Someone just found this website with the search query "dogs with green poop". That's a problem I've not yet had to contend with, so I'm not sure why Google thinks the answers are here.
Not too long ago my housemate noticed that there was a distinct and unpleasant change in the potency of the smell of the dog's droppings. You have occasion to observe this sort of thing when you go on daily walks and have to clean up after a dog. Anyway, she was in a pet store talking to the clerk and commented on this stronger smell, wondering if they might know of something in the dog's diet that might have caused, or might remedy, the condition. The store clerk looked at her like this was the most unreasonable inquiry on earth and in a very polite and condescending voice said gently, "Unfortunately, there's nothing I can sell you that will make the poop smell like flowers, ma'am." So now we're always joking about how irritated we are that there's no additive that will make the dog's poop smell like potporri or flowers.