Behavioural susceptibility to environmental influences in obesity– evidence from a companion animal model

Obesity is often pejoratively viewed as the consequence of poor self-restraint with the influence of genetics on individuals’ drive to eat overlooked. We studied pet dogs (Canis familiaris) as a compelling animal model in which obesity develops spontaneously, subject to similar environmental influences as in their human counterparts and in which artificial selection means dogs within a breed are genetically homogeneous. In electronic health records from 1.1 million dogs, we showed wide variation in the probability of obesity in different breeds, evidence that obesity is highly heritable in this species. Using a validated questionnaire in ~ 15,000 dog/owner dyads we show that food motivation is a key driver of obesity in dogs, and that high food motivation renders affected dogs particularly susceptible to an obesogenic environment. As well as being of veterinary interest, this is of relevance to human obesity as compelling, data-driven evidence of how behavioural susceptibility to environmental risk governs obesity outcome.