Dogs can be weird and gross. Some dogs' favorite way to achieve optimal grotesquerie is to roll in poop, to the great dismay of the humans around them. Why do they do this?
Dogs have a penchant for rolling in smelly things. The bad news: we're still not exactly sure why. The good news: we have a few theories.
Why dogs roll around in poop.
Scent Masking For Predators: Dogs might roll around in the poop of others because it masks their scent. In the wild, this would be beneficial to dogs because it would throw predators off their trail.
Scent Masking For Prey: In the wild, dogs need to consider their predators, but they also need to consider their prey. Another theory, similar to the one above, is that rolling in poop throws prey off their trail, so that the prey wouldn't easily sense the dogs coming.
Depositing their own scent: Stephen Harris of the University of Bristol in the UK posits that dogs are trying to deposit their scent, not mask it. Depositing their scent would send a message to other dogs that this is their territory, and they're ready to defend it if necessary.
Establishing a group odor: A study observed Ethiopian wolves rolling on the ground following a meal, which may serve the social function of establishing a group odor. Though that idea may sound strange and somewhat gross to us, a group odor would aid bonding and togetherness among group members, potentially increasing chances of survival.
In the past, researchers have floated the theory that rolling in poop acts as some sort of insect repellant, but that theory has since been debunked.
How to stop a dog from rolling in poop.
Needless to say, having a dog who rolls in poop can be unsettling and wildly inconvenient.
If your dog is a roller, the best course of action is to know the signs, and to try to redirect them when they seem like they're about to roll. Most dogs will zero in on their scent of choice before rolling in it, so watch for that behavior. You might also observe your dog doing a "pre-roll pose," where they kind of smash their face into the ground before lowering the rest of their body down (in a sort of horrifying slow-motion sequence).
Once you spot these signs, redirect your dog using the "leave it" command (or whatever command you use to tell your dog to leave something alone). If your dog doesn't know the "leave it" command, now is a good time to teach it. Use positive reinforcement training to teach your dog how to leave an object alone. This command comes in handy in many different circumstances.
If your dog rolls in poop, they're not trying to annoy you, they're just acting on an age-old instinct (of some variety). Teaching them to "leave it" should make your life a little easier — and a little less stinky.