If you were around in the 1970s or 1980s, you most likely remember white dog poop — it was so commonplace, nobody even questioned it. At least not that I can remember from my childhood. There was the brown variety and the white variety of doggy doo-doo, end of story. But now that the milky muck is no longer around, it seems awfully strange that white poop ever existed. In fact, I'd forgotten all about it until I ran across an article this morning by the Animal Rescue Site, which pointed to dog food ingredients that were popular at the time as the culprit:
Back in the 1970s, it was common to feed dogs food that was extremely high in calcium from cheap bone meal and meat. Since dogs couldn't process the amount of calcium they were consuming, they would simply poop out the excess!
As the sun dried the feces out, the white calcium would become visible – which is why dog poop was often viewed as white.
I couldn't find an in-depth article as to what caused the demise of chalky canine chunks, but there's this, from the not so scientific IFL Science:
Once upon a time, dog food was stuffed full of calcium-rich meat and bone meal. The mineral is good for dogs to a point, but there's a limit to how much can be processed, and how it is rendered alters how absorbable it is. Like humans who take too many vitamin supplements and end up making expensive urine, dogs given too much calcium can sometimes simply push it out of their rear ends.
White dog poop wasn't what came out of their butts, however, as the snow white hue wasn't usually revealed until it had been left out in the sun to bake a little. As the water evaporated, calcium stuck around, leaving a peculiar pile of white dog poop cased in a mineral veneer. …
One thing that's been generally accepted across the board, however, is that bulking up commercial pet food with cheap bone meal isn't the best option for our pooches. As such, fewer dogs are reaching the hard-to-digest calcium surplus that they were back before the turn of the millennium, and now dog turds left baking in the sun stay looking like, well, dog turds.