How did these dogs get here? And, what are they all riled up about? (Is this in a sense normal? Would they usually act this way if let out at strange hours?)
Assume someone let them out. (Why would someone? Relatedly, who? On this party night, of all nights?)
Perhaps no one let the dogs out? (They escaped?)
Is someone sending us a message? Maybe we're being too loud. Are the dogs sending us a message? Oh, Timmy and the others! I don't think I've seen them in the hour since they went down to the river...