** FOUND! I'm looking for a non-con in which one of the brothers (cannot recall which one - maybe Sam) is on his own, gets captured by group of men in a small town, is taken to a barn, is tied to a 'horse,' and repeatedly raped by multiple men.
His father and brother go back to find him and are told by local authorities he'd left town.
They may have encountered a chained man who warned them about what was going on (or, I could be mixing up my stories!)
There may have been bestiality with large dogs involved.
Sam's father and Dean (?) come to the rescue.
If there's more to it I can't remember.

Thanks in advance!