Researchers Find Link Between PSD Development, Straight Hocks

For every degree of increase in hock angle, researchers found a 12% greater chance of a horse having proximal suspensory desmopathy (PSD).

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To measure hock angle Dyson placed markers on horses’ legs, drew lines between the center of each marker, and calculated the angle electronically (this can also be done with a protractor, she noted). This hock angle is 166°. | Photo: Courtesy Dr. Sue Dyson

Proximal suspensory desmopathy (PSD) causes debilitating, possibly career-ending, hind-limb lameness, particularly in sport horses. But new study results could help owners and veterinarians prevent it—or at least select to avoid it. British researchers have learned that PSD development could be associated with straight hock conformation.

For every degree of increase in hock angle (leading to straighter hocks), the researchers found a 12% greater chance one of their study horses would have PSD, said Sue Dyson, MA, Vet MB, PhD, DEO, FRCVS, head of clinical orthopedics at the Animal Health Trust Centre for Equine Studies, in Newmarket, United Kingdom.

Horses with PSD have inflammation and tissue damage in the upper part of the suspensory ligament, a structure that connects to the top back of the cannon bone, divides into two branches that attach to the proximal sesamoid bones, and lies under the superficial and deep digital flexor tendons and the check ligament. Traditional treatment approaches have generally involved an extended, expensive period of confinement or inactivity, although results are often poor, and Dyson’s group usually recommends surgery

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

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