Your dog eats grass and then vomits a short time after. You think there is something wrong. Maybe your dog has an upset tummy. Maybe it has a dietary deficiency. Or maybe you think they crave the same vegetation their wild ancestors got when they ate the intestines of their prey first. Let’s look at what we know from scientific studies.

 Possible reasons why dogs eat grass:

• They have a dietary deficiency
• Grass relieves stomach upset
• They are like their wolf ancestors
• None of the above

Dietary deficiency 

Studies have shown over and over again that dogs will eat grass even though their diets are complete in vitamins, minerals, and fiber. Even dogs eating adequate or excessive calories will also eat grass. 

Grass relieves stomach upset 

The popular belief is that dogs eat grass to relieve stomach upset. There is nothing to support this idea. Any dog that eats grass will throw up grass, healthy or sick. So eating and throwing up grass tells us nothing about how the dog’s stomach is feeling. That would be like us not feeling just right and eating something to make ourselves throw up and then saying our stomach is the problem because we threw up. 

They are like their wolf ancestors 

Others believe that because wolves eat the stomach and intestines of their prey first that today’s dogs need plants in their diet because they don’t eat prey. Again, there is no scientific evidence to support this because dogs don’t digest vegetables and fruits as well as we do. The good stuff in plants passes right through them without benefit. Wolves benefit from broken-down proteins, fats, and sugars in their prey’s intestines, not the vegetable matter. 

Quiz answer – (D) None of the above.

It appears that eating grass is like eating sticks, paper, rocks, and other non-food objects (pica). It is a vice that makes no nutritional sense. Maybe one day the mystery will be solved. Until then, don't assume that your dog is nutritionally deprived or sick because it eats grass. She eats grass because she wants to not because she has to.