These are fun games to play for sure. Initially couldn't tell between deer/coyote due to it being by itself, I am sure if there were deer and coyote you would have been able to tell, but a pack of yotes and a herd of doe wouldn't have helped much if they were all standing still.
Once it started moving it was pretty easy to see it was a dog, but as mentioned, no way to get a good shot as it never stopped and then went into the brush.
Standing animals can be tough, but you get a quick read on them based on their Movement, speed, and travel tendencies. I can pretty reliably pick out hogs from cows from a long way away just based on movement. Coyotes and fawns or line deer can be tough esp in thicker grass where you might not see anything but body and head. Usually behavior is the telling sign here, and how they move. Coyotes trot and deer walk or leap for the most part.