Untitled Sighting

About 0035hrs I woke up. I don't know if a sound awakened me or if I just woke up. {Light sleeper.} All was quite outside. From out at the edge of the field There was a howl unlike any I have ever heard. It was 5 seconds with about a 3 second pause and another burst for about 5 seconds. As soon as the sound quit, The dogs erupted in a howl. We have 14 sled dogs. During the spring we get beaver carcasses from some local trappers to cut up and feed to the dogs. The entrails and bad carcasses go out into the woods for animals and birds to eat.We have been doing this for five years. The day after the sounds I went out into the woods to look for tracks but did not find anything. Under a tree there were the stripped carcasses of three beavers and the skeletons were stacked all facing the same way. Could just be a coincidence. No further incidents this spring.