Advancing Genetic Selection and Behavioral Genomics of Working Dogs Through Collaborative Science

Comparative neurogenetics of dog behavior complements efforts towards human neuropsychiatric genetics

Domestic dogs display a wide array of heritable behaviors that have intermediate genetic complexity thanks to a long history of human-influenced selection. Comparative genetics in dogs could address the scarcity of non-human neurogenetic systems relevant to human neuropsychiatric disorders, which are characterized by mental, emotional, and behavioral symptoms and involve vastly complex genetic and non-genetic risk factors. Our review describes the diverse behavioral "phenome" of domestic dogs, past and ongoing sources of behavioral selection, and the state of canine behavioral genetics. We highlight two naturally disordered behavioral domains that illustrate how dogs may prove useful as a comparative, forward neurogenetic system: canine age-related cognitive dysfunction, which can be examined more rapidly given the attenuated lifespan of dogs, and compulsive disorders, which may have genetic roots in purpose-bred behaviors. Growing community science initiatives aimed at the companion dog population will be well suited to investigating such complex behavioral phenotypes and offer a comparative resource that parallels human genomic initiatives in scale and dimensionality.

Identification of Genetic Risk Factors for Monogenic and Complex Canine Diseases

Advances in DNA sequencing and other technologies have greatly facilitated the identification of genetic risk factors for inherited diseases in dogs. We review recent technological developments based on selected examples from canine disease genetics. The identification of disease-causing variants in dogs with monogenic diseases may become a widely employed diagnostic approach in clinical veterinary medicine in the not-too-distant future. Diseases with complex modes of inheritance continue to pose challenges to researchers but have also become much more tangible than in the past. In addition to strategies for identifying genetic risk factors, we provide some thoughts on the interpretation of sequence variants that are largely inspired by developments in human clinical genetics.

Genome scanning of behavioral selection in a canine olfactory detection breeding cohort

Research on working dogs is growing rapidly due to increasing global demand. Here we report genome scanning of the risk of puppies being eliminated for behavioral reasons prior to entering the training phase of the US Transportation Security Administration's (TSA) canine olfactory detection breeding and training program through 2013. Elimination of dogs for behavioral rather than medical reasons was based on evaluations at three, six, nine and twelve months after birth. Throughout that period, the fostered dogs underwent standardized behavioral tests at TSA facilities, and, for a subset of tests, dogs were tested in four different environments. Using methods developed for family studies, we performed a case-control genome wide association study (GWAS) of elimination due to behavioral observation and testing results in a cohort of 528 Labrador Retrievers (2002-2013). We accounted for relatedness by including the pedigree as a covariate and maximized power by including individuals with phenotype, but not genotype, data (approximately half of this cohort). We determined genome wide significance based on Bonferroni adjustment of two quasi-likelihood score tests optimized for either small or nearly-fully penetrant effect sizes. Six loci were significant and five suggestive, with approximately equal numbers of loci for the two tests and frequencies of loci with single versus multiple mapped markers. Several loci implicate a single gene, including CHD2, NRG3 and PDE1A which have strong relevance to behavior in humans and other species. We briefly discuss how expanded studies of canine breeding programs could advance understanding of learning and performance in the mammalian life course. Although human interactions and other environmental conditions will remain critical, our findings suggest genomic breeding selection could help improve working dog populations.