There are many theories. However, in our opinion, dogs take grass in two different ways. Firstly, they will take one or two pieces of coarse grass which will then stimulate retching. This may well result in the grass being thrown out, amidst a pool of white or yellow frothy liquid. This could be the dog’s way of relieving pain, caused by stomach acid that has got ‘too strong’
Secondly, from late spring to early summer, many dogs appear to ‘graze’ relatively large amounts of grass, and do not vomit. We believe this may be the dog being aware of the rich nutrients and trace elements present in vigorously growing grass. The dog cannot digest the grass structure as it is made of cellulose. However it may get some nutritional benefits from the contents of the grass.