Snow is notoriously difficult to read tracks, unless they are steaming fresh. A mud print would be the best bet. Dogs tend to have the middle two phalanges extend past the outer two, and of course the cat family has retractable nails.
Reading tracks has been my profession for the last 24+ years - mostly human tracks, but the principles are the same.
FWIW - coyotes poop in the middle of the trail/road to mark their territory. Foxes poop on top of rocks and logs. Cats cover the scat.