Why does my dog eat grass?

My dog occasionally nips off a few blades of grass when we’re out walking, and I had always heard it was a dog’s way of inducing vomiting. I accepted that widespread belief, even though I’d never seen him react by actually regurgitating. So what gives? Is he just a salad-eating dog?


It may come as a surprise to many that canines are not strictly carnivores. Those of us who have dogs may know this intuitively from the way dogs wolf down carrots or bananas or other surprising foods, including ones they shouldn’t eat. Apparently, their evolutionary history made them eat whatever was needed to get vital nutrients. Studies of wild canids of today have shown that they do indeed eat plant material; it shows up in their scat.


Unfortunately, experts don’t have a definitive answer as to why dogs munch on grass. Many people believe what I had been told: that they gobble it to induce vomiting. But perhaps it simply tastes good.


I asked Heal House Call Veterinarian Erin O’Leary about it. “There has always been a bit of a chicken or the egg about the issue,” she said. “Do they eat grass because they feel sick or do they eat grass because they like it and then throw up because they’ve eaten the grass.” She pointed me toward research by Drs. Karen Sueda, Kelly Cliff and Benjamin Hart, at the University of California, Davis, to uncover more about this perennial question.


In an article revealing the results, Dr. Hart summarized that 68% of the respondents said that their dogs ate plants on a daily or weekly basis. Only 22 % regularly vomited afterward, while 8% appeared ill beforehand. The authors of the research hypothesize that plant eating is common and, Dr. Hart writes, “It is generally unassociated with illness or a dietary deficiency but reflects an innate predisposition inherited from wild canid and felid ancestors.” He goes on to say that “plant eating likely serves a biological purpose. One explanation is that plant eating played a role in the ongoing purging of intestinal parasites … in wild canid…ancestors….”


So there you have the supposition so far. More research is needed.


So grass eating is not something to worry about, with this caveat: some lawns have been treated with toxic chemicals. If you know this to be the case, or if there isn’t a weed in sight, put a halt to the nibbling right away.


Additionally, if you notice a sudden increase in grass eating or if your dog is one who vomits after eating grass and the vomiting persists, take it as a sign that your dog may have an underlying health issue. Time to see your veterinarian for some tests to rule out gastrointestinal problems.


If you see your dog eating other plants in your house or yard, put a stop to it until you check the toxicity.


Photo credit: By Greg Bradshaw – Permission of use by oldsingerman20 has been granted by the author, FAL, https://commons.wikimedia.org/w/index.php?curid=16855844

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