EQUINE VETERINARY EDUCATION / AE / MAY 2015
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a)
b)
Fig 2: Fractures of the dorsal aspect of the third to seventh spinous processes, radiographs taken (a) the day after the horse fell from height directly onto its withers and (b) 6 weeks later (Case 8).
0 1 2 3 4 5 6 7 8
History of fall Stiff action
Fig 3: Clinical features of horses with fractured withers from the Hong Kong Jockey Club between 2003 and 2013 (n = 8).
8 7 6 5 4 3 2 1 0
T2 T3 T4 T5 T6 T7 Dorsal Spinous Process affected
Fig 4: Frequency of fracture in particular vertebrae in cases of fractured withers at the Hong Kong Jockey Club between 2003 and 2013 (n = 8).
rest for 4 weeks followed by a graduated return to exercise, with initial walking in-hand progressing to the walking machine. Ridden work was discouraged until at least 8 weeks post injury.
Return to racing The return to exercise after injury is described in Table 1. All horses returned to walking in-hand within one month of injury. Five of the 7 cases had started ridden work (walk, trot and canter) prior to 8 weeks after injury, with 3 horses having galloped by the time this period had elapsed. Two horses presented with pain and instability of the DSP on palpation on initiation of ridden work, with radiographs showing a lack of callus formation (Fig 2). In these 2 horses, work under saddle
T8 T9
Swelling around withers
Pain on wither
palpation Clinical features
was delayed until resolution of the clinical signs, 85 and 132 days after injury, respectively.
Racing performance Horses undertook barrier trials (galloping under race conditions but at shortened distances and slower speeds) a median of 130.5 days after the initial injury occurred (Table 1). Post fracture, horses started in races a median of 13 (IQR 6–30.5) times and were placed a median of 3.5 (IQR 1.5–12.5) times. No horses were retired or subjected to euthanasia for
reasons directly related to wither fracture. Osteoarthritis of the metacarpophalangeal joints meant one horse was retired prior to returning to racing after injury and one horse was retired after 2 starts (with no placings). One horse was retired for persistently poor performance, defined by a failure to reach the required rating for racing in Hong Kong and one horse died from complications whilst undergoing a prosthetic laryngoplasty. The median rating at retirement was 57 (IQR 50–64).
Horses with the best racing performance after injury, based
on time to first race, time from first race to first win and retirement race rating (n = 4) returned to ridden work in <60 days after injury and returned to full training, which included galloping, by Day 74.
Discussion
The principal findings from this study are that fracture of the DSP of the withers carries an excellent outlook for return to successful racing in Thoroughbreds. Additionally, the convalescence period does not need to be as protracted as previously reported (Molnar et al. 2012; Piat et al. 2012). The condition was rare in the population, with a prevalence of 0.152%, which is lower than the range of 0.32–1.81% previously
© 2015 EVJ Ltd Crepitus Spinal
deviation/ flattening/ malformation
Number of horses
Number of horses
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