Why does my dog have green stool?

A dog’s green stool may come from eating lots of green food, such as green vegetables, grass, fruit, or leaves. If the dog has no repeated soft stool or diarrhea, you need not worry.

But if the dog ate no green food and often passes green stool, it may have colitis or cholecystitis. Colitis releases acid that forms green biliverdin with bilirubin, turning the stool green.

Also, cholecystitis causes abnormal bile secretion, and excess green bile is passed with the stool, causing green stool. Take the dog to a vet promptly to confirm the cause.