The road not taken
A donkey or a mule is a pack animal ideally suited for carrying heavy loads. I have modified the stats of a Light Horse to reflect this (reducing speed from 50 ft. to 30 ft., increasing Constitution from 17 to 18 and swapping the Run feat for Pack Mule). A donkey or mule costs 75 gp and weighs about 600 pounds.
AC 11, touch 11, flat-footed 9 (+2 Dex, -1 Size)
Fortitude +7, Reflex +5, Will +1
Melee 2 hooves -2 (1d4+1)
Space 10ft.; Reach 5 ft.
Base Atk +1; CMB +5; CMD 17 (21 vs. trip)
Feats Endurance, Pack Mule
Skills Perception +8
Special Qualities Docile: Unless specifically trained for combat, a donkey’s hooves are treated as secondary attacks. Carrying capacity Light load 0-399 lbs; Medium load 400-798 lbs; Heavy load 799-1200 lbs