Canis lupis-Grey Wolf tracks ?

The other night, our dog went crazy barking loudly at the window in the middle of the night. The next morning- there were a few tracks outside in the pea gravel, twice the size of our dog's paws. Here is a photo of one with our dog's track barely visible next to it. It is heavier than he is and he weighs 120 lbs. It also has long claws- so it is not a cat, as the big cat tracks have paw marks without signs of the claws. It is my understanding that it could be a grey or possibly a red wolf, but it is not a coyote, as they are much smaller and lighter. To find out more about the wolf in America-click on the title above. The sound file sounds alot like the howls that we hear on occasion in winter. I'll keep you posted if I see more.