When I was growing up, white dog poo was a common sight. Nowadays it's as rare as rocking horse poo (almost).
There are many theories as to its disappearance from our streets and parks; a quick search on google comes up with thousands of discussions and websites dedicated to this nostalgic excrement. It even has a growing number of Facebook pages! Some say that dogs these days have a different diet, thus depriving us of these cherished turds. Others firmly believe that white dog poo is created by the bleaching effects of the sun, and that it must now be less sunny than in the 1970's.
Whatever the reason, keep your eyes peeled for these retro random things, and don't be surprised if you ever see some come up on Ebay!