This has been a subject of debate for some time: Do dogs eat grass to vomit, or do they vomit as a result of eating ate grass? It seems to be there are dogs that eat grass just because they crave greens, and others purposely eat it to vomit. In my experience, I have seen dogs eat grass because they like it, and some to make themselves sick.When they do it when they're nauseous they often eat it quickly and indiscriminately, taking mouthfuls at once rather than calmly. One curious thing I am seeing in my dogs is the choice of grass. Often, the tender grass is just for pleasure, while the rougher, dryer grass is for the purpose of vomiting as the roughage seems to better work to stimulate the vomiting reflex.