The aim of this study was to determine whether objective measures of laterality could be used to identify dogs with a high probability of successfully completing a Guide DogTraining Programme. Three categories of laterality (motor, sensory, and structural), were assessed in 114 dogs entering guide dog training. Significant predictors of success were identified: the direction of laterality (P = 0.028), paw preference category in the ‘Kong’ test (P = 0.043), hindpaw clearance height (P = 0.002), laterality indices for a number of measures in the Sensory Jump test, and chest hair whorl direction (P = 0.050). This is the first study to report a structural marker of canine behaviour. All three categories of laterality may be used to predict the ...