It can be yellow-green, brown, black, or a mix of those colors.
Actually your pup/puppies can be having bowel movements and you may never see them until ( 2 - 3 weeks ? ) which may cause you to ask do they have bowel movements. ( thinking drinking mom's milk only...
its called corophagia. quite normal for puppies to do this. it is believed that they are lacking a protein found in feces
dark brown :-)
I think that you have cancer... that is a sign.