Hunter hack is a type of English pleasure

English Pleasure

English pleasure is generic term for a number of different English riding classes seen at horse shows in the United States, where the horse is ridden in either hunt seat or saddle seat tack....

 class where exhibitors in Hunt seat

Hunt seat

Hunt seat is terminology used in the United States and Canada to refer to a style of forward seat riding commonly found at American horse shows. Along with Dressage, it is one of the two classic forms of English riding. The Hunt seat is based on the tradition of fox hunting...

 tack and attire perform on the flat at a walk, trot, canter and hand gallop, and then jump two low fences. The desired horse in this competition is to resemble a quiet, well-mannered working hunter

Show hunter

The show hunter is a type of show horse that is judged on its movement, manners, and way of going, particularly while jumping fences. The horses are shown in hunt seat style tack, and are often of Warmblood or Thoroughbred type, though a hunter-style pony is also seen in youth classes...

 rather than the more animated American-style show hack

Show hack

The show hack is a type of ridden show horse, exhibited to a standard first established in England.Affiliated showing and breeding of the show hacks in the United Kingdom is overseen by the British Show Horse Association....

.

Hunter hacks are scored on their manners, gait, and conformation, as well as their ability to jump with an even arc and stride over the center of the fences. Points are taken off for excessive speed or slowness, breaking gait

Horse gait

Horse gaits are the various ways in which a horse can move, either naturally or as a result of specialized training by humans.-Classification:...

 or failing to take a gait when called for, carrying the head too high or low, taking the wrong lead

Lead (leg)

Lead refers to which set of legs, left or right, leads or advances forward to a greater extent when a quadruped animal is cantering, galloping, or leaping. The feet on the leading side touch the ground forward of its partner. On the "left lead", the animal's left legs lead...

 at the canter

Canter

The canter is a controlled, three-beat gait performed by a horse. It is a natural gait possessed by all horses, faster than most horses' trot but slower than the gallop, and is used by all riders. The speed of the canter varies between 16-27 km/h , depending on the length of the stride of the horse...

, the rider being on the wrong diagonal at the trot

Trot (horse gait)

The trot is a two-beat diagonal gait of the horse, where the diagonal pairs of legs move forward at the same time. There is a moment of suspension between each beat....

, the horse nosing out or flexing behind the vertical, and stumbling.