The impulsive horse: Comparing genetic, physiological and behavioral indicators to those of human addiction.

•Genotype (DRD4) did not have a significant effect on any of the parameters measured.•Spontaneous blink rate but not behavioural initiation rate correlated significantly with levels of impulsivity.•There was no clear association of heart rate variability parameters with either measures of central dopaminergic activity or impulsivity/compulsivity.•Some aspects of the data suggest that the horse may be a useful animal model for assessing the genetic and environmental factors that lead to the physiological and behavioral phenotype of human addiction.