I think most dogs eat grass when they have an upset stomach.
Some dogs eat dirt, some dogs eat carpet, and a few dogs even eat poop, and dring their Pipi.
While there is not scientifically proven reason, here are the top two theories:
As per http://www.dogs-101.biz/why-do-dogs-eat-grass Click for more information.
Dogs eat grass for the nutrients.
Instead, they use plants as an alternative food source. Grass is usually the most commonly available, but wild canines have been known to eat fruits, berries and other vegetables as well
But it’s still a mystery as to why our dogs usually throw up after eating grass.
Dogs eat grass for medicinal reasons
Sometimes it seems that a dog will seek out and use grass as a natural remedy for an upset stomach and it seems that eating grass may do the trick. When a dog eats grass, the grass blade tickles the throat and stomach lining. This sensation, may cause the dog to vomit, especially if the grass is gulped down rather than chewed.
Disclaimer:The information in this guide is general in nature and it represents research from a variety of sources. Nothing on this site is meant to substitute for professional veterinary care. The information presented on this site is not meant to replace the advice of veterinary care professionals.I recommend that if you have specific veterinary needs or concerns about your poodle or any pet, please seek the advice of a veterinarian.