Screaming or howling in Polk County, Iowa

about 2 or 3 a.m. I was awakened by my st. Bernard puppy who was quite upset. I soon learned why as I could hear my neighbors 2 dogs, a great Dane and a husky by the back of our house crying loudly. I was almost 14 at the time and was quite scared by the commotion as was my puppy. I looked out my window towards the cornfield and swamp behind the house but saw nothing but the dogs staring out towards the swamp, they started to go back out to the darkness in full attack mode. they weren't even barking but like screaming at whatever it was out there. I then heard a large rustling sound in the dried reeds by the fenceline. It sounded as if the dogs had been hit and they ran back to the safety of our back porch light. I ran to Moms room but found her at our back kitchen window staring towards the commotion. When the dogs would silence a little we could hear something walking in the reeds. It sounded very heavy like a cow but made no sound other than the walking noise and extra commotion when I believe it defended itself against the dogs. My neighbors across the street also watched from their front porch as this event continued for about an hour. Myself and my friend looked the area over from the safety of our dirtbikes about 3 days later as we were too scared to go out there after what happened. We saw reeds smashed down most of the length of the fenceline and what looked like a deer lay but it was way overgrown and would have been tough to leave a footprint that would be identifiable to a couple of young kids. Just after our incident, maybe a couple of weeks later I remember seeing on the news about a bigfoot sighting at the Cherry Glen campground not too far from our house. Also sightings in the Adel Iowa area the previous November that also made the news. We do not know what was out there that night but my mother remarked how funny it seemed to happen in between two sighting occurences in the area. The swamp is now mostly developed into a housing area nestled in between Saydel High school and n.e.60th avenue in saylor township. I thought this story which is quite well known among my old school buddies would maybe complement the other stories in central Iowa at that same time. Its not dramatic or filled with terror but it sure shook me up for a couple of weeks after as me and my friend were sure it was bigfoot. We never looked at that gloomy old swamp the same way again.