A light gray appendix horse standing behind a white fence in the snow.


In This Article

  • History and Origins

  • Size

  • Breeding and Uses

  • Colors and Markings

  • Characteristics

  • Diet and Nutrition

  • Health and Behavior

  • Grooming

  • American Appendix Horse for You

  • How to Adopt or Buy

  • More Horse Breeds

The American Appendix Horse is a cross between an American Quarter Horse and a Thoroughbred. They are also often referred to as Appendix Quarter Horses. They are generally friendly horses, but their unpredictability means they are most suitable for experienced owners.

Their appearance varies, with some individuals having a stocky build, while others a slender and athletic one. Their build determines how they are used—whether that be in racing, work, or recreation.

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Breed Overview

Weight: 900 to 1200 pounds

Height: 15 to 17 hands (60 to 68 inches)

Body Type: Compact and muscular with smooth muscle mass and clean lines

Best For: Racing, jumping, work, recreation

Life Expectancy: 25 to 35 years

Appendix Horse History and Origins

The Appendix Quarter Horse is a first-generation cross between a thoroughbred and an American Quarter Horse. It gained popularity as breeders recognized that the cross retained the energy and temperament of the thoroughbred and the incredible speed and agility of the American Quarter Horse.

The American Quarter Racing and the National Quarter Horse Breeders associations merged in Texas in 1949, marking the beginning of the appendix registry. 

Appendix Horse Size

Weighing between 900 and 1200 pounds and measuring 15 to 17 hands high, or 60 to 68 inches, the Appendix Quarter Horse is built for athletics. 

An individual’s build differs depending on how much American Quarter Horse they have in them and how much Thoroughbred. Those with more Thoroughbred in them have a taller, more lean build. The opposite is true for individuals who have relatively more American Quarter Horse in their genes as they have a more muscular, stocky appearance.

Breeding and Uses

The American Appendix Horse was originally bred for racing. Because the breed is a cross between a Thoroughbred and an American Quarter Horse, it retains qualities from each. The strength of the Thoroughbred and the agility of the American Quarter Horse is a combination that can’t be beaten.

Considering their competence at racing, it’s natural that this breed is a sought-after racehorse. But the Appendix Quarter Horse has other skills, too, and is useful in multiple areas. They’re great for general riding and recreation as well as shows and competitions. The Appendix Quarter Horse is a well-rounded horse breed.

Colors and Markings

Appendix Quarter Horses come in every color, most commonly black, gray, and brown. More rare coat colors include bay, chestnut, and palomino.

Typically, their coat color does not affect whether or not they can be considered a full Appendix Quarter Horse. The only thing that matters for that classification is their bloodline.

A brown Appendix Quarter Horse standing in snowy field.

A brown Appendix Quarter Horse standing in snowy field.

Kostyantyn_Skuridin / Getty Images

Unique Characteristics of the American Appendix Horse

Because their genetics vary greatly, there is no specified body type of the Appendix Quarter Horse. Their height and muscularity really lies on a spectrum. And where an individual horse lies on that spectrum depends on how much Thoroughbred and how much Quarter Horse they have in them.

With that said, American Appendix Horses can be very tall. While the standard individual is between 15 and 17 hands tall, some are even taller. A stallion named The Game Changer is reported to be 18 hands tall, which is equivalent to six feet.

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Diet and Nutrition

Appendix Quarter Horses should be fed fresh grass, hay, and grains including rolled oats, bran, and barley. For healthy treats, give them carrots or apples.

Talk to your veterinarian about your horse’s nutrition. If their performance in sports or shows is of the utmost importance, you may need to add supplements and concentrates to their diet. 

Common Health and Behavior Problems

In terms of behavior, Appendix Quarter Horses are normally friendly and easy to train. Some individuals, however, can be too eager and excited, which causes them to be boisterous and a little stubborn. These individuals often need patience and trust in order to train.

Like Thoroughbreds, the rate of injury in Appendix Quarter Horses is relatively high due to the fact that they are often pushed to extremes while racing. Racing Appendix Quarter Horses can experience crippling or life-ending injuries, like breaks and sprains.

Appendix Quarter Horses are also prone to some genetic health issues, including:

  • Hyperkalemic periodic paralysis – Muscle twitching, muscle weakness, or paralysis
  • Polysaccharide storage myopathy – Damaged muscle tissue that can cause stiffness and pain
  • Malignant hyperthermia – A condition that makes a horse susceptible to a state of abnormally high metabolic activity. This can result in a high temperature, increased heart rate, rapid breathing, and more

Grooming

For a happy and healthy Appendix Quarter Horse, groom them daily. Like virtually all horses, they require regular brushing and occasional bathing. Their skin is relatively thin compared to other breeds, so be gentle.

Use a soft, bristled brush to brush its legs, face, girth, and saddle areas before taking them on a ride. Not only does this keep their coat clean and silky smooth, but it also distributes oil and sweat throughout their body. That’s especially important in the summer.

Pros

  • Athletic

  • Strong work ethic

  • Multipurpose

  • Fast

Cons

  • Can be overeager

  • Susceptible to health issues

  • Injury is common

  • Require experienced owners

Is the American Appendix Horse Right for You?

The friendliness of an Appendix Quarter Horse varies from horse to horse. Those with more American Quarter Horse blood in them tend to be gentle, easy to train, and friendly. On the other hand, horses with more Thoroughbred genes can be stubborn and standoffish to beginners. To play it safe, only those experienced should adopt or purchase an Appendix Quarter Horse. Experienced riders will be able to channel this breed’s intensity and will be rewarded with a uniquely smooth and thrilling ride.

How to Adopt or Buy American Appendix Horses

Contact the American Quarter Horse Association to find a reputable American Appendix Horse breeder. They will be able to help you find one with both purebred Thoroughbreds and American Quarter Horses and can provide clean bills of health.

Expect to pay an average of $3,000 for a healthy Appendix Quarter Horse. Ones listed at a lower price may be unhealthy. Bring a veterinarian to check it out before purchasing.

More Horse Breeds

The Appendix Quarter Horse is a unique breed that excels in a variety of areas. If you loved learning about them, explore our other similar breed profiles below:

  • American Quarter Horse
  • Thoroughbred
  • Paint Horse

Otherwise, you can dive into all of our other horse breed profiles.

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