Types of Horses

These rules are based on Robert Harrison's article "Let the horse buyer beware" from Dragon Magazine

Size Base Price Hit Dice Base Move* Damage/attack Carrying weight (pounds) 1d8
Draft 225 3+12 14" 2d8+4 Hoof/1d8+4 Bite 600/900 1-2
Light 50 2+2 24" 2d4+2 Hoof/1d4+2 Bite 300/500 3
Medium 125 2+4 18" 2d6+3 Hoof/1d6+3 Bite 400/650 4-6
Heavy 200 3+9 15" 2d6+4 Hoof/1d8+4 Bite 500/700 7-8
Quality Rating Price Modifier Hit Die Type Move Modifier* Carrying Weight 1d6
Poor -50% d10-2 (min 1) +(2d4-6)" -10% 1-2
Average 0 d10 +(2d4-5)" 0% 3-4
Good +100% d10+1 (max 10) +(2d4-4)" +5% 5
Excellent +200% d8+2 +(2d4-3)" +7.5% 6
Superb +400% d6+4 +(2d4-2)" +10% 7

*Take movement in inches and multiply by 2.5 to get movement in feet per turn. The warhorse in the PHB should have a 40 foot move.
Higher quality horses may be faster and have a higher minimum hit points. A character who makes a DC10 Animal Handling roll can get an idea of a horse's quality. DC15 roll lets them compare a group of horses to pick a better horse.

Training Type Cost (GP) Panic/Spell Failure 1d6
Riding +25 90% 1-4
Basic +100 40% 5
Skirmish +200 10% 6
Combat +500 3% 7

So a medium warhorse (125 GP) of Good quality (+100% of price or +125 GP) with Skirmish training (+200 GP) costs 450gp. If it was Superb quality (+400% or +500GP) with Combat training (+500GP), it would cost 1,125 GP.

Panic is the chance the horse will try to bolt when there is combat (smell of blood, screams, monsters or it takes a wound) and the chance that a spellcaster trying to cast from horseback will be jostled and the spell ruined. A horse that panics will move at full speed in a random direction away from the threat. Each turn the rider can make an Animal Handling roll to get the horse under control (Difficulty is based on the horse's training; DC20 for Riding, DC 18 for Basic, DC 15 for Skirmish and DC 10 for Combat). Druids or characters with the Mounted Combatant feat roll with advantage.

A horse with basic training will obey the rider's commands to charge and trample a man sized target (that uses the rider's Attack action). A skirmish trained horse will attack a creature that attacks it as well. A combat trained horse will attack targets in front of it by biting if possible or a hoof attack on its own action. If a combat trained horse's rider is unhorsed, make a panic roll. On a failure the horse will attack targets as it moves away. On a success, the horse will stand by its rider and attack creatures that approach.

For random horse generation, -1 in small towns and villages, no modifier for large towns and small cities, +1 for large cities. Horse Market