Dog in grass
Dog in grass

If you’re like most dog owners, at some point you’ve probably seen your dog chewing on grass like a cow.  ***Spoiler alert***  Nobody really knows why they do this.  That said, there are some intriguing theories for reasons behind this behavior.

Theory #1: Nutritional Deficiency

This is probably the leading theory I’ve heard.  If your dog is missing something in his diet, he may have to forage beyond his usual food sources to fill in the gaps.  Eating poop.  Eating grass.  They may be attempts to make up for a lack of nutrients.

Where’s the proof?  At this point, proof for this theory is not definitive.  Recent studies were inconclusive so this theory is unproven.

Theory #2: Induce Vomiting

Another theory is that dogs eat grass because they’re not feeling well and are trying to throw up.  Recent studies with 1500+ dogs showed that less than 10% of the canines that ate grass had any symptoms of illness before ingesting it.  After eating grass, less than 30% of the dogs actually vomited.  SO, this theory should also be marked as unproven.

Theory 3: Parasite Elimination

Some think that because grass is fibrous it could theoretically help eliminate intestinal parasites from the digestive tract.  Believers in this theory think that grass could be a natural means to get rid of these parasites.  Unfortunately, there also seems to be little proof of this theory.

canine, dog, pet
Canine instinct

Theory 4: Instinct

Why do animals behave in certain ways?  Instinct seems to be behind much of their behavior.  So it’s not surprising that instinct is another theory for the grass-eating behavior of dogs.  It’s just another one of those habits that got passed on from their ancestors.  Maybe like a dog circling a spot multiple times before lying down.  Although unproven, there may be something to this theory.  Domesticated dogs do seem to be able to live on diets containing plant material in addition to meat.

Theory 5: Fun?!

Could it be that dogs just enjoy eating grass?  Not sure how this one would be proven, but perhaps eating grass provides a sense of pleasure to our canine companions.  Maybe eating grass is like getting scratched behind the ears.  Perhaps it just makes them happy.


So there you have it.  Five unproven theories on why dogs eat grass.  Will we ever really get to the bottom of this behavior?  Time (and research funding) may tell.

The good news is grass-eating isn’t necessarily something to be worried about.  However, if symptoms persist, or you see your favorite pet feeling ill after eating grass, this may be a signal to visit your vet.


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