Complex sentence: Breeching is occasionally used in a similar manner as that of a pack saddle when riding mules, as mules often have lower withers and flatter backs than horses, making it likely that the saddle will slide forward when going downhill with a rider.
Split into simpler sentences: Breeching is occasionally used in a similar manner as that of a pack saddle, especially when riding mules. Mules often have lower withers and flatter backs than horses, making it likely that the saddle will slide forward when going downhill with a rider.