Why Do Dogs Eat Grass?

Picture the scene, it's a lovely summers day and you're out for a walk with your Dog...

Well at least you were out for a walk with your Dog until you realise the Grass has suddenly become more interesting to him than actually keeping up with you. Yes it's happened, suddenly you've become second best as he tucks into his second mouthful of Grass.
By now you're looking on horrified wondering why your Dog could be doing something so crazy! I mean, why would be do it? Surely he's going to make himself ill eating grass and spend the rest of the walk home vomiting right?

Well if you listen to what people generally have to say on this subject, most seem to follow a particular pattern suggesting it must be something to do with the dog being poorly, having an upset stomach and simply eating the grass in order to vomit. Others suggest that it something to do with the Dog having worms and the Dog is merely eating grass to try and clear the intestine of these worms. It's a nice idea, but don't give up on those Dog Worming Tablets just yet.

However, nothing could be further from the truth since if you have a dog yourself and you freely allow it to eat grass. Chances are it will only eat a small amount and then go about it's day as normal. No vomiting, no ill behaviour and no signs of illness from your Dog or the one you've been watching from across the way in the park. Even if the dog was to vomit on one of those rare occasions, it wouldn't have been intentional.

So if it isn't because they have an upset stomach, why do Dogs Eat the damn Grass you're asking...

Quite simply... Nobody knows 100% for sure why they do it, but there is a popular consensus amongst experts as to why they do it. I'm happily siding with their opinion since they've had books published. So here goes, a round up of all the information I have gathered up all in one place.

Quote from Applied Animal Behaviour Science (Original content removed so I've linked to the Google Cached version in the 'Links' section at the end.):
Using an internet survey targeting owners of plant-eating dogs, we then acquired information regarding the frequency and type of plants eaten, frequency with which dogs appeared ill before eating plants and frequency with which vomiting was seen afterwards. Of 3340 surveys returned, 1571 met enrolment criteria. Overall, 68% of dogs were reported to eat plants on a daily or weekly basis with the remainder eating plants once a month or less. Grass was the most frequently eaten plant by 79% of dogs. Only 9% were reported to frequently appear ill before eating plants and only 22% were reported to frequently vomit afterwards

So what can we see from the results of this survey? Well for a start, if your Dog eats Grass (or plants in general),  you shouldn't be alarmed as 79% (1241 owners) of the 1571 respondents have reported similar behaviour in their Dogs. Then of the 79%, only 9% (112) reported that their Dogs frequently appeared ill after eating grass. The report doesn't go any further to explore why their Dogs are ill as a result of eating the grass. Just like with humans, it could be something as simple as over eating, binge eating on the grass or even just something as simple as the Dog getting heart burn, indigestion or something similar. Nothing different to humans who suffer from the same sort of affects if they eat certain foods.