Anxiety disorders include different forms of pathological fear and anxiety and rank among the most common health concerns in human medicine. Millions of people become affected every year, and many of them do not respond to treatments. Anxiety disorders are heritable, but genetically complex. As a result, traditional gene mapping methods in the human population with prominent locus and allelic heterogeneity have not succeeded. Similarly, rodents have provided some insights into the circuitry of anxiety, but naturally occurring versions do not exist and gene deletion studies have not provided adequate models. To break through and identify new anxiety genes, I propose a novel and unique approach that resorts to man s best friend, dog. Taking advantage of the exaggerated genetic homogeneity characteristic of purebred dogs, recent genomics tools and the existence of naturally occurring heritable behaviour disorders in dogs can remedy the current lack of a suitable animal model of human psychiatric disorders. I propose to collect and perform a genome-wide association study in four breed-specific anxiety traits in dogs representing the three major forms of human anxiety: compulsive pacing and tail-chasing, noise phobia, and shyness corresponding to human OCD, panic disorder and social phobia, respectively. Canine anxiety disorders respond to human medications and other phenomenological studies suggest a share biological mechanism in both species. The proposed research has the potential to discover new genetic risk factors, which eventually will shed light on the biological basis of common neuropsychiatric disorders in both dog and human, provide insight into etiological mechanisms, enable identification of individuals at high-risk for adverse health outcomes, and facilitate development of tailored treatments.