I've seen cuts like that from dog fights. I've also seen cuts like that from sticking the snout under a fence and catching it on a backwards facing wire or nail while drawing the head back out.
The only thing I can think of that would make a wound that large from sticking the head down a hole would be a badger, and I suspect a badger would leave more than one cut. A badger will tear a dog up.
Large predators would leave more wounds than that and they wouldn't come back after getting whupped by a pack of dogs.
Have you felt the entire dog, under the fur, to see if there are other wounds or puncture marks?
The only thing I can think of that would make a wound that large from sticking the head down a hole would be a badger, and I suspect a badger would leave more than one cut. A badger will tear a dog up.
Large predators would leave more wounds than that and they wouldn't come back after getting whupped by a pack of dogs.
Have you felt the entire dog, under the fur, to see if there are other wounds or puncture marks?