Results: Metacarpal/MT condylar IRU was identified in 103/220 horses with only 3/220 having parasagittal IRU. Moderate/marked IRU was identified in the forelimb MC and hindlimb MT condylar regions in 62 and 48 horses respectively with palmaromedial and plantarolateral IRU most common. Forelimb cases had fewer starts (P<0.001), reduced earnings (P<0.001), fewer wins (P=0.03) and fewer overall places (P<0.001) than controls. Hindlimb cases had fewer starts (P=0.003) and reduced earnings (P=0.01) than controls. Cases were more likely to return to racing later than controls following a rest period (P=0.003). Cases were older than scintigraphy controls (P<0.001). No significant differences idenitified in HR-pQCT variables of distal MC and midshaft between cases and controls. Epiphyseal BV/TV was greater in injured limbs of horses with any fatal limb injury compared to controls (OR 1.20, 95% CI 1.01-1.42, P=0.034). An eiphyseal BV/TV >0.74 resulted in a sensitivity of 82.8% and specificity of 62.5% in identifying horses with fatal limb injury. In horses without condylar fracture, increased subchondral bone thickness was associated with POD lesions in the adjacent condyle (rs=0.65, P<0.001). Conclusions: In TB racehorses presenting for lameness or poor performance MC/MT condylar IRU is the most common abnormality identified within the fetlock joint and condylar fractures are rarely identified using scintigraphy. Racehorses with moderate/marked condylar IRU have a shortened racing career, are less successful than age/sex matched controls and are older than other racehorses presented for scintigraphy. Increased BV/TV of the distal metacarpus may be useful for determining horses at risk of any fatal breakdown injury but appears to be less useful for predicting condylar fracture and HR-pQCT of the third metacarpal bone midshaft appears to be of no value for predicting fatal injury.
|Qualification||Master of Applied Science|
|Place of Publication||Australia|
|Publication status||Published - 2013|