Why Do Dogs Eat Grass?

You’ve heard the common misunderstandings about dogs, like the long-held notion that dogs only see in black and white, when in fact, science tells us they do see color, just not in the same way as humans.

But misunderstanding a dog’s health can be dangerous.

So, what does science say about dogs grazing on the green? The University of California Davis, one of the nation’s leading veterinary institutions, recently conducted a study to weed out the popular misunderstandings for dogs eating grass.

Do dogs eat grass to induce vomiting or appease an upset stomach?

Perhaps.

But the UC Davis results suggest this may not be the primary reason. For the study, twenty-five UC Davis students monitored their dogs’ diets, habits, and bodily reactions over a period of time. Of the participants, only 8 percent reported their dogs vomited after eating grass.

UC Davis researchers conducted a second study, surveying 47 owners with dogs that regularly ate green plants and grass. Of the 47 owners, only four said they saw signs of illness in their dogs, and only six of the animals vomited.

Do dogs eat grass because their ancestors did?

Probably not.

Yes, thousands of years ago most canids preyed on herbivores (animals that consume mostly plants) and some of the prey’s vegetation found its way into the canids’ stomachs.

But was that amount of indirect plant food enough to create an instinctual craving in the modern domesticated dog? To test this idea, UC Davis scientists devised a method for measuring the plant content present in the diet of the closest surviving link between the modern dog and its undomesticated ancestors: the wolf.

When they examined the feral wolves’ stool samples, 11 to 47 percent of the gathered droppings contained grass. Since pack animals consume primarily raw meat containing worms and other internal pests, some scientists believe wolves ingest the plant matter to purge intestinal parasites from their systems.

Although domesticated dogs still resemble wolves, their dietary needs are distinct.

During their domestication, dogs adapted to their human households and developed nutritional requirements similar to their owners. Many of the foods that benefit humans benefit dogs too.

Is it the taste?

Maybe.

Some veterinarians think dogs eat grass for the taste and texture, or perhaps because they are bored.

Dogs may enjoy the act of chewing, like humans with gum. After all, dogs have eatenstranger things for stranger reasons. Actually, eating grass is fairly common and usually nothing to fret over. (If your dog’s habit has become a pet peeve for you, train your dog incompatible behaviors—up, sit, come—using positive reinforcement and redirect his attention to something more productive.)

Does it indicate a dietary deficiency?  

Probably so.

Some canine dieticians claim that dogs crave grass because it provides a source of much-needed fiber, an indication of a nutrient deficiency in their regular diets.

Many dogs in the UC Davis experiment continued eating grass regardless of whether their meals were being supplemented with fruits and vegetables, and some researchers accept these results as confirmation that dogs aren't eating grass for nutritional reasons.

However, the supplemental plants in the study (while high in fiber) may have been lacking the high concentrations of chlorophyll found in grass, and many leading holistic veterinarians believe dogs eat grass primarily for this nutrient.

A fat-soluble pigment, chlorophyll gives green plants their color and aids photosynthesis.

When ingested and digested (as part of the diet), chlorophyll attaches to cancerous compounds and inhibits cancer’s development. Dark, leafy greens (especially spinach leaves), green beans, green peppers, broccoli, asparagus, zucchini, cucumbers, green apples, kiwi, and honeydew are rich in chlorophyll and are healthy additions to a dog’s regular diet.

Common Sense

Thankfully, eating grass in moderation isn’t detrimental to a dog’s health.

Whether he’s savoring the taste, easing a queasy stomach, smacking on a lingering instinct, or going green for good health, your little four-legged lawnmower is probably just fine.

Although more studies are needed to determine the exact cause of grazing, feeding a balanced diet rich in colorful fruits and vegetables is always a safe bet.

Does your dog eat grass? Tell us about it.