There are two main types of canine grass eating. The first is grazing where your dog eats grass and has no ill effects. Some people suggest dogs eat grass to make up for a nutritional deficiency but even dogs that eat well balanced diets will eat grass. It could also be because they enjoy the taste.
The second type of grass eating is when a dog eats grass and throws it up. This is thought to be a deliberate instinctive attempt to induce vomiting after they’ve swallowed something that makes them nauseated. Dogs that eat to make themselves vomit usually swallow grass as quickly as possible, seldom chewing it. If your dog eats grass and he or she continue retching and is unable to throw up or keeps eating grass and carries on vomiting, you should take him to see your veterinarian.