Approximately 8% of European performance horses engage in cribbiting behaviour (McGreevy et al.,1995, Redbo et al., 1998), a trait which can reduce both financial value and welfare status of the animal. An increase in prevalence to 26% was reported in those families originating from crib-biting sires (Vecchiotti and Galantini 1986), tentatively implying that a genetic component may be involved. Indeed, in a herd of Przewalski's horse, there was an 84% chance of offspring crib-biting if they originated from cribbing parents (Marsden and Henderson 1994). Finally, hereditary transmission has been more reliably demonstrated in the rodent, where stereotypy can be induced following 9 days of food restriction in the highly inbred DBA mouse strain, but not the C57 strain (Cabib and Bonaventura 1997) suggesting 1) propagation of a genetic component within the DBA genotype and 2) the requirement of an environmental stressor for stereotypy development. In the rodent model this genetic pre-disposition manifests physiologically as a facilitation of dopamine transmission within the mesolimbic projection following a period of stress (Cabib et al., 1998).