Why dogs eat grass – and when to worry about it (or not)

It’s spring (yes, in Iceland it is now) and the sun is finally warming everyone´s hearts and grass pokes through the soil. When out walking your dog you will likely notice that your dog suddenly stops and begins to nibble on the fresh grass - like it’s the best thing they have eaten all week.

For some, it looks just cute, but many of you get worried, because many of you have heard that grass eating should raise alarm: Is my dog sick or feeling unwell? Is the food lacking nutrients? Are they trying to throw up? Should I stop my dog?

These thoughts are widespread. But like many beliefs that get repeated often enough, it isn’t entirely accurate. Fact: Most dogs eat grass and for the majority of them it is totally normal.

Science has not yet found one single reason why dogs eat grass. What we do know is that it’s a common behaviour, even among healthy, well-fed dogs. Surveys and studies show that a large percentage of dogs eat grass regularly. Dogs on perfectly balanced, nutrient-complete raw diets find green blades irresistible every now and then.

So why do dogs eat grass?

Some theories suggest it’s instinctual, a relict behaviour. Wild canids have been observed to ingest grass and plant material, whether directly or indirectly through their prey. So it may simply be part of their natural behaviour.

Others believe dogs may turn to grass when they are under-stimulated. The repetitive motion of chewing and the smell could simply be interesting and satisfying.

It is also possible that some dogs use grass as a form of self-medication. There are reports of dogs eating grass and then vomiting afterwards. This has led to the popular belief that dogs instinctively seek out grass to make themselves throw up when they feel unwell. But – as far as studies could find out - this seems to be the minority. Most dogs who eat grass do not vomit afterwards and they don’t seem uncomfortable before or after.

Another common belief is the suspicion that grass-eating signals a lack of nutrients or a lack of fiber. However, even dogs who eat balanced diets, including those rich in fiber, still eat grass.

So how can you tell if your dog´s grass-consumption needs attention?

The key lies in the way they do it. A dog who strolls around and casually munches a bit of grass here and there, body relaxed is likely just fine. It is similar to us collecting berries on a walk and trying them.

However, if your dog seems agitated or obsessed with eating grass, maybe pulls up tufts or eats grass much more than before, it is worth paying more attention. A marked change in behaviour or intensity can sometimes point to discomfort, nausea or an issue like reflux, gastritis or even (in rare cases) gastric torsion. If in doubt, call your vet, especially if it is paired other symptoms, e.g. vomiting, appetite changes or lethargy.

Should I stop my dog?

No, in most daily situations there is no reason. Exceptions are when grass is growing in places where it may be contaminated, e.g. on roadsides, sprayed fields or areas where chemical treatments are likely. In those cases, it is safer to gently guide your dog away.

If you feel like or suspect that your dog might be eating grass out of boredom or does it repeatedly during uneventful parts of your daily walk, it is a chance to rethink your routines. Dogs need – among physical - mental stimulation. Think about changing walking routes, scent-based activities or engaging tasks and games during your walks. If you need help or if this does not work, you can also get in touch with a dog trainer.

Summary

We do not know 100% why dogs eat grass. Unless your dog is acting differently or seems uncomfortable, it’s rarely something to be afraid of.

Sometimes grass is just grass.