Why do dogs eat grass?

You are halfway through a walk, and your dog stops, lowers their head and begins to graze like a small, determined sheep. Is something wrong? Are they sick? Missing something in their diet?

Almost certainly not.

What the research says

When researchers at the University of California, Davis surveyed more than 1,500 dog owners, grass eating turned out to be extremely common — most dogs did it regularly. Only a small minority seemed unwell beforehand, and most dogs did not vomit afterwards. In other words, the popular idea that dogs eat grass to make themselves sick does not fit most of what dogs actually do.

Wolves and wild dogs eat plant material too, including grass. It may help move things through the gut, or it may simply be something dogs have always done.

The ordinary reasons

• They like it. Fresh spring grass seems to be the most popular.
• Boredom. Young dogs with little to do will chew anything, including lawns.
• Habit. Once it starts, it becomes part of the walk.

When it is worth a closer look

Talk to your vet if your dog eats grass frantically, suddenly starts doing it much more, vomits often, has diarrhoea, weight loss, or eats other strange things like soil or stones. Those can point to a digestive problem or, in the case of non-food items, a condition called pica.

Grass seeds are the real danger

In summer, the arrow-shaped seeds of some wild grasses work their way into ears, noses, eyes and between toes. A sudden fit of sneezing, head shaking or licking at a paw after a walk through long grass is a classic sign, and it needs a vet.

So let them graze — on clean grass, away from chemicals. It is one of those things dogs do simply because they are dogs.