Why Dogs Eat Grass — The Explanation Vets Actually Give

Nearly every dog does it. Most owners have a theory about why. And for decades, the prevailing explanation — that dogs eat grass to make themselves vomit when they feel ill — has been repeated so often that it became accepted as fact.

Research has since complicated that story significantly.

What the Research Actually Shows

A study published in the journal Applied Animal Behaviour Science surveyed over 1,500 dog owners about their dogs' grass-eating behavior. The findings were revealing: fewer than 25% of grass-eating dogs vomited afterward, and fewer than 10% showed signs of illness before eating grass.

This doesn't support the "sick dog self-medicating" theory as a primary explanation. It suggests most grass-eating is not medically motivated.

The More Likely Explanations

It tastes good. This is genuinely the simplest and most supported explanation. Dogs are omnivores with a long evolutionary history that includes plant consumption. Fresh grass, particularly in spring, may simply be palatable.

Fiber seeking. Some researchers believe dogs eat grass when their diet is low in fiber, as a way to add roughage. Dogs fed higher-fiber diets do appear to eat less grass on average.

Ancestral behavior. Wild canids regularly consume plant material — both directly and through the stomach contents of prey. Grass eating may be a remnant of this behavior that has no specific purpose in domestic dogs but hasn't been selected against.

Boredom or oral stimulation. For some dogs, particularly those with limited enrichment, grass eating may simply be something to do with their mouth.

When to Be Concerned

Occasional grass eating is not a health concern. Become concerned if: your dog is eating grass obsessively and frantically (this can indicate nausea), if vomiting consistently follows, or if the grass may have been treated with pesticides or herbicides.

Otherwise: your dog probably just likes grass. And that's fine.