http://www.healthypet.com/faq_view.aspx?id=14
Dogs and Grass Eating
Question Do dogs eat grass because they need to vomit, or do they vomit simply because they eat grass?
Answer The cause and effect relationship in animals of eating grass and then vomiting is often questioned. No one has ever proven that dogs are intelligent enough to use grass as a medicinal herb, so those in the medical profession generally believe that dogs eat grass simply because they like the taste of it and that the vomiting just follows.
Therefore, it's unlikely that a dog will eat grass or other plants in the hopes that they will settle its stomach. Be aware, however, that some plants, or grass that has been treated with fertilizer or herbicide, can cause stomach upset or other problems, some of which may be severe. See Prevent Poisonings for a list of toxic plants.
The Companion Animal Behavior Program at the University of California at Davis School of Veterinary Medicine is currently conducting a study of grass and plant eating behavior in dogs (and cats). Many theories as to why dogs eat plants have been proposed. However, this is the first scientific study to investigate this common behavior.
By taking a 20 minute, on-line survey, you can help us learn more about our canine companions!
Please go to the website to help the University of California conduct this study. It will help all dogs.
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