Why do dogs eat grass?

Most dogs eat grass simply because they like it. It’s a widespread behavior — studies estimate 60-80% of dogs eat plants regularly, and grass is the most common choice. Veterinary behaviorists note that wild canids eat plant matter too, so it may be an inherited habit from before domestication.

The old idea that dogs eat grass only when they feel sick and need to vomit is mostly wrong. Research shows that fewer than 25% of dogs vomit after eating grass, and the majority eat it with no ill effects at all. Dogs who eat grass and then vomit likely had an upset stomach beforehand — the grass was eaten because of the nausea, not the cause of it.

Other likely reasons include a dietary fiber gap — grass provides roughage that commercial dog food doesn’t always supply enough of — or simple boredom, especially in dogs left alone in the yard for long stretches. As long as the grass hasn’t been treated with pesticides or herbicides, occasional grass-eating is harmless. Consult a vet if it becomes compulsive, is accompanied by vomiting or diarrhea, or if your dog stops eating their regular food.