Behavioral assessment of aggression towards humans in the domestic dog

Behavioral assessment tools are used by companion animal professionals and animal rescue organizations to evaluate the risk of various behavioral problems in dogs. This dissertation encompasses three studies designed to assess the validity of such tools as predictors of canine aggression towards humans. In the first study, an evaluation was made of a graded behavioral assessment tool used in a program for transporting dogs between shelters to enhance adoption rates. The tool was found to have test-retest reliability within, but not between, shelters. Dogs that failed the assessment were subsequently more likely to be euthanized due to human-directed aggression than dogs that passed the assessment. However, behavior in the assessment was not a reliable predictor of overall owner reports of aggression towards people following adoption. The second study involved an investigation of a different behavioral assessment tool to identify behaviors exhibited during the assessment that were reliable in predicting humandirected-aggression following adoption in dogs subsequently returned to the shelter. Findings indicated that aggression towards people was predicted by discrete behaviors displayed during the assessment, with snapping, whirling and stiffening being associated with future bites at strangers, and growling and shying/cowering being associated with threatening both strangers and familiar people. The third study investigated the effectiveness of the same behavioral assessment tool in discriminating between owned dogs with and without a history of aggression towards humans. The assessment was reliable for identifying dogs that had previously bitten humans, which exhibited more lunging and less looking away from the tester than dogs with no history of aggression. This research indicates that behavior assessment has some predictive power in the detection of human-directed aggression in dogs. However, it was found that human factors involved in behavioral assessment at shelters, and in the reporting of aggressive behavior by dog owners, influenced the validity of data used to determine outcomes for dogs relinquished to shelters. An improved understanding of dog non-verbal communication and human-related factors is needed to improve predictability in assessment, thereby reducing the risk of canine aggression towards humans