Now that you mention, I used to see white dog poop up until the late 90s but I can’t recall the last time I saw it. I think other countries (southern hemisphere, anyone?) phased out meat and bone meal later than US.
Fortunately I don’t recall my family dogs passing white poop at that period, so I think at least we fed them with good quality food.
This is what I was going to say–that there’s no white poop around because people don’t leave their dogs’ poo lying around for weeks at a time anymore. I’ve certainly seen dried-up white canine poo (probably from coyotes) out in the wilds. Maybe they eat more calcium? Or maybe they just don’t have a pooper-scooper.
A part of me is a little nervous that with this factoid circulating, if it were go viral enough, would push dog food companies to market food based on making tidier, easier to collect poop (rather than actual mutritional value…)
Just an aside: About 15 years ago, US comedian Sarah Silverman (and her sister) sang a very-short song called "(Whatever Happened To That) White Dog Poop From the 70s. I think it was from her show on Comedy Central.