Why dogs and cats eat grass

Have you seen your dog eating grass or your cat nibbling vegetation and wondered why? 

First, eating grass is very common in dogs and cats. In a 2008 survey, almost 80% of pet parents reported seeing their dog eat grass. Science reported that a 2019 survey of cat parents found that 71% of cats ate grass at least six times. Researchers reported that the wild relatives of dogs and cats (canids and felids) eat vegetation based on analysis of their feces. 

The most common reason many of us think that our pets eat grass is to help them throw up. For instance, my dog Toby often nibbles on particular slender grasses that appear to be tasty, but occassionally he rushes outside and gobbles up any vegetation he can find (and then vomits). These behaviors are similar to other dogs.

In the surveys mentioned above, 22% of dogs and 25% of cats vomited after eating grass. If the pet acts ill before eating grass, it is more likely to vomit afterward. However, most pets do not act ill before eating grass - leading the scientists to conclude that vomiting is usually an after-effect of eating grass. This behavior may make evolutionary sense to help get rid of internal parasites. Some animals, like chimpanzees, use plants to "self-medicate", including eating prickly plants that may help remove parasites.

So, if your furry friend likes to nibble grass it is probably nothing to worry about. If you notice excessive vomiting, you should contact your veterinarian. And be sure to keep pets away from poisonous plants (see lists for dogs and cats). Consider providing grass plants for pets that are kept indoors to allow them to express this natural behavior.