Screaming or howling in Linn County, Oregon

It was the middle of the night and I was woken up by the dogs barking, I opened my bedroom window and yelled "shut up" and when I did something screamed, I mean SOMETHING SCREAMED - I have never in my life heard what I had just heard. I went to get my husband up as he had fallen asleep on the couch that night. I was in the living room and could hear the dogs barking frantically in the back yard which is backed up to a mountain. I opened the window to call the dogs back and heard what ever it was moving along the back side of the yard. It was a definitely a very large animal by the sounds it made while running. I yelled for the dogs and what ever it was stopped and I could hear it breathing. It was a raspy sound and very close. It was too dark to see but Im sure it was stopped looking back at me from a distance of approximately 75ft. It then ran up the hill. By the sounds of its running I'm convinced it was on two legs, not four and that scream was nothing I had ever heard before or ever want to hear again. My family has been hunting my whole life I know what a cougar sounds like and a bear and elk and what I heard that night was none of those. We live on six acres backed up to a mountain range also we are within 5 miles of the cascades. I believe in my heart bigfoot was in my yard that night. Also we found footprints on top of the mountain several months later that I photographed but I did not measure properly for which I kick myself for being so stupid. The prints were huge, at least 18 to 20 inches long and when you put your hand down in the print you could feel where the toes and ball of the foot were. What ever made these prints was very large and heavy. I can scan the pics and email if you want them.