Quarter Horse

The modern breed combines that Colonial stock with Thoroughbred blood, including the imported stallion Janus, foaled in 1746 and standing in Virginia from 1756, and, critically, with the cow-working horses of the Southwest.

The American Quarter Horse Association was founded in 1940, and the first horse in the book was the stallion Wimpy, registered as P-1 in 1941. By 2014 the registry counted nearly three million horses worldwide, and Texas and Oklahoma have both made the breed their state horse.

They are compact and heavily muscled through the hindquarters, standing 14 to 16 hands, with halter-bred individuals to 17. Sorrel is the most common of a long list of accepted colors.

The breed splits into two visible types: the stock type, short, stocky and agile, built for cattle, and the taller, leaner racing and hunter type that shows its Thoroughbred blood.

Over a quarter mile they have been clocked at 44 miles an hour, which is the fact the name records.

They are calm and trainable, which is why they dominate as a general riding horse.

Cow sense is a temperament trait as much as a physical one: an inherited instinct for reading and controlling cattle that makes them the ranch and rodeo horse.

The cattle disciplines are the core: reining, cutting, barrel racing, roping, ranch work and rodeo.

Off the ranch they race a quarter of a mile, as they always have, and serve as the default general riding horse across North America.

A feed and exercise plan that follows the test results. A horse with HYPP needs its potassium kept down: University of Minnesota Extension lists alfalfa, molasses, soybean meal or oil and canola oil as high-potassium feeds, says pasture grazing is fine because its water content keeps intake low, and recommends regular exercise or turnout.

A horse with PSSM1, which AQHA puts at about 11 percent of the breed, needs daily exercise and a diet low in sugar and starch. UC Davis's Center for Equine Health says a low-starch, low-sugar grass hay and a good ration balancer is usually enough, and that 90 percent of affected horses kept on diet and exercise management have few or no episodes of tying up.

Tell your vet about the panel before any anesthetic. Malignant hyperthermia can be triggered by some anesthetic drugs, and general anesthesia can bring on an HYPP episode.

The trade is genetic disease. The breed carries five well-documented heritable conditions including HYPP, HERDA and PSSM1. All are testable, panel testing is available, and any purchase should include the results.

The numbers behind that advice: HYPP is dominant and traces to the stallion Impressive. AQHA requires testing for any horse with Impressive bloodlines and, since 2007, has not registered horses carrying two copies. About 3.5 percent of the population carries HERDA, around 11 percent PSSM1, and around 10 percent GBED; malignant hyperthermia and lethal white syndrome are also testable. Ask for the panel results, not a verbal assurance.

Registration runs through the American Quarter Horse Association; confirm the number before you bid.

Recent sale prices on HoofnHorn, where there are any, are further down this page.