From Petmd.com
Dogs love to munch away on grass, and some even make it part of their daily routine. Fortunately, most experts believe it isn’t something you should worry about. So why exactly do they gobble up that green stuff in your yard?
Dogs, unlike their catty counterparts, are not carnivores. But they’re not like your garden-variety omnivores, either. For tens of thousands of years, these opportunistic scavengers have devoured anything and everything, as long as it fulfilled their basic dietary requirements.
The modern dog, partly because of evolution and domestication, is no longer like its ancestors, which frequently ate their prey entirely, including the stomach contents of plant-eating animals. Instead, dogs today seek out plants as an alternative food source. Most commonly the plant is grass — since that is what is closest at hand — but wild canines are known to eat fruits, berries, and other vegetable matter, too.
Clearly, dogs can find their nutrients in a wide range of plant foods, but that doesn’t explain why Fido usually throws up after eating grass.
