Dogs are one of the easiest pests to deal with because they don’t climb or tunnel, and they are too big to fit through cracks and small holes.
OP you just have to protect your pile more. I suggest a hoop of metal cloth for something cheap and simple. Geobin is a similar idea and cheap.
I’m not saying a determined dog couldn’t break these down but they provide enough discouragement to make it unworthwhile for a well fed dog to mess with.