It's a light war horse. Or a riding dog for small folk.
Light War Horse Large Animal; CR1; HD 3d8+9; hp 22; Init +1; Spd 60ft; AC 14 (touch 10, flat-footed 13); Atk +4 melee (1d4+3, 2 hooves), +1 melee (1d3+1, bite); Face/Reach: 5x10/5; SQ Scent; AL N; SV Fort +6, Ref +4, Will +2; Str 16, Dex 13, Con 17, Int 2, Wis 13, Cha 6.
Skills and Feats: Listen +7, Spot +7
Possessions: bit and bridle, military saddle, saddle bags, rations x7, waterskin x7
Riding Dog Medium-Size Animal; CR1; HD 2d8+4; hp 13; Init +2; Spd 40ft; AC 16 (touch 12, flat-footed 14); Atk +3 melee (1d6+3, bite); SA Trip; Face/Reach: 5x5/5; SQ Scent; AL N; SV Fort +5, Ref +5, Will +1; Str 15, Dex 15, Con 15, Int 2, Wis 12, Cha 6.
Skills and Feats: Listen +5, Spot +5, Swim +5, Wilderness Lore +1 (+4 when tracking)
Possessions: bit and bridle, military saddle, saddle bags, rations x7, waterskin x7