A synopsis of Matsumoto, Y., Konno, A., Ishihara, G. et al. Genetic dissection of behavioral traits related to successful training of drug detection dogs. Sci Rep 13, 7326 (2023). https://doi.org/10.1038/s41598-023-33638-6

What genes make a great drug detection dog? That’s what Miho Inoue-Murayama and colleagues at the Wildlife Research Center at Kyoto University set out to understand. They conducted a genome-wide association study to see if they could find specific genetic markers and behavioral characteristics that correlate with successful training of drug detection dogs.

They worked with a total of 624 dogs, all either purebred German Shepards or pure-bred Labrador Retrievers, approximately 1 year old, with no prior scent work training. The training itself takes 4 months. Dogs were trained to find a range of controlled substances using positive reinforcement with social rewards. Canine trainers played tug-of-war with the dogs using a rolled towel with a target scent. The success or failure of dog training for scent work was determined by a double-blind detection test for each dog-handler pair, evaluated by an independent panel. Approximately half of the German Shepards and one-third of the Labrador Retrievers qualified.

To quantify the behavioral characteristics of the dogs, trainers were asked to score seven traits related to the success of detection training. Dogs were assessed early in the training, to get a sense of the innate temperament of the dog prior to extensive training. The traits were: activity (the amount of general activity typically observed), boldness (low fearfulness displayed toward unfamiliar environments), concentration (attention span during training), friendliness to humans (willingness to interact with humans), independence (self-confidence, willingness to work without relying on humans), interest in the target (degree of interest in a reinforcer), and tolerance to dogs (low aggressiveness towards other dogs).

In German Shepards, the qualified group significantly differed from the unqualified group in activity, boldness, concentration, and interest in the target. In Labrador Retrievers, all traits, except friendliness to humans, differed between the two groups. Sex of the dog was not significant.

The genomic analyses looked at almost 100,000 distinct genetic markers known as SNPs or single nucleotide polymorphisms. A SNP is a single base-pair change in a genetic sequence that is found in or near a potential gene of interest. Using these data, they found that three traits with high heritability: ‘qualification’ and ‘boldness’ in German Shepards, and ‘tolerance to dogs’ in Labrador Retrievers. In other words, the amount of variation in these traits was well explained by overall differences in the frequencies of the genetic markers.

They also found correlations with the trait values for ‘friendliness to humans’ in Labrador Retrievers and ‘interest in the target’ in German Shepards to specific genetic markers, suggesting 61 possible target genes associated with these traits. Out of these 61 genes, 12 have behavioral or neurological effects in mice and will be studied further. Two of these genes influence anxiety response and novelty seeking behavior.

Currently, only 30-50% of dogs trained in drug detection are successful. This study helps us to understand which dogs are more likely to succeed in that training, both in terms of their behavior and the genes that underlay that behavior.