You cannot use shape or anatomy to prove, once its been mounted. It could, in theory, be a dog skin on a coyote form, thus nullifying anatomy. But to me, two things give it away. Long hair between the toes, unlike a domestic, and the tail. Thats a coyote to me. I see lots of coyotes with that color phase, I dont think Ive seen a dog that color. Also, long nails seem wild to me.