Owner perceived differences between mixed-breed and purebred dogs

Studies about the behaviours of mixed-breed dogs are rare, although mixed-breeds represent the majority of the world's dog population. We have conducted two surveys to investigate the behavioural, demographic, and dog keeping differences between purebred and mixed-breed companion dogs. Questionnaire data were collected on a large sample of dogs living in Germany (N = 7,700 purebred dogs representing more than 200 breeds, and N = 7,691 mixedbreeds). We found that according to their owners, mixed-breeds were (1) less calm, (2) less sociable toward other dogs, and (3) showed more problematic behaviour than purebreds (p < 0.001 for all). Mixed-breeds and purebreds were similar in trainability and boldness scores. However, twelve out of 20 demographic and dog keeping factors differed between purebred and mixed-breed dogs, and two factors showed considerable (>10%) differences: neutering was more frequent among mixed-breeds, and they were acquired at older ages than purebreds (p < 0.001 for both), which could result in the observed behaviour differences. After controlling for the distribution of the demographic and dog keeping factors, we found that mixedbreeds were (1) more trainable than purebreds, (2) less calm, and (3) showed more problematic behaviour than purebreds (p < 0.001 for all). We discuss that these differences at least partly might be due to selective forces. Our results suggest that instead of being the "average" dogs, mixed-breeds represent a special group with characteristic behavioural traits.