Variations in breeds used, include mountain ponies from the Himalayas, Manipur ponies from Assam, Arabians and the ever popular Thoroughbred and its crosses. In the United States, Thoroughbreds and Quarter Horses are often crossed to make polo ponies, while in recent years crosses of Thoroughbreds and Criollo horses from Argentina have become popular. In Australia, Australian Stock Horses are the commonest breed to be used in polo.
During the early 20th Century in the United States a polo breed association was formed, complete with a stud book. The principal foundation sires were Thoroughbred race horses of small size.
Polo ponies have their manes hogged before a match and their tails are plaited up. This is done so that the polo mallet will not get tangled. Formerly, their tails would be docked and banged. Today, polo ponies in competition often have their dock trimmed or shaved, and the skirt of the tail is braided and folded up against the tailbone. The braid is tied off with a lock of hair excluded from the braid, or taped, or both tied off and taped.
There are several different quarters in a game and so each rider has one or two horses per quarter, called chukkas. There are usually 4-6 chukkas per match, each lasting 7 minutes.