It's likely gone because a) it gets cleaned up long before it ever has a chance, and 2) because dog food is far better quality today than a decade ago.
Imagineer, have you been reading www.80snostalgia.com again?
If you miss white poo go on safari. Hyena poo is white and chalky because they tend to eat the bones right along with the meat! Niiiiiice! One of our guides even picked up a hyena turd and passed it to me and I accepted it before realising I was holding "DOG" POO!!!!
Kavey's exactly right - it's the calcium from the bones that they used to grind up along with the other 'parts' that went into dog food (like hot dogs...it was mostly ass and lips).
