A U.K. researcher examined how age, exercise, and riding discipline and level affect hock joints, and she hopes to make recommendations on how to take better care of equine athletes' hocks.

Orthopedic research technician Marion Branch, MV, of the Animal Health Trust in Newmarket, England, used magnetic resonance imagining (MRI) to examine 130 horses' hocks in a study published in the Equine Veterinary Journal.

The scanned joints were then processed in pathology to examine the histology (cell makeup) of micron-thick slices of bone and cartilage and to measure the depth of particular pathologies of the joint. The data were then correlated with measurements from various MRI views. Branch looked for predictable patterns of degenerative joint disease in the cartilage and subchondral bone of these groups. Using the horse's history (age, breed, discipline), she was able to analyze the information.

Branch found that in older horses, loading is mostly on the outside edges, where thicker subchondral bone (bone beneath the joint cartilage) is found. "The intensity of the exercise is very important," she said. "The horse's joints undergo high load intensity with respect to some areas of the joint being subjected to higher loads than others during locomotion. We have seen a repeatable pattern of subchondral bone thickness across the distal tarsal joints of horses with no history of hind limb lameness that have been exercised at a low level, and we believe this is reflective of the pattern of loading across the joints.

"We've seen that osteoarthritis involves a lot of different types of lesions and structures in the joint," she continued. "There are obvious differences between subchondral bone patterns of different exercise groups." Subchondral bone thickness increases with age, and hind limb cartilage starts out "squishy" and hardens with age, resulting in stiffness in older horses.

Harder cartilage doesn't absorb load impact as well, which could lead to more pressure on bones and resulting pathology. Branch's studies will help her and other researchers understand which equine athletes are prone to develop painful osteoarthritis and where, and suggest preventive strategies to help avoid these problems.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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