DRD2 is associated with fear in some dog breeds

Behavioral problems occur frequently in dogs and represent a significant threat to dog welfare. Anxiety, phobias, and fears comprise most of the canine behavioral conditions. The identification of an association between specific behavioral phenotypes and genetic variants of candidate genes would be a valuable tool in selection for dogs less susceptible to anxiety and fear, which may improve animal welfare. The DRD2 gene encodes the dopamine receptor 2. In this study, we found 8 SNPs in the DRD2 gene of the Havanese, a breed that shows large variation in a behavioral phenotype that manifests itself as a tendency to react fearfully by withdrawing in social situations. Significant associations were detected between 2 SNPs in exon 2 of the DRD2 gene and increased social fear in Havanese dogs (n = 158), as evaluated through observation by an external evaluator (respective allelic odds ratio: 4.35, 4.07) and through owner questionnaires (respective allelic odds ratio: 1.96, 2.2). Because different types of fear-related behavioral disorders commonly co-occur, the SNPs in exon 2 were also investigated for possible association to noise reactivity in 5 breeds: Havanese (n = 121), collie (n = 94), Irish soft-coated wheaten terrier (n = 44), Nova Scotia duck tolling retriever (n = 33), and standard poodle (n = 29). Significant associations were detected between SNPs in exon 2 of the DRD2 gene and noise reactivity in the Irish soft-coated wheaten terrier (respective allelic odds ratio: 2.64, 2.88) and collie (allelic odds ratio: 3.03). The same SNP alleles were associated with the beneficial phenotypes in the 3 breeds.