SRD:Light Warhorse

Light Warhorse
Horses are widely domesticated for riding and as beasts of burden.

These animals or similar to light horses but are trained and bred for strength and aggression. They usually are not ready for warfare before age three.

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

Combat
A horse not trained for war does not normally use its hooves to attack. Its hoof attack is treated as a secondary attack and adds only half the horse’s Strength bonus to damage. (These secondary attacks are noted with an asterisk in the Attack and Full Attack entries for the heavy horse and the light horse.)

A light warhorse can fight while carrying a rider, but the rider cannot also attack unless he or she succeeds on a Ride check.

See Wikipedia Entry:
 * Horse
 * Horses in Warfare