Most dog owners will have noticed that at some stage their four-legged companions take a munch on a bit of the green stuff. As to the why, well that’s a source of a lot of speculation but not a lot of scientific study.

Certainly, some dogs who appear to have a digestive upset seem to seek out grass either to make themselves sick or simply because they feel sick and the result is an often instant expulsion of stomach contents. The often-touted theory then is that dogs eat grass to deliberately make themselves sick. However, this doesn’t hold up under scrutiny, as it has been noted that many dogs eat grass without making themselves sick. In fact, where studies have been done, it appears that less than 25% of dogs that eat grass are actually sick so – for the majority of dogs – grass eating is not directly associated with vomiting.

The next suggestion is that it is some sort of doggy desire to supplement the diet with something that is lacking, either in the form of roughage, fibre or some other trace mineral or nutrient. It is proposed that wild canines would eat the gut contents of their grass-eating prey and domestic pets are simply replicating a part of the diet that is lacking in commercial dog foods. However, this seems to also fall down under scrutiny, as dogs supplemented with extra fibre in the form of vegetables and fruit in their diets will continue to voluntarily eat grass.

Maybe they just like the taste of it!
It does seem that there is something in dogs’ DNA that makes them seek out grass. Research on wolves’ droppings shows grass in 11-47% of samples. Clearly there must be some innate desire that dogs are born with. One theory that might be plausible is that grass could help to cleanse dogs’ intestines of internal parasites. As long grass fibres pass through the intestines they wrap around and clean out worms and helminths from the guts.

Of course, if you are worming Fido every three months (like you should be), the grass is fairly redundant. But at the end of the day eating grass seems to be a normal and largely harmless activity and who knows – maybe dogs just like the taste of it!