Does perceived trainability of dog (Canis lupus familiaris) breeds reflect differences in learning or differences in physical ability?

Researchers have reported perceived differences in trainability between different dog breeds. These reports could either be the result of underlying differences in learning or differences in physical capabilities. Four studies were conducted to investigate this issue. In Study 1 the level of agility metal-winners amongst those breeds perceived to be high and low in trainability did not deviate significantly from their respective levels of participation in the sport. In Study 2 the level of precision amongst those dogs perceived to be high and low in trainability did not deviate significantly in a real agility competition (P>0.05), but these dogs did differ in speed (P<0.05). In Study 3 the amount of training time necessary to achieve agility precision mastery did not significantly differ amongst dogs from breeds perceived to be high and low in trainability (P>0.05), but there was a significant difference in speed. Finally, in Study 4 breeds considered to be high in trainability were found to be relatively physically homogenous in respects to height, in comparison to breeds considered to be low in trainability. Overall, the results of these studies are more supportive of a physical capability interpretation of perceived breed differences in trainability, than a more cognitive interpretation.