I know dogs can eat some greens/vegitables and they can be good for them in certain things but they are STILL natural carnivores. Their sharp teeth proves that they are built to tear apart flesh and hunt.
Depriving them of those important nutrients WILL be detrimental to their health, same thing applies to cats. I wish more vegans understood this instead of being most likely being vegan just to feel supurior or act liek they have a say in other people's diets.