A comparison between a direct and an indirect method for assessing aggressiveness in dogs

s 55 organized by Japan Kennel Club in 2008 and 2009. In this study we focused on the fear and the reactivity as candidate temperament factors and chose three dog breeds, Shiba Inu, Labrador retriever and Chihuahua, because they have different tendencies in showing aggressive behaviors (Takeuchi and Mori, 2006). Questionnaires contained questions about general information, 14 items about their dogs’ responses to humans, sounds and small animals, and 6 items about aggression toward owners, children, strangers and dogs. Owners were asked to score their dogs’ response with 5-point frequency scales (1 5 never, 2 5 occasionally, 3 5 sometimes, 4 5 often and 5 5 always). In total, owners of 91 Shiba dogs, of 109 Labrador retrievers and of 100 Chihuahuas volunteered to fill out the questionnaire. At first, factor analysis was conducted using 14 items in each breed, and then factor scores calculated as the average of the questionnaire items comprising each factor was compared between the calm dogs (showing never or occasionally aggressive behavior: scale % 2) and the aggressive dogs (showing aggressive behavior more frequently: scale R 3) in the Shiba breed. The factor analysis resulted in extraction of three factors, i.e., ‘‘reactivity to small animals (F1)’’, ‘‘fear of human (F2: negatively loaded)’’ and ‘‘reactivity to sound and movement (F3)’’, consistently from all the three breeds. The fourth factor, ‘‘fear of sounds (F4)’’ was extracted only from Labrador Retrievers and Chihuahuas. In addition, F1, F2 and F3 are composed of the same items among the three breeds, whereas F4 has the same composition between the two breeds. The Shiba dogs showing owner-directed aggression had significantly higher F3 scores, while those with child-directed and stranger-directed aggressions had lower F2 scores and higher F3 scores as compared with calm individuals, respectively. No such difference was found regarding the dog-directed aggression. These results suggest that the temperament factors such as fear and reactivity may differently contribute to the owner-directed aggression from the stranger (or child)directed aggression in Shiba Inu breed.