Testing
According to a study done at the Smithsonian, cats might be eating grass due to an instinct that can be seen in many wild carnivores as well. Several field studies have discovered that wild carnivores often eat grass and other vegetation as a means to help purge their bodies of parasites like worms. Eating vegetation is believed to stimulate the muscles in their digestive system in a way that eating meat alone just doesn’t accomplish.
This increased muscle activity helps make the animal’s digestive system less habitable for parasites and, in some cases, helps force them from the animal’s body. However, it is important to note that just because our cats are eating grass doesn’t necessarily mean they have parasites! Or that if they don’t eat grass, they don’t have parasites. The animals are simply acting on an instinct that has evolved over time.