“Dog sand” sounds to me like one of those euphemisms that make the thing sound even worse than it actually is. I feel the same way about “night soil.” Like whatever it is that you’re hiding with that euphemism, I am more grossed out by thinking about the ganular nature of it, and it’s even worse if the grain size is the main diagnostic feature of that substance.

Like you’re telling me that the dog made a pile of something and that it has a distinct location on clay-silt-sand ternary diagram? gross.