I can only speak to my experience, but my Cane Corso was very black when we got him at 8 weeks. He had a white marking on his chest, but for the most part black. We could notice a few little streaks of brown in one or two spots. Those streaks of brown are now much more prominent. They did not change, they just grew with him, and much smaller brindle streaks have shown up also. It is my opinion that the color does not change at all either way. It just grows with them. That is until they age.
I know dalmatians start white and get there spots, so this probably disproves much of what I theorize, but I think that is more the exception than the rule.
