Why do Dogs Eat Grass? Because it's a source of fiber and dogs need fiber to help them with digestion. It's quite natural for dogs to eat grass. They don't always eat it, but when their stomach is "upset" (acid buildup) they might do it. Also, grass can trigger vomiting in a dog, it's like a self defense mechanism for when the dog feels he eat something bad. Is it bad for dogs to eat grass? Yes and no. No because it helps with their digestion. Yes because grass could be contaminated with herbicides and pesticides which are toxic to dogs. Nothing you can do really, if the dogs feels like eating some grass, he will. What you can do is not let him eat too much because in large quantities leaves/grass can cause a blockage. How to stop a dog from eating grass Although rare, dogs could also eat grass because they are hungry or their diet doesn't contain enough fibers (nutritional deficiency). Try switching the dogs diet to a hig...