There is a documentary out there about the coy wolf. I found it on Netflix a while back. According to it, back east the coyotes and wolves do interbreed, but that it is due to the eastern gray wolf, for some reason. Has only occurred in that area, and that particular strain of wolf.
About coyotes and dogs crossing, I have seen evidence that it happens, but just my observation.
I knew a fellow in Alaska who called me to look at an animal that he had trapped. This was in the '70's. Asked me if it was a coyote, or dog. It appeared to be a coyote/collie cross. There was a family who lived nearby, who had collies, and that darned animal looked like exactly what you would expect from that combination. Definitely had coyote ears, but the rest looked dog-like....enough so that he didn't bother to skin it. That was on Schrock/Pittman road, Mart.
Two other times in Alaska I came across animals that looked something like a wolf, but not quite right. One of these was in the early sixties, the other in the seventies...but the same area, and both animals could have been twins. Close to being a wolf, but not close enough to skin. That was pretty wild country back then, too. Talkeetna mountain range, Bald Ridge.
Just what I observed, and after all this time, I still don't know.