Cow horses begin training early in their second year, and may be shown in a three year old herd class early in their third year. Those horses showing exceptional ability and maturity may be shown in local or national futurity classes toward the end of their third year.
Two year olds are started in the snaffle-bit. This allows lateral control allowing the rider to direct (pull) the horses nose in the desired direction. The snaffle-bit is used two handed with split reins.
Horses that are competative in the futurity classes exhibit exceptional qualities as three year olds. The futurity classes are a huge demand on such young horses. The rewards can amount to huge payouts.
Young horses continue to mature, grow and become more proficient at the cow horse events. The best are again tested in the derby. Identical to the futurity except for four and five year old horses.
Derby horses can be show in either the snaffle-bit or the hackamore.
Hackamore horses are also four and five year olds that are shown in the hackamore competing against other horses also shown in the hackamore. The Hackamore class provides an opportunity to show horses that may not be mature enough to compete in the derby classes. However nothing prevents a horse from being shown in both the derby and the hackamore classes.
The two-rein class is usually considered a transition class used to introduce an aging horse to a bridle while allowing the rider the ability to direct the horses nose in the desired direction, using a smaller version of the hackamore.
At six most horses have grown to their full size and weight, they've become much more mature and confident in their jobs. Six year olds are ridden in a bridle using romal reins.
The bridle spectacular class is exactly like the bridle class but with the inclusion of a herd work event.