Roy, R. C., Cockram, M. S., Dohoo, I. R. and Riley, C. B. 2015. Injuries in horses transported to slaughter in Canada. Can. J. Anim. Sci. 95: 523-531. Horses transported in groups on long journeys to slaughter are at risk of injury. Injuries can occur following trauma and aggression from other horses. This study quantified injuries in 3940 horses from 150 loads that arrived at a slaughter plant in Canada. Surface injuries were quantified using visual assessment. Digital thermography was used to detect areas of raised surface temperature. Carcasses were assessed for bruising. Multivariable regression analysis was used to examine the associations between journey characteristics and the risk of injury. There was a significant association between journey duration and the number of horses per load with surface injuries (P<0.001). In 100 horses from 40 loads studied in detail, 33% had surface injuries identified by visual assessment, 48% had areas of raised surface temperature identified by thermography and 72% had bruising identified by carcass assessment. The levels of agreement between identification of injury by thermography and that by identification of visible injuries and carcass bruising were low. Pre-transport assessments could not be performed and hence injuries could not be linked causally to the transport conditions alone. However, the detailed assessments of injury and the use of multivariable regression analysis showed that long journeys were associated with injuries.