A compound of formula: wherein Ar, Ar1, Ar2, R3, R4, R5, R6, R13, m, t, and x are disclosed herein, or a pharmaceutically acceptable salt thereof (a “Hydroxyiminopiperazine Compound”); compositions comprising an effective amount of a Hydroxyiminopiperazine Compound; and methods for treating or preventing pain and other conditions in an animal comprising administering to an animal in need thereof an effective amount of a Hydroxyiminopiperazine Compound are disclosed.