English
The Appendix horse is a mixed breed produced by crossing an American Quarter Horse with a Thoroughbred. The cross is also known as an Appendix Quarter Horse.
Appendix horses can become eligible for permanent registration with the American Quarter Horse Association (AQHA) if they meet specific requirements. Some famous Quarter Horse sires were originally Appendix horses with Thoroughbred ancestry.
The Appendix combines the athleticism and stamina of the Thoroughbred with the agility and power of the Quarter Horse. This versatility makes them suitable for various equestrian disciplines including racing, jumping, and western events.
This profile will discuss the history, breed characteristics, health problems, and nutritional needs of the Appendix Quarter Horse. Keep reading to learn more about feeding and caring for Appendix horses.
Appendix Horse History
Thoroughbreds and American Quarter Horses are two of the most influential horse breeds, each with distinct characteristics that have been honed through centuries of selective breeding.
Introducing Thoroughbred bloodlines to the Quarter Horse gene pool was a strategic move aimed at enhancing the breed’s capabilities and broadening its appeal across various equestrian disciplines.
The AQHA initially established the Appendix registry to identify Quarter Horse crosses that did not have full AQHA registration. Today, the AQHA only recognizes crosses with particular breeds as Appendix Quarter Horses.
Origin
The American Quarter Horse is the most popular horse breed in North America. These horses trace their origins to early horses brought to the Colonies by English settlers, which were crossed with ponies bred by the indigenous Chickasaw and Cherokee people. [1]
Imported Thoroughbreds significantly influenced the development of the American Quarter Horse. One of the founding stallions of the breed, Janus, was an English Thoroughbred descended from the Godolphin Arabian. [1]
The Appendix registry was formed in 1949 after two Quarter Horse associations merged to form the AQHA. Initially designed to identify horses previously registered with the other groups until they passed inspection, the registry also included Quarter Horse-Thoroughbred crosses.
When concerns arose over the Appendix registry’s impact on the breed’s integrity, the AQHA refined requirements for registered Appendix horses. However, the term Appendix is often used to refer to any horse with mixed Thoroughbred and Quarter Horse blood.
Historic Use
Colonial settlers used the ancestors of Quarter Horses for short sprint races of a quarter-mile distance. Thoroughbred blood helped improve the stamina of these powerful sprinters.
When longer-distance Thoroughbred racing came into fashion on the Atlantic coast, the hardier Quarter Horses moved west. On the other side of the Mississippi, these horses crossed with Mustangs to produce a versatile mount ideal for working cattle on the range.
Crosses with Thoroughbreds continued even after the first official Quarter Horse breed organizations formed. A Thoroughbred stallion named Three Bars was one of the most influential sires of the Quarter Horse breed in the 20th century. [2]
DNA studies in Quarter Horses confirm significant genetic contributions from the Thoroughbred. One study found racing Quarter Horses had the closest relationships to Thoroughbreds. [1]
While Thoroughbred crosses are relegated to the Appendix registry, Appendix Horses that pass inspection are eligible for permanent registration with the AQHA. Some Appendix stallions, such as Impressive, become influential sires after gaining their registration.
Breed Registry
The American Quarter Horse Association still operates an Appendix registry in addition to the main registry. AQHA combined tentative and permanent registries in 1959 by automatically registering all foals born after 1962 to two fully registered parents.
Foals of registered Quarter Horses crossed with approved Thoroughbreds received numbers with the new Appendix registry. Crosses between registered Appendix Quarter Horses and fully registered Quarter Horses are also considered Appendix Quarter Horses. These horses could gain full registration as adults if they passed inspection or attained a register of merit.
The Thoroughbred parent must have breeding approval from the AQHA. Appendix horses are only eligible for breeding with fully registered Quarter horses. Foals with two Appendix parents or one Appendix Parent and one Thoroughbred parent are ineligible for the Appendix registry.
Breed Characteristics
The AQHA approves Thoroughbreds for crossbreeding based on their potential to improve the Quarter Horse’s breed standard. Appendix Quarter Horses are judged against this standard to earn permanent registration, but many Appendix horses inherit traits from both breeds.
Conformation
Most Appendix horses stand between 15 and 17 hands tall at the withers. These horses are often taller than purebred Quarter Horses due to their Thoroughbred ancestry.
Their overall appearance can vary between stock and racing horse types depending on the percentage of Thoroughbred and Quarter Horse bloodlines.
Many Appendix horses have a significant amount of Thoroughbred blood, resulting in a leaner, taller, and more long-legged build. More influence from stockier Quarter horse bloodlines produces a more compact horse with greater muscle mass.
The AQHA evaluates Appendix horses for registration based on the same characteristics preferred in purebred Quarter Horses. These breed characteristics include:
- Attractive head
- Refined throat latch
- Well-proportioned neck
- Sloping shoulder
- Short back
- Deep heart Girth
- Strong Loin
- Long hip
- Straight, correct legs
- Uniform muscling
Colours
Appendix Quarter Horses have the same coat colours as purebred Quarter Horses. Standard coat colours recognized by the AQHA include:
- Chestnut
- Sorrel
- Black
- Brown
- Gray
- Bay
Roan patterns and diluted colours are also found in the breed, including palomino, buckskin, cremello, grullo, bay roan, blue roan, and red roan.
The AQHA traditionally excluded horses with excessive white from registration but rescinded this rule in 2004. Overo is the only pinto pattern found in American Quarter Horses.
Temperament
There generally aren’t significant personality differences between Appendix horses and Quarter Horses. However, Appendix horses with more Thoroughbred blood tend to have hotter and more sensitive temperaments.
The ideal Appendix horse combines the steady mind and work ethic of the Quarter Horse with the intelligence and athleticism of the Thoroughbred.
Disciplines
Appendix horses are versatile pleasure mounts that can excel in many different disciplines. The steady Quarter Horse influence also makes these horses suitable for riders with a wide range of abilities.
Most share similar talents to Quarter Horses and commonly compete alongside them in AQHA events. Popular discipline classes for Appendix horses in AQHA events include:
- Reining
- Western Pleasure
- Cutting
- Trail
- Western riding
Appendix horses also inherit a talent for English disciplines from their Thoroughbred ancestry. These horses often excel in hunter under saddle and working hunter classes.
However, Thoroughbred blood has the most significant influence on racing Quarter Horses. Many of the horses competing in quarter-mile races today are Appendix horses.
Health Profile
Appendix Quarter Horses can inherit mutations associated with several genetic diseases commonly found in Quarter Horses. However, these horses are also susceptible to health problems that affect Thoroughbreds more frequently than Quarter Horses.
Genetic Diseases
Some veterinarians recommended screening Quarter Horses and related breeds with a 5-panel plus test for GBED, HERDA, HYPP, MYHM, MH, and PSSM1.
Glycogen Branching Enzyme Deficiency
GBED is an inherited fatal disease characterized by an inability to store glycogen correctly. The brain, heart, and skeletal muscles are unable to function normally. Most affected foals are stillborn or aborted. Foals that survive until birth typically die by 18 weeks. [3]
Studies estimate approximately 10% of Quarter Horses in the United States carry the mutation associated with the disease. It is most commonly found in Western pleasure and cutting horse bloodlines. [3]