Oxytocin Receptor Gene Polymorphisms Are Associated with Human Directed Social Behavior in Dogs (Canis familiaris)

Abstract

The oxytocin system has a crucial role in human sociality; several results prove that polymorphisms of the oxytocin receptor gene are related to complex social behaviors in humans. Dogs' parallel evolution with humans and their adaptation to the human environment has made them a useful species to model human social interactions. Previous research indicates that dogs are eligible models for behavioral genetic research, as well. Based on these previous findings, our research investigated associations between human directed social behaviors and two newly described (−212AG, 19131AG) and one known (rs8679684) single nucleotide polymorphisms (SNPs) in the regulatory regions (5′ and 3′ UTR) of the oxytocin receptor gene in German Shepherd (N = 104) and Border Collie (N = 103) dogs. Dogs' behavior traits have been estimated in a newly developed test series consisting of five episodes: Greeting by a stranger, Separation from the owner, Problem solving, Threatening approach, Hiding of the owner. Buccal samples were collected and DNA was isolated using standard protocols. SNPs in the 3′ and 5′ UTR regions were analyzed by polymerase chain reaction based techniques followed by subsequent electrophoresis analysis. The gene–behavior association analysis suggests that oxytocin receptor gene polymorphisms have an impact in both breeds on (i) proximity seeking towards an unfamiliar person, as well as their owner, and on (ii) how friendly dogs behave towards strangers, although the mediating molecular regulatory mechanisms are yet unknown. Based on these results, we conclude that similarly to humans, the social behavior of dogs towards humans is influenced by the oxytocin system.

Differential effects of oxytocin on social sensitivity in two distinct breeds of dogs ( Canis familiaris )

“…The potential role of epigenetic factors contributing to breed differences is also raised by Passalacqua et al (2011) who found that hunting and herding breeds (to which Border Collies belong) looked at a person more than dogs from Mastiff-like and ancient breeds (to which Siberian Huskies belong) at the age of 4 month and when adults, but breed group differences were not seen in 2-month-old puppies. Therefore it is reasonable to assume that markedly different dog breeds (such as Border Collies and Siberian Huskies) Our results (together with the findings of Kis et al, 2014a) suggest that we should be cautious in concluding that oxytocin uniformly facilitate social behaviors in dogs. Similar claims have been made in the human literature (Bartz et al, 2011), however many researchers still report their findings as generalizable to a wider population.…”

“…In line with these findings, recent research has shown that behavioral responses to intranasal oxytocin treatment can be linked to oxytocin receptor (OXTR) genotype in humans (Feng et al, 2015;Marsh et al, 2012). OXTR polymorphisms, in turn, differentially influence social behavior of both different human populations (Chen et al, 2011) and dog breeds (Kis et al, 2014a). The present study investigates how social behavior is influenced by intranasal oxytocin treatment in two markedly distinct dog breeds (selected for different purposes).…”

“…We have some information about the polymorphic variations in the OXTR gene (Bence et al, 2013;Kis et al, 2014a), but the potential differences in baseline oxytocin levels across breeds -that might contribute to their differential reaction to oxytocin treatment -have not yet been investigated. The potential role of epigenetic factors contributing to breed differences is also raised by Passalacqua et al (2011) who found that hunting and herding breeds (to which Border Collies belong) looked at a person more than dogs from Mastiff-like and ancient breeds (to which Siberian Huskies belong) at the age of 4 month and when adults, but breed group differences were not seen in 2-month-old puppies.…”

“…The oxytocin or placebo administration was followed by a 40-minutelong waiting period (following the protocol by Kis et al, 2014b) that is presumed to be necessary for the central neuropeptide levels to reach plateau (Born et al, 2002). During this waiting period, dogs spent the first 25 minutes with an on-leash walk at the University Campus (avoiding any contact with other dogs or humans) during which the experimenter ensured that the owner did not make any social contact with the dog either (e.g.…”

“…Other studies have shown that polymorphisms in the regulatory region of the oxytocin receptor gene are related to human-directed social behaviors in dogs (Kis et al, 2014a) and that intranasal oxytocin administration influences dog's behavior in a wide range of contexts Romero et al, 2014).…”