There are more than 350 breeds of horses and ponies. Each breed is classified into one of four groups: light horses, heavy horses, ponies and feral horses.
Light horses have small bones, thin legs and weigh less than 1,300 pounds. Morgans and Arabians are classified as light horses. Heavy horses, also called draft horses, weigh up to 2,000 pounds and have large bones and sturdy legs. Clydesdales and Belgian horses are breeds in the heavy horse category. Horses smaller than 58 inches are classified as ponies. Examples include Shetland and Chincoteague ponies. Feral horses are those that are wild or semiwild, such as the mustang.