80% of dogs eat grass. Learn 7 vet-backed reasons and when to worry.
Disclaimer: This content is for informational purposes only. Always consult your veterinarian. Furli is not a veterinary service.
If you have ever watched your dog mow through a patch of grass like a tiny lawn mower, you are far from alone. Studies published in the Journal of Veterinary Behavior and Applied Animal Behaviour Science consistently report that grass-eating is the single most commonly observed plant-eating behavior in domestic dogs, with prevalence rates between 68% and 79% of dogs surveyed. Most of these dogs showed zero signs of illness before, during, or after grazing.
Still, the behavior raises questions. Why would a carnivore-leaning omnivore choose to eat something with virtually no caloric value? Veterinary researchers have spent decades trying to pin down an answer, and what they have found is more nuanced than the old "dogs eat grass to make themselves throw up" myth.
A landmark 2008 study at the University of California, Davis surveyed 1,571 dog owners. The findings challenged several popular assumptions:
A follow-up study in 2009, using direct observation rather than owner surveys, confirmed these numbers. The researchers concluded that grass-eating in dogs is a normal behavior with no single definitive cause, rather than a symptom of disease.
Wild canids—wolves, coyotes, foxes—regularly consume plant material. Analysis of wild wolf scat consistently finds grass and other plant fibers. The most widely accepted explanation is that domestic dogs have inherited a hardwired tendency to eat plant material as part of a broadly omnivorous survival strategy. Your dog is not making a conscious dietary choice; the behavior is closer to a reflex passed down through tens of thousands of years of evolution.
Grass is composed largely of insoluble fiber. Some veterinary nutritionists propose that dogs may seek out grass when their diet lacks sufficient roughage. Fiber plays a critical role in gut motility—it keeps things moving through the intestinal tract at the right speed. Dogs fed high-quality diets with adequate fiber content may eat grass less frequently, though this has not been conclusively proven in controlled trials.
If your dog seems to target specific long-bladed grasses and chews them deliberately (rather than grabbing mouthfuls randomly), a fiber deficiency is worth discussing with your vet. Switching to a food with higher fiber content or adding a tablespoon of plain canned pumpkin to meals may reduce the behavior.
The "upset stomach" theory is the one most owners have heard. While research shows it applies to a minority of cases, it is not entirely wrong. Some dogs do seem to eat grass frantically—with a sense of urgency, gulping without chewing, often choosing coarser grass blades—and then vomit shortly after. The rough texture of unchewed grass can tickle the throat and stomach lining, triggering the vomit reflex.
This pattern looks distinctly different from casual grazing. A dog that is self-medicating will often:
If you see this pattern once or twice a month, it is typically nothing to worry about. If it happens multiple times a week, underlying GI issues—acid reflux, inflammatory bowel disease, food sensitivities—should be investigated.
Dogs that spend long stretches in the yard with nothing to do are more likely to eat grass, dirt, sticks, and anything else available. This is not nutritional seeking—it is behavioral. The chewing motion itself is soothing (similar to why anxious dogs chew furniture), and grass is the most accessible thing in most yards.
Increasing physical exercise, providing puzzle feeders, and rotating toys can reduce boredom-related grass eating significantly. If the behavior only occurs when the dog is left alone in the yard but never during walks or play sessions, boredom is likely the primary driver.
Sometimes the simplest answer is the right one: some dogs genuinely like eating grass. Young, tender shoots in spring are moist and slightly sweet. Dogs that selectively nibble on new growth while ignoring dry or mature grass are probably just enjoying a snack. This is the canine equivalent of eating a salad—not because they have to, but because it tastes good.
In rare cases, excessive grass eating falls under pica—the consumption of non-food items. True pica is distinguished from casual grazing by its compulsive nature: the dog eats grass constantly, cannot be redirected, and may also eat dirt, rocks, paper, or fabric. Pica can stem from nutritional deficiencies (especially iron or zinc), neurological conditions, or severe anxiety. This warrants a full veterinary workup including bloodwork.
Most grass-eating is harmless. Schedule a vet visit if you observe any of the following:
While any dog can eat grass, some breeds seem more prone to the behavior. Labrador Retrievers and Beagles—breeds with strong oral fixations and food motivation—are frequently reported grass-eaters. Herding breeds like Border Collies and Australian Shepherds sometimes graze during downtime in the yard, likely driven by boredom and high energy levels. Miniature Schnauzers and other breeds prone to pancreatitis and GI sensitivity may eat grass more often as a stomach-soothing reflex.
Grass-eating is one of those dog behaviors that worries owners far more than it should. For the vast majority of dogs, it is a normal, harmless, inherited behavior. Keep your lawn safe, keep an eye on frequency and associated symptoms, and save the worry for situations that truly warrant it. If you want to track your dog's habits over time—including eating patterns, stomach issues, and behavioral changes—Furli makes it easy to log everything and share the data with your veterinarian at the next checkup.
