Dogs.

I don't know. But our dogs also eat the feces of their youngs. Maybe that their nature.

I can pull one factor off of the top of my head. When a dog eats too fast, the food doesn't get digested as well as if they ate it more slowly. So, the smell of their feces will more closely resemble the smell of their food, adn they will turn around and eat it. As a previous response said, it is because of a lack of nutrients. It could be partially due to the food that they are eating, but in a lot of cases, it is because the dog is eating so fast, it doesn't digest, and, because of that, they get nothing from their food.

Oh my. I have heard of dogs eating their own excrement but never heard of a dog eating another dogs excrement. I have been told by the vet, that dogs will eat excrement because they are lacking things in their daily nutrition.