Appendix Horse Characteristics – A Great All Rounder

Let’s take a look at appendix horse characteristics, a cross of one of the most popular horse breeds in the United States, the American Quarter Horse. This breed is a cross between a Quarter Horse and a Thoroughbred, with the goal of producing a horse with the best qualities of both. The foal born of this cross is eligible for registration with the American Quarter Horse Association and the American Appendix Horse Association.

Physical Appendix Horse Characteristics

The average appendix horse stands between 15 to 17-hands tall. The upper height of this range is taller than the average Quarter Horse. The potential for a taller horse comes from the Thoroughbred side of the breeding.

These horses weigh between 900 and 1,200 pounds. The build of an appendix horse can vary depending on how much influence the Quarter Horse and Thoroughbred parents have. You will see any from a chunky, compact, stocky type resembling a full Quarter Horse, to taller, leaner, and more blood looking like a Thoroughbred, to everything in between.

Appendix Horse Temperament

The personalities and brain of the sire and dam greatly influence the temperament of the foal. However, certain temperament traits run through particular breeds. American Quarter Horses have a reputation for calm, sensible, and trainable 

The Thoroughbred is hot-blooded and usually has a more flighty, and fiery temperament. However, there are exceptions. This means that an appendix can inherit this, which gives them a less calm temperament than a Quarter Horse. 

Both breeds have a willingness to work, but novice riders are better off looking for a Quarter Horse over an appendix since they are more reliably calm. The appendix has a friendly personality, and generally enjoys interacting with people.

Appendix Horse Breed Colors

The American Quarter Horse Association accepts 17 coat colors in its registry, but limits white markings on the legs to the knee and below. The appendix does not come in the same range of colors, since the Thoroughbred does not carry as many in its genetic profile. The most common appendix horse colors are bay, grey, brown, and black. Less frequently, coat colors include palomino, buckskin, and chestnut. 

Appendix Horse Breed Colors

Appendix Health Conditions

Appendix horses have a higher risk of suffering from a number of health conditions. Hyperkalemic periodic paralysis (HYPP) is a disease that causes sporadic weakness or collapse and muscle tremors. It can also cause paralysis of the upper airway muscles, which during an attack causes the horse to make loud breathing sounds. 

A severe attack can cause sudden death from heart failure or respiratory paralysis. HYPP is, unfortunately, a disease that disproportionately affects Quarter Horses and is inheritable. It is passed to an appendix horse through its Quarter Horse parent.

Another disease affecting appendix horses is polysaccharide storage myopathy (PSSM). PSSM is a genetic mutation that causes the horse’s body to store too much glycogen in its muscles. This can make the horse sore and stiff.

This soreness and stiffness are called tying-up or exertional rhabdomyolysis. Horses suffering from an episode often don’t like moving much, sweat, and show lameness.

Malignant hyperthermia (MH) is another disease the appendix can inherit from its Quarter Horse parent. Though rare, MH, is life-threatening when it occurs. It is triggered in at-risk horses when they are exposed to anesthesia drugs. 

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With MH the horse’s body has an increased muscle metabolism caused by high levels of calcium released from skeletal muscle cells. During this process, body temperature increases and can lead to a hyper-metabolic state, which has a high fatality rate.

A horse carrying the MH mutation and the PSSM1 mutation has a higher risk of severe tying-up.

Appendix Horse Uses

Appendix horse characteristics mean that it is an athletic and versatile horse. This makes the horse suitable for a large variety of equestrian activities. They make excellent pleasure horses, barrel racers, low-level jumpers, and ranch horses.

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The appendix horse mixes all the right qualities for an all-rounder type of horse. The only thing to keep in mind is some inherit a more Thoroughbred-like temperament, so not all are suitable for novice riders.

It is a good option for a taller rider as they tend to have more height than a Quarter Horse. The appendix is generally a good keeper, unlike the Thoroughbred that can take a lot of feeding to keep condition.

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