My experience suggests that dogs do this for two main reasons: they’re using it to purge their bodies of something (food that disagrees with them, or something they’ve ingested that may, or may not be food), or they’re searching for something to do, and perhaps enjoy eating. In other words, the dog may find this behavior entertaining, relaxing, or even nutritionally beneficial. You can tell which of the two a dog is experiencing by watching the way they go about eating it.
Frenzied behavior that leads them to eat whichever grass happens to be closest to the door you’ve let them through (often because they seem to have an urgent need to get outside), and vomiting afterward can be due to a health problem, or is a sign of the diet not agreeing with the dog. If it happens often, and the vet has given an all-clear, it may be time to take a 3 pronged approach:
1. Consider changing the food to something the dog has never eaten before, preferably something lean. The idea here is that the dog may not be tolerating the food itself and/or have developed an intolerance to the fat content of that food. By choosing something lean that the dog has never consumed before, you’re addressing both possibilities.
2. Digestive enzymes are positioned to help digestion. Clearly, a supplement can be very helpful to those dogs who need it.
3. Acidophilus, more than other probiotics, is a natural part of the healthy dog’s GI population of good-guy bacteria. Adding a supplement to your dog’s diet can have a very positive impact.
The recreational chewing of grass may or may not have a root in nutritional causes as well. Nobody knows. Typically, these dogs are selective in their snack. They sniff out certain grasses in particular locations which might be due to that grass simply tasting better, but what if that grass offers something more? Can it be that the dog is searching for greens, and the addition of some leafy greens in the diet helps to curb the behavior? I’ve seen this often! I’ve also seen dogs reduce, or stop the behavior when alfalfa powder was added to the diet. If the dog is eating safe grass (not sprayed with chemicals), his/her preference to eat it now and then isn’t a worry. But if you want to make it stop, finding the right green food to include in the diet can be really helpful.
Read more about why dogs eat grass here