CALVIN

CALVIN
CALVIN - THE KING

Wednesday 20 October 2010

WHY DOGS EAT GRASS?


These summer days, when I take my German Shepherd Calvin for a walk, he always wants to stop and eat grass. Not just any grass. The leaves have to be the right size and shape. Although there are other grasses nearby, he always heads for wheatgrass (Agropyron), with its broad green leaves.
I have read that dogs eat grass because they want to vomit or because they are having digestive troubles.
Calvin hates to vomit. He will do anything to keep from vomiting, so that doesn't seem to be the answer, at least as far as he is concerned.
I feed him premium dry food, and he digests it very well, with well-formed stools. Digestive troubles do not seem to apply to Calvin either.
So because the two explanations I have read do not seem to be relevant to Calvin, I decided to dig a little bit into the scientific dog literature to see what I could find.
Surprisingly little has been written in scientific journals about why dogs eat grass.
One recent study approached grass eating in dogs with the hypothesis that grass alleviates digestive distress (McKenzie et al. 2010. Reduction in grass eating behaviours in the domestic dog, Canis familiaris, in response to mild gastrointestinal disturbance. Applied Animal Behaviour Science 123: 51-55).
In that study, the authors fed dogs a diet that produced loose, watery stools, to mimic a condition of a mild digestive upset. They also fed the dogs a standard diet that produced normal stools, and gave the dogs two types of grasses to eat during each experimental condition.
The results were that the dogs ate more grass when they were fed a standard diet than when they ate the diet that caused the digestive upset. So much for that hypothesis.
Then there's vomiting.
I found a study that looked at whether dogs vomit more when they eat grass (Sueda et al. 2008. Characterisation of plant eating in dogs. Applied Animal Behaviour Science 111: 120-132),
In that study, the authors surveyed 1571 dog owners on the internet and found that 79 percent of the dogs ate grass, and of these, only 9 percent were sick before they ate the grass, and 22 percent vomited after eating the grass.
These results show that the vomiting hypothesis doesn't seem to hold any water either.
So why do dogs eat grass?
Ask yourself that question the next time you eat a luscious salad.
My guess is......because it tastes good.

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