Many people think that when their dogs tear at the ground with their back feet after they have urinated or defecated that they're trying to cover up the mess, just as a cat might. This is not true. What the dog is doing when it scrapes frantically at the ground is symbolically marking the territory; “Ollie was here,”
The deposition of urine and faeces can represent a territorial mark not only for dogs but also for just about all domestic species. So when a dog finds just the right place and he performs his duty, he finishes by scratching the ground in the immediate vicinity with his hind feet to leave his calling card.