Many of our dogs’ comical or unusual behaviors stem from instinct.

Dog's wolf ancestors lived in the wild and fended for themselves, so every action had a specific purpose. Although today’s pet dogs are domesticated, they are still animals, and many of their wild urges and behaviors come to the surface during playing or feeding. 

Here are some common questions about dog behavior and possible explanations for dogs' actions:

1. Why do dogs eat grass?

Certainly, he is not a cow, so why is he chewing on the lawn? A popular explanation is that dogs eat grass when they have an upset tummy because it helps them to vomit, purging them of whatever is making them sick. If you are worried about your dog’s grass intake, try adding some veggies—such as unsalted green beans or a cut-up carrot—to his diet.

Another common belief is that dogs eat grass to improve digestion or to address a dietary deficiency, such as a need for fiber. Some believe that dogs instinctually seek the minerals in the grass or the actual plant fibers themselves. When the wild relatives of dogs (including wolves and coyotes) consume their prey, they also eat the animal’s stomach and its contents, which often includes grass. This may create a craving for them to consume grass. There is no one answer, but there are plenty of theories.

To test the popular theory that dogs eat grass because they know they are sick and need to vomit, veterinarians at the University of California, Davis, School of Veterinary Medicine conducted a survey in which they questioned 1,600 pet owners. Here are their results:

• 80 percent of healthy dogs with access to plants had eaten grass or other plants
• 68 percent of responders said their dogs ate plants daily or weekly
• Only 8 percent of dogs exhibited signs of illness prior to ingesting plants
• Only 22 percent of dogs vomited after eating plants

The researchers concluded that eating grass may not be directly related to feelings of illness. They believe that the consumption of grass is likely an inherited trait from their ancestors who also ate grass. It is believed that wolves eat grass to help purge internal parasites and to prevent the parasites from accumulating in the digestive system.

Try to keep your dog from eating grass by not leaving him unattended in grassy areas or by telling him “leave it” whenever he starts to go for a mouthful of greenery. If your dog absolutely insists on eating grass, limit it to your own yard and do not use fertilizer or weed killer on your grass, as these chemicals can make dogs sick. This educational website describes these reasons in detail and gives good insight into some of the theories behind dogs' grass eating.

2. Why do dogs roll in poop and dead animals?

There are a few possible reasons for this, all of which have instinctual roots. Many centuries ago, when dogs ran wild, they rolled in foul-smelling materials to mask their own distinct scent. According to the ASPCA, by camouflaging their scent, they were able to blend in with their environment, enabling them to sneak up,  unnoticed, on prey. 

The ASPCA also gives another possibility, which is that rolling in a mess is a dog’s way of leaving his mark (the same idea as peeing on a tree). By rolling in that spot, he is leaving behind remnants of his own scent and marking it as his territory. Rubbing his body on the spot tells all other dogs that this smelly, rotten pile is his and only HIS, so stay away! 

Some dogs are more likely to roll in a “mess” after they have a bath so they can smell more like themselves. Having a fresh, flowery scent may smell good to us, but it is not natural for dogs. They would much rather smell like a dog, so try using an unscented shampoo when bathing your dog. You know how much you hate it when those ladies at the mall spray you unwillingly with perfume that smells like a toilet? That is how our dogs feel when we use fragrant shampoo on them, and they will roll in anything to get that good old dog scent back on their fur. The stinkier the better!

A third popular theory is that dogs instinctively roll in the stuff to communicate to other dogs what they have found. When they travel back to their pack, remnants of their amazing discovery will be all over them, alerting their friends that something interesting is nearby. Believe it or not, dead animal or poop makes a very pleasant eau de parfum for our canine friends.

3. Why do dogs turn around in circles before laying down?

My dog, Kaya, does five circles before curling up into a furry ball and settling down in her cozy bed. Always five—never more, never less!

I always laugh at her little bedtime routine because I assume she is trying to make her bed as comfortable as possible. Almost all domestic and wild dogs perform this ritual at some point. This behavior likely stems from their wild ancestors’  tendency to dig their own shelter or place to rest—think of it as their “nesting routine.”

Human nesting routines consist of fluffing pillows and flattening sheets before bed time. In the wild, dogs turned in circles to flatten out grass and vegetation, and to shoo away any rodents or insects, making a cozy place for them to lay down. In hot weather, they would dig up an area of soil to protect themselves from the heat of the sun.

According to the ASPCA, by digging a hole in the ground, dogs can curl themselves up to utilize the cool temperature of the soil and protect themselves from the heat. So, although many of our dogs today have their own comfy beds to sleep in, the circling habit is still prevalent. Many dogs will even dig at the blankets and pillows they lie on and move them around to create the perfect sleeping area. Some dogs even burrow under the sheets!

The next time you see your dog circling around, think about how hard his ancestors had to work just for a comfortable place to rest. In some ways, it is how he “makes his bed.”  Don’t say your dog never does any chores!

4.  Why do dogs shake their toys?

This is a predatory instinct that originates from their predecessors’ hunting behaviors.

We must remember that our domestic dogs came from their wolf ancestors, and wolves hunt to eat. As unpleasant as it sounds, shaking the prey back and forth is an effective way for a wolf to kill its prey. By clamping down and giving the animal a few vigorous shakes, the wolf can easily and quickly break the animal's neck or spine. In those days, a dog who didn’t play with his food didn’t eat!

According to the Woof Report, our dogs today still have many of these instincts deep inside them, and they often come out during play or feeding time. When a dog shakes a toy, he is making sure it is good and dead.

Other hunting behaviors that can come out during play are stalking, pouncing and chasing. Shaking toys during play is completely normal and is a dog’s outlet for his predatory instincts. 

5. Why do dogs bury bones?

Call it primitive hoarding if you will. After devouring their prey, dogs' wild ancestors would bury any leftover food to return to it when food got scarce—waste not, want not!

In those days, they only ate what they killed, so they had to make the most of every meal. But the competition was fierce, and there were plenty of other predators who would leap at the chance to chow down on some other dog's hard-earned kill! These clever animals concealed their leftovers in the ground so that they could come back to it when the need arose—this was before Tupperware! (Inside of a Dog)

These days, many dogs are lucky enough to be well-fed—with only the finest organic treats from Petsmart or Whole Foods—and would never go hungry. But, that doesn’t mean our pups don’t have the urge to hoard food, treats or bones. Their instincts tell them that what they can’t eat they should bury and save for later, because—hey, who doesn’t love leftovers! 

There are so many theories about why dogs do the things they do, and many of the most logical explanations all lead to instincts. If you ever see your dog doing something unusual and you want to figure out the reason for the behavior, try to imagine what purpose this behavior might have served a dog's ancestors living in the wild.

You might come up with your own explanation for your dog's behaviors and tendencies!