There is a scientific term for this, but I forget what it was. Basically the warmer the climate the smaller the animal will get. Big deer are able to stay warmer in the cold climates while the smaller deer can take the heat better in the hot climates. Aint got a thing to do with dogs running the deer. I dont know what some hunters will do when dog hunting is finally outlawed for good. They wont have nothing to blame everything on. JMHO!