A natural instinct

We’ve all seen how livestock, including cows, sheep and goats, love gnawing on grass. It’s fine for grazing to be their pastime because their stomachs are able to digest all of the cellulose in grass. Unlike those animals, dogs are omnivores, related to meat-eating hunters like wolves. Yet if you own a dog, you may have seen him snacking on grass while out in your backyard or on a walk. So, why do dogs eat grass? Is your dog not getting enough food? Could he be sick? Or is it another puzzle springing from weird-yet-normal dog behaviour, like “Why do dogs chase their tails?” It turns out that different dogs eat grass for different reasons. Let’s take a look at the most likely ones.
It’s in their DNA

Though we think of canines as historically carnivorous, they actually evolved as omnivores that would eat whatever was available, including vegetation. Also, the prey animals that our dogs’ ancestors would eat were usually herbivores, so those wild dogs were indirectly consuming plant life. Instinct is a pretty logical answer to “Why do dogs eat grass?”
A much less understandable habit, on the other hand, is why dogs like to lick their paws.
A form of pica is behind it

The urge to eat substances other than food is a condition called pica. While pica is a cause for concern in people, it’s usually nothing more than a sign of boredom in dogs. To make your dog’s day less ho-hum, add a few minutes to your regular walks, take him into your backyard or to a dog park for a fetch session, and treat him to a few new chew toys or puzzle toys for those times when you can’t be with him.
Help your dog avoid depression by recognising these 9 behavioural changes.