Why is your cats poop green?
It is probably sick:(.........get it to the vet as soon as possible!
Green poop can be dangerous in massive amounts. If you poop once a day for a week and you have green poop 3 out of the 7 days, that's fine. But if you take a poop and plug the toilet with green poop than that is too much. You might want to get yourself checked for the swine flu cause you probably have it
Have you changed their diet? Have they been sick? Have they been on antibiotics? All of these can effect their defecation color. My cat was sick and had tarry red diarrhea, but we got her on antibiotics and it turned green. Also, most of the time green feces normally mean that iron is not being absorbed from the food or an increase in iron intake. It depends.
Poop (feces) are the waste products of digestion and certain parts of cell respiration. The food people and animals (including cats) eat is not completely utilized in the digestion process and it passes out of the intestinal tract in the form of poop! The less efficient the animal at digesting it's food the more feces it produces...that's why cows, horses and other animals produce a lot more poop than other animals.