|Dogs commonly eat grass, and there are several explanations that have been offered for this behavior. One, wild canids (e.g., wolves and fox) eat all of an animal when they catch it. Since they eat many herbivores (plant-eating animals), they end up eating a lot of grasses and plants that were in the intestines of these animals. In addition, they have been known to eat certain berries and other plant material. Dogs then, may eat grass because, in reality, it is a normal part of their diet.
Many times, dogs will vomit after eating grass. Did they eat grass to make them vomit? Or did they vomit because they ate grass? It is a mystery, but it seems that some dogs may eat vegetation when they have an upset stomach.
The third reason - they just like it. Some dogs have certain species of grass or plant material that they will search out and eat. We know a beagle who can pick raspberries faster than his owner.
In any case, grass eating is basically a normal behavior, and is not of concern unless your dog does it excessively.