It is not uncommon for dogs to eat grass. Although the reasons are not clear there are several possible explanations that have been offered for this behaviour.
One explanation suggests that as wild canids (e.g., wolves and fox) eat all of an animal when they catch it (and their prey are commonly herbivores or
plant-eating animals), they end up eating a lot of grasses and plants that were in the intestines of these animals. Also, wild canids have been known to eat certain berries and other plant material, so it is suggested that dogs eat grass because it is a part of their normal diet.
Many people will observe that their dog will vomit after eating grass. However it is uncertain whether they eat grass to make themselves vomit or whether they vomit because they have eaten some grass. Some dogs may eat such vegetation when they have an upset stomach.
However, it is probably that these dogs eat grass simply because they enjoy the taste and purposely seek it out for pleasure.
Essentially, grass eating is a normal behaviour, and is not a concern unless your dog does it excessively or this is a sudden change in your dog’s behaviour. If you are concerned, we would recommend that you discuss this with your vet.