Boredom
When a dog is bored, they look for things to occupy their time. This could be in the form of eating leaves or digging holes; anything to occupy their time. To keep your dog from experiencing boredom switch out their toys weekly so they always have “new” to play with. Look for toys that are interactive and will keep them thinking and trying to figure out the puzzles. Ensure they are getting plenty of exercise and tailor their activities to their breed. For example, a Border Collie enjoys herding and patrolling while a hunting dog likes to be scenting and retrieving.
Nutritional Deficiency
Commercial dog foods range in quality of ingredients. Most commercial dog foods will also contain fillers that have no nutritional value. However, most are nutritionally complete. Issues can arise however, if your dog skips their dog food in favour of human snacks and treats.
If your dog is not getting enough nutrients from their food, they will look for other sources to fulfill that need. By eating leaves, they could be signaling that they are not getting enough fiber or other important nutrients. Speak with your veterinarian about which dog food would best meet your dog’s nutritional needs.
Nausea
Dogs will munch on grass and leaves as a way to alleviate nausea. Many times you will see your dog chomping on leaves and grass and them vomiting. They will eat the leaves and grass to induce vomiting and hopefully help their nausea. Recurring nausea could be a symptom of something serious and should be checked out by your veterinarian.
Gas
Gas is a sign of gastrointestinal upset and if your dog is feeling bloated or gassy they will try to alleviate the uncomfortable sensations they are experiencing. They will do so by eating leaves or grasses and making themselves vomit or have a bowel movement. Gas can occur from a change in their diet. Treats or food can give your dog gas and bloating and cause them to feel uncomfortable and lethargic. Excessive gas can cause your dog to be miserable and it is a good idea to see your veterinarian quickly for treatment.
Intestinal Parasites
It is believed that your dog will eat leaves as a way to help eliminate intestinal parasites. Dogs that are suffering from an infestation of intestinal parasites will, in general, not feel well. They will eat leaves as a way to alleviate any stomach upset and to try and flush the intestinal parasites from the intestinal tract. If you notice worms in your dog’s stool or vomit, you will need to seek medical attention immediately. However, worms aren't always visible. This is why routine dewormer is advised for all pet dogs.