Why Are Dogs Fascinated with Grass?

Why Are Dogs Fascinated with Grass?

Southern California is in the midst of a severe drought and most of us, myself included, have let our lawns die.

In fact, my dogs don't even like dead grass; I dug up the grass and added in wood chips to cover the dirt. So when we had a nice soaking rain a week ago and tiny green shoots started poking up in the local park, my dogs went nuts. All three of them began munching on the new green grass like cows, and they rolled and rolled and rolled. Thankfully, my dogs weren't the only ones acting like this; just about every dog walking in the park that morning was doing the same thing. So what's the attraction? What is it about grass that so many dogs enjoy? I decided to do some research and the first thing I found is there really isn't much information available. Apparently it's an accepted fact that dogs love grass and that's it. There are lots of guesses, some anecdotal information and a few old wives' tales. Nothing in the way of science, though. Although that's slightly disappointing, it just triggered my curiosity even more.

Old Wives' Tales Have a Grain of Truth, but Only a Grain

The most commonly shared reason why dogs eat grass is that the dog has an upset stomach and eating grass will make him vomit. Some dogs do vomit after eating grass. Several veterinarians I talked to felt that the scratchiness of the grass as it was being swallowed was more likely to trigger vomiting than the grass in the dog's stomach. The rough edges of the grass could do the same thing as the finger down the throat that a person might do. Another old wives' tale is that the dog will eat grass to vomit because he has worms. None of the veterinarians I talked to had any comment on this. Although scientific research is lacking on this subject, some anecdotal research has been done, primarily queries of dog owners. Most dog owners say their dog has shown no sign of illness of any kind prior to the grass consumption; no worms, no tummy ache and no other known illness. Plus, in this poll, fewer than 10 percent of the dogs vomited after eating grass. Why this became such a prevalent and oft-repeated myth I don't know. Perhaps it began a long time ago when dogs' health was poorer than it is today and most dogs did have parasites and an upset stomach. We do know, though, that grass consumption is seen in almost all canines, wild and domesticated, at some time. Wolves, coyotes and many other wild canines will eat fresh growing grass (as my dogs did) and, although a few vomit afterwards, the vast majority of them do not.
©istockphoto/EJMPhotos ©istockphoto/EJMPhotos

Does Grass Satisfy a Nutritional Deficiency?

Green plants have a cellulose covering around their cell walls. Because dogs can't digest cellulose, unless those walls are broached in some manner, the plants will be defecated in much the same form as they were swallowed. You've probably already seen this. Corn kernels and chewed pieces of carrots are easily seen in the dog's feces and are readily recognizable. If your dog has eaten quite a bit of grass, you've seen the grass in your dog's feces looking just like it did when swallowed. With plants you want your dog to derive some nourishment from, the cellulose must be broached to make the nutrition in the food available. Steaming or cooking the plants (usually greens and other vegetables), chopping, crushing or pureeing the food breaks down the cellulose. Therefore, when your dog eats raw, growing grass, it isn't serving to satisfy a nutritional deficiency. However, dogs often eat non-food items (called pica) to satisfy a craving, and dogs who lack something in their diet often do have cravings. Their body might be saying, "Eat something! Anything!" Grass might be the easiest thing to find and eat.

Grass can Satisfy a Need for Fiber

Although scientifically dogs are classified as carnivores, a strict meat diet won't provide enough fiber for healthy digestion. Plus, some dogs do need more fiber than others. Although grass in its natural form isn't digestible by the dog, it can keep things moving through the digestive tract. If your dog is having issues with defection, that could cause him to graze more. However, grass can also be irritating to the bowels. Wide bladed grasses with rough edges can actually scratch or even cut sensitive tissues as it moves through your dog. So even though grass can satisfy your dog's fiber needs, there are better ways to do it.
©istockphoto/novvy ©istockphoto/novvy

Grass is Great for Rolling

Your dogs, like mine, have munched on that sweet green grass and then, when they've had enough, they throw themselves to the ground and roll. My usually dignified 11-year-old Australian Shepherd, Bashir, was on his back, wiggling back and forth, as if scratching his back on the grass. Why? We don't know. The best guess is that it feels good. It probably also smells good. The grass blades crush under the dog's movements and release scents pleasing to the dog, and since a dog's sense of smell is his most important sense, it's easy to see why he likes it. If I pick a twig of peppermint or catnip from my garden and drop it on the ground or the floor inside the house, my dogs will roll on top of that, too.

A Word of Caution

Although for the most part it's relatively safe to let your dog eat and roll in grass, there are some dangers to keep in mind. Limit the amount eaten if your dog has a tendency to be compulsive about it. Too much grass can cause problems in the stomach and in the digestive tract. Plus, grass is often treated with weed killers, insecticides, and fertilizers, many of which are dangerous for your dog to consume or roll in. If you're going to let him enjoy grass, do so in your yard or a local area where you know how the grass has been treated.
Back to Blog