SRD:Mule

Mule
Mules are sterile crossbreeds of donkeys and horses. A mule is similar to a light horse, but slightly stronger and more agile.

Combat
A mule’s powerful kick can be dangerous.

Carrying Capacity: A light load for a mule is up to 230 pounds; a medium load, 231–460 pounds; and a heavy load, 461–690 pounds. A mule can drag 3,450 pounds.

Skills: Mules have a +2 racial bonus on Dexterity checks to avoid slipping or falling.

See Wikipedia Entry: Mule