Why does my dog eat grass?
Grass eating is common and, in most dogs, entirely normal. Surveys of owners consistently find that a large majority of dogs do it at least occasionally, and that the majority show no signs of illness beforehand and do not vomit afterwards.
The most widely repeated explanation, that dogs eat grass to make themselves sick when unwell, is not well supported as a general rule. The sequence is usually the reverse where it occurs at all: dogs that eat a lot of grass quickly may vomit as a consequence rather than as the goal.
More plausible explanations for routine grazing include simple palatability, since fresh grass has a taste and texture many dogs appear to enjoy; boredom, particularly in dogs with limited stimulation; and an inherited behaviour, as wild canids consume plant material including through the stomach contents of prey.
What is worth paying attention to is change rather than the behaviour itself. A dog that suddenly begins eating grass frantically, eats far more than usual, or shows other signs such as repeated vomiting, lethargy, appetite change or discomfort, should be seen by a vet. That combination is a reason to seek professional advice rather than to interpret at home.
Two practical safety points apply regardless. Grass treated with herbicides, pesticides or fertiliser can be genuinely harmful, so where a lawn has been treated is worth knowing. And some ornamental and garden plants are toxic to dogs, so a dog that grazes indiscriminately is worth supervising in unfamiliar gardens.
If the grazing appears boredom driven, more exercise and enrichment often reduces it.