Why Do Dogs Eat Grass?

Dogs eat many strange things. My dog’s favorite snack is old tissues from the bathroom garbage. It’s gross! Though dog owners may roll their eyes and get annoyed at their dogs for digging through the trash, one thing that sparks concern is when dogs eat grass. You might wonder, is this behavior safe? Is it okay? Is it normal?

So…Why DO Dogs Eat Grass?

The truth is, no one is really sure what drives a dog to snack on grass! But there are many theories, which will be discussed in this article.

Theory 1: Your dog eats grass because it is missing a vitamin or nutrient in its diet.

Writing for Purdue University’s College of Veterinary Medicine, Andrea Retiger takes issue with this theory. She states most dog foods are plant-based and therefore, your dog should be getting the proper amount of vitamins or minerals in its diet without needing grass as a supplement.

Theory 2: It’s evolution

Some believe that wild dogs ate both meat and plants and therefore domesticated dogs now eat meat and plants. A second evolutionary theory claims that dogs developed an instinctual liking of grass because they digested it while digesting the stomachs of their prey.

Theory 3: They are trying to relieve an upset stomach

This seems to be a chicken or egg theory. How do they know eating grass will help alleviate abdominal discomfort as opposed to a roll of toilet paper? Are dogs really eating grass to make themselves throw up to relieve an upset stomach? You might wonder if they are throwing up because they ate too much grass instead of the other way around.

Why Do Dogs Eat Grass?

Theory 4: Dogs eat grass because they like it

Maybe it is as simple as that after all. The smell, taste, and texture of grass are appealing to dogs and so they eat it. Andrea Retiger poses that, “Maybe dogs just like to eat grass. Maybe it tastes good or has a pleasing texture. Perhaps it’s a compulsive behavior or something we condition with unintentional reinforcement. Who can say for sure why dogs choose to eat what they do? What makes a rotting carcass and the new sofa such delectable treats?”


There is not much research on why dogs eat grass. A 2008 study titled, Characterization of Plant Eating in Dogs, from the University of California, Davis, by Sueda, Hart, et al. surveyed dog owners on the internet to test these theories. 68% of the 1571 people surveyed stated their dogs eat plants daily or weekly. The remainder of the participants stated their dog eats plants once a month or less. 79% of participants reported grass was their dog’s vegetation of choice. 9% of the participants (141 people surveyed) reported that their dog appeared ill before eating grass. 22% of the participants (345 people surveyed) reported their dog vomited frequently after eating grass. The study also found no correlation between dogs eating grass and particular breeds, sexes, whether or not they’re fixed, etc. The study did find that young dogs ate more plants on average, ate more plants that weren’t grass, mostly did not appear sick before eating, and did not vomit after eating plants. The researchers concluded that eating grass and other plants is a normal domestic canine behavior.

Though domestic dogs do not generally have the same intestinal parasitic issues as wild animals, the evolution theory is supported by wolf scat research. Observational research reports discuss worms and grass that were found in wolf droppings. These findings suggest the grass was used to help rid the wolves of intestinal worms. Scouring, as it is called, is found in many species of animals including bears and chimpanzees. Domestic dogs might be carrying on a survival instinct from their ancestors.

Is It Safe for My Dog to Eat Grass?

The answer to whether it is safe for dogs to eat grass is a bit nuanced. If dogs are eating grass simply because they like the texture, yes it is safe. What isn’t safe is if the dog is eating grass sprayed with pesticides or herbicides, which can be toxic if eaten. If your dog is eating both grass and plants, be sure those plants are not toxic. Many houseplants are toxic and pet owners are not aware of their risks.

When Should I Call the Vet?

If your dog eats grass more frequently than usual or your dog suddenly starts eating grass and never has before, it might be time to bring it to the vet for a checkup. If your dog becomes lethargic or unwell after eating grass, you should go to the vet immediately. When it comes to your pet’s safety, always err on the side of caution.

What Should I Do About the Behavior?

Why Do Dogs Eat Grass?

If you and your dog have a mutual agreement that snacking on grass okay and there aren’t any signs of feeling ill, then you don’t need to take any action to stop it unless you want to. Positive reinforcement training can help redirect your dog’s behavior. When you notice your dog start to eat grass, walk your pup away from the area, or use a stop command. Immediately give him a treat for complying. Be patient. Your dog will eventually catch on and you can reduce or eliminate the behavior. If you suspect your dog is eating grass out of boredom, try increasing exercise routines and mental activities. If you want to make sure your pup is eating grass in a safe and healthy way, consider creating a dedicated dog-friendly grass and herb garden. You will know what is being ingested into your dog’s body and you will be able to control the amount eaten.

The Takeaway

At the end of the day, dogs will be dogs and oftentimes dogs eat grass. You love your dog and you want what’s best for your pet. As long as there is no indication of any distress or illness when eating grass you can let your dog be. Always make sure your dog is acting in a safe manner and always contact your vet if you have any concerns.