs sniff their way through life for two main reasons:

  1. Enjoyment: Stuff smells good! Smelling things is fun. Smelling feels good and stimulating.
  2. Information: Dogs want to figure out or learn more about something or someone.

Why Dogs Sniff Butts

Many people think of butt-sniffing among dogs as a type of greeting, but it's so much more than that. Through sniffing, dogs are able to learn things about each other. Every animal has his or her own unique scent. This includes humans, dogs, cats, and all other animals. While you or I can only vaguely detect a personal scent, our dogs pick up a number of clues through their noses. These scents are especially potent around the genitals and anus (the location of the anal sacs, which collect odorous fluid).

Scents in this area can tell another dog about gender, reproductive status, diet, health status, temperament, and much more. A dog can also remember scents and therefore determine whether or not he has met this particular dog before.

So, when a dog meets another dog, they each have stories to tell. People make small talk at dinner parties.

Dogs sniff one another's butts. It's normal behavior.

Many dogs also try to find out more about humans through, ahem, crotch-sniffing. This is often much to our embarrassment. Don't worry, it's not a problem with you. It's just canine nature. However, dog owners should discourage this behavior. If your dog is crotch-sniffing someone, please redirect him somewhere else! Otherwise, you may find that people really dislike your dog.

Should I Let My Dog Sniff Other Dogs?

If both dogs are healthy, well-socialized, and supervised, it's actually a good idea to let them "sniff it out" as much as they want (provided each dog is tolerating it well). Dogs may actually be less likely to fight if they take an adequate amount of "getting-to-sniff-you" time with one another. However, some dogs may get intense with the sniffing while other dogs need their personal space.

Watch the behavior and body language of all dogs. If one dog is overdoing it and the other dog seems annoyed or stresses, then the owners should call their dogs away. Also, it's ideal to let dogs meet and play in pairs. Dogs are more likely to get overexcited in groups, which can lead to fights