Grass eating commonly confuses dog owners, according to dog trainer Cesar Milan. Some experts think the behavior is a normal search for nutrients outside the dog's regular diet, while others believe it's due to boredom or to help heal an upset stomach.
While some experts believe dogs eat grass to treat upset stomachs, some evidence indicates that most dogs that eat grass don't feel sick, explains WebMD. Eating grass may help dogs improve digestion due to the extra fiber intake, but humans still don't fully understand this canine behavior. Another possible explanation may be that the dog is bored or stressed. Chewing is a natural way for dogs to relax and pass time.