While searching for the Shaido in WoT Book 10 "Crossroads of Twilight", Perrin's group found that
a huge pack of Darkhounds - 50 or so instead of the usual 10 - had made a complete circle around their camp during the night and then continued on south.
Obviously the pack wasn't after Perrin, since they left. However, a pack that huge - a size not seen again until the Last Battle - must have been after something fairly important. However, I don't recall the pack being brought up again at any time afterwards.
What prey was the pack of Darkhounds searching for?