Your skill at handling horses allows you to influence all the horses in the area.
Benefit(s): You gain a +2 bonus on Handle Animal and Ride checks to handle or ride horses. In addition, you can attempt one Handle Animal check to issue a command to all horses within a 60-foot radius. An opponent whose animal companion or mount is within range can attempt a DC 20 Handle Animal check as an immediate action to prevent her horse from being influenced by you. If the opponent succeeds, you cannot influence that creature again for 1 hour.
Pathfinder Roleplaying Game Adventurer’s Guide © 2017, Paizo Inc.; Authors: Benjamin Bruck, John Compton, Crystal Frasier, Tim Hitchcock, Jenny Jarzabski, Isabelle Lee, Joe Pasini, Jessica Price, David Schwartz, and Josh Vogt.