The reason for the disappearance of white dog poop, however, is less obvious. It wasn't a product of your young imagination: Chalky, white dog poop really was everywhere in the 1970s and '80s. According to Treehugger, the culprit behind the white dog waste of the past was a surplus in calcium. It's still possible for dogs to get too much calcium in their diet in the 21st century, so white dog poop hasn't gone away for good. White specks in dog poop could be a sign of a more serious problem like worms.