Scientists have a new theory about why Fido gobbles down his poop. This time it points to an evolutionary instinct possibly inherited from ancestral wolves dating back 15,000 years.

It’s not the first – and certainly won't be the last – attempt to figure out why man’s best friend eats his own feces. Theories range from existing health conditions that alter a dog’s appetite to roaming rovers looking for nutritional value in human feces. Some even suggest puppies get it from their mommas.

The newest theory, published in Veterinary Medicine and Science, says canine conspecific coprophagy – the tendency of some dogs to eat feces – is an inherited tactic to keep the den area free of parasites that could be lurking in poo.

Researchers surveyed nearly 3,000 dog owners. They didn't find a connection between diet, age, gender, or breed. They said it's not to do with potty training, either. Poop-eaters were just as easily house-trained as those who didn’t diet on stools, suggesting a normal aversion to stool in general.

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What they did find was that 16 percent of pups sampled had eaten poop at least six times, and all of them overwhelmingly preferred it fresh and less than two days old. 

It’s similar to a strategy adopted by wolves, who poop away from their dens because feces can contain parasite eggs.

But, this is life and accidents happen.

If a lame or sick wolf happens to relieve itself in the den then a wolf might ingest the stool to keep the den clean of parasites that might be transmitted in feces. Parasites’ eggs don’t hatch into infectious larvae for a few days, so if the dog eats it right away then it won’t become infected.

Does it hold that your pup’s potty mouth is really just an attempt to keep your pack safe?

Not everyone is convinced.

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The study also found that coprophagic dogs tend to be “greedy eaters”, a trait James Serpell, a professor at the University of Pennsylvania, told the Washington Post indicates a dietary motivation.

Unfortunately, researchers still aren’t able to find an effective way to deter pups from picking up after themselves. The success of products marketed to stop dogs from eating their poop, as well as behavioral training, was close to zero. It's not easy to convince your dog not to eat poop if he’s set his mind on doing so.

The study’s lead author, Dr Benjamin Hart, and his team are now working hard to create a product that will deter dogs from eating poo.

Until then, can we get some insight into why dogs roll in poop? Asking for a friend.

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