The Horse

APR 2019

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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42 April 2019 The Horse | Another important population this team has studied is racehorses rehabili- tating from injury. Their goal is to identify inflammatory markers to help trainers determine the rate at which they can safely bring horses back into training and how much training a horse can tolerate. Identifying Fatality Risk Factors Some racing and training injuries are so catastrophic that they result in death or euthanasia. In a retrospective study led by Peter Physick-Sheard, BVSc, Dipl. Vet- Surg, MSc, FRCVS, at the University of Guelph 1 , in Ontario, researchers analyzed racehorse deaths logged with the Ontario Racehorse Death Registry from 2003 to 2015 that occurred within 60 days of a race or trial entry (timed workouts and Standardbred qualifying races). The researchers examined differences between racing Thoroughbreds, Standard- breds, and Quarter Horses as they related to age, sex, and circumstances of death, such as time and location, suggested cause, and whether it was an exercise- associated mortality (EAM) or non- exercise-associated mortality (NEAM). The mean combined EAM and NEAM mortality rate was highest for Thor- oughbreds (2.93 deaths per 1,000 starts), which was 4.6 times higher than that of Standardbreds (0.63/1,000 starts). Quarter Horses landed in the middle (2.08/1,000 starts). Thoroughbred mean annual EAM was 8.1 times that of Standardbreds. Physick-Sheard's team said their most notable finding was that Thoroughbred mortality was highest in young, intact male horses. In Thoroughbreds and Quarter Horses, mortality rates of all sexes were higher at age 2 than any other. Researchers noted a higher mortality rate across all breeds for younger horses (possibly due to skeletal immaturity and a propensity toward fatigue) and older horses (possibly due to cumulative dam- age). The mortality risk among middle- aged horses was lower. Basically, says Physick-Sheard, mortality rate followed a curve, falling over the first two to three years, then increasing. Groups were aged by year, for Thoroughbreds, from 2 to 10. When looking at cause of death, "mus- culoskeletal injury, including breakdowns, fractures, dislocations, and tendon ruptures, was the largest category," said the authors. Thoroughbreds experienced musculoskeletal injuries 8.59 times more than Standardbreds. The second-most-common cause was collapsing for no reason and sudden death. Colic; medical problems (e.g., SPORTS MEDICINE The fetlock is the most common site of muscu- loskeletal injury in racehorses. COURTESY DR. DOUG HERTHEL Ask your vet about BoneWise TM Did you know bone density and strength decline during layup and confinement? Available only through your veterinarian. Developed by:, 859-873-2974 A unique source of calcium and minerals that maintain bone density and strength when you need it most. TH 2019-04b

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