Let a dog loose and he will happily go digging into the dirtiest bins and stinkiest vats. Why do they do it? Well, garbage smells delicious and tastes good to dogs.

Dogs have an amazing sense of smell. They have 300 million receptors for smell in their noses, while humans have only six million. People can make use of this sniffing ability to train dogs to detect illegal drugs, explosives and endangered species, and to help locate people lost in the woods.

While you might not like how your trash smells, to your dog it is an appealing buffet brimming with apple cores, banana peels, meat scraps, and stale bread. Even used napkins and paper towels are tempting to dogs when they are smeared with and carry the smell of yesterday’s lunch.

If dogs can find trace amounts of explosives or a person buried under six feet of snow after an avalanche, they are certainly capable of locating last night’s pizza crust and chicken bones in the kitchen garbage can.

Even empty cans smell inviting to dogs. Trash cans in kitchens and bathrooms are often at their nose level, too, making for easy access. Add to that the fact that if the dog got into the garbage once and found something tasty, they will likely keep searching with the hope of being rewarded again.

Thrill of the hunt

Searching and digging around for food is natural for dogs because it provides some of the thrill of the hunt, even if they just ate and aren’t hungry.

The most successful prehistoric dogs ate the bones and scraps that humans left behind more than 10,000 years ago. Hanging around humans and their garbage was a way they could get plenty to eat. Even your pup today has some of those same old searching instincts.

While our trash has changed from the days of hunting and gathering, the discarded paper napkins, plastic wrappers, and food scraps we throw away all still smell like food to dogs. And this scavenging behaviour is still hardwired in our pampered pets. Although it may look to us like they’re playing, our dogs’ sniffing out and tearing things up from the trash and tossing them around mimics what their ancestors did when they tugged on and tore up an animal carcass they had found.

One can take advantage of this instinct and use “snuffle mats” — cloth or paper where food is hidden — or puzzle feeding toys to keep their pups’ minds active. Having to hunt for and find their food helps them use their noses and sharpens their skills.

Dangerous habit

A vet inspects cuts in a dog’s mouth, acquired while rummaging garbage

While spreading trash all over the home may be natural for dogs, cleaning it up is no fun for the people they live with. And if your dog pokes his nose in a garbage can, he could be in danger. Eating plastic bags, string, chicken bones, chemicals or rotten food can cause blockages, diarrhoea and poisoning. Commonly referred to as “garbage gut,” garbage poisoning can be life-threatening. Dogs are known to have cut their tongues and mouths on cans or broken glass.

Hide or guide to abide

It can be hard to train a dog to leave garbage alone, especially if they have found a tasty morsel or two by raiding the trash can in the past. Invest in a garbage can with a lid closed by a latch that they can’t open. If that fails, keep garbage — especially food scraps — out of reach behind closed doors.

No one knows exactly what goes through dogs’ minds. And yet, looking at what motivates your canine companion and how dog behaviours have evolved may help explain why these animals do the things they do.

When Shrestha Bhattacharya got her first dog he was so naughty she named him Pondo, after the Bengali idiom for complete disarray, “londo bhondo”. “But I knew dogs have a tendency to go sniffing into the kitchen and dustbin, so I trained him from the start against it,” says Shrestha of AE Block.

This she did by keeping the dustbin in the kitchen, and keeping Pondo at the door of the kitchen. “Every time he tried to enter, I uttered a stern ‘no, ‘ and whenever he took a step back, I rewarded him with treats,” she says. This training in his puppy days was fool-proof and we’ve never had trouble with him going through the trash, or even into the kitchen, now.”