Why does my dog eat grass?

Mostly because they like it. The "they're sick" theory is mostly myth — research shows fewer than 25% of dogs vomit after eating grass, and most weren't sick beforehand.

Most likely reasons: they enjoy the taste/texture, they're bored, or they're after the smells (other animals, fertiliser, decomposing leaves). Some dogs do it more in spring when grass is fresh.

When to worry: sudden frantic grass-eating combined with lip-licking, drooling, or visible discomfort can signal nausea. Recurring vomiting after grass is a vet conversation. So is eating grass to the exclusion of food, or eating it from areas you've treated with herbicides or pesticides.

Otherwise: it's a quirk, not a disease. Just keep an eye on what they're eating it from.