Last weekend at my parent’s house my brother’s dog, Scout, ran out the door and went straight over to a pile of horse poop and rolled in it. What gives? Why do dogs seem to get such joy from rolling in nasty, smelly stuff?
There is actually no definitive answer. There are four leading theories and all four rest on behaviors inherited from wolves. (Note that all dogs are descendants of wolves.)
1. They are covering their scent to hunt prey. They roll in smelly stuff to cover up their smell as they hunt prey. The theory is that wolves and dogs want to mask their own scent which might alert and scare their prey.
This makes sense, but there is an issue with this theory as observation of foxes and wolves has found that they tend to roll in the excrement and carcasses of other fierce predators such as mountain lions or bears. They also like other smelly substances like motor oil or perfume. If their purpose was to hide their scent, they’d want to roll in rabbit excrement or smells related to other small prey – not other predators.
2. They want to camouflage their smell from other predators. This theory is somewhat opposite from the one above. This research paper, The scent of your enemy is my friend? The acquisition of large carnivore scent by a smaller carnivore, from the Journal of Ethology, argues that canines prefer scents of larger animals in order hide themselves, smell-wise, from larger predators. The research was performed over a few years on grey foxes and found the foxes liked to rub themselves in mountain lion urine. In an interview with the BBC the lead researcher of the paper said: “Coyotes are so much bigger than grey foxes, but seem to want to eliminate them as there is competition for resources between them. The foxes cannot really fight back, so they are exploiting the puma scent to get some form of protection. Smelling like a puma might give them time to escape.”
3. They are trying to leave their own scent behind. Just as your dog likes to “mark” his territory by peeing on all sorts of things, dogs also like to try to cover other smells with their own by rolling around. For example, dogs will often roll all over a new dog bed, supposedly to leave their scent, and some animal behavior experts think that dogs rub up against people to deposit their scent on them and mark them as members of their pack.
This theory makes sense but there doesn’t seem to be any research studies supporting it.
4. They are communicating with their “Pack.” Researchers studying wolves and hyenas have noted that in addition to eating wild prey these canines also roll in the carcasses as well. Pat Goodman of Wolf Park: “When presented with a side of elk, they both rolled and ate,” she says. “I speculated that food scent on the wolf’s breath and on its fur indicated that there were more leftovers to scavenge, for wolves that wanted to backtrack to the source of the odor.” Wolves who smell a pack-mate who has rolled in something have been observed tracking the odor back to it’s origin.
An issue with this theory is the dogs seem to be willing to roll in most anything that smells bad – not just potential food for their pack.
So, which theory is correct? More research and study is needed to find out. Maybe it’s just fun to roll in stinky stuff. I’m going to try it out this weekend. I may report back.
Other IFODs about dogs:
Can dogs recognize other dogs by sight alone? Big Dog, Little Dog
Are dog years really equal to 7 human years? Dog Years
Some benefits of dog ownership: Happiness is a Warm Dog
Do Dogs Really Like to be Petted?
A few surprising facts about dog food
Is there a section on how to stop your dog from rolling in poo?
“Truth is not truth” and this is a great example of this fashionable oxymoron(?). Great evidence of the persistence of evolutionary behaviors—the reason you cannot “test” this today is that the evolutionary predicate for this behavior no longer exists….not unlike our fear of snakes—think how long that has persisted….