Factors associated with the prevalence of stereotypic behaviour amongst thoroughbred horses passing through auctioneer sales

The objective of this study was to evaluate whether sex, age and/or coat colour were associated with the occurrence of stereotypic behaviour in the horse and to assess whether the occurrence of one type of stereotypy in an individual was associated with the occurrence of another specific type of stereotypy. The incidence of stereotypic boxwalking, weaving (both locomotor stereotypies) and oral stereotypy in 4061 Thoroughbred horses passing through five bloodstock auctions were recorded from sale declarations and information on returns. An overall prevalence of 5.1% was recorded, and varied with sex (P<0.001) and age (P<0.001) but not coat colour (P=0.495). Prevalence was higher in females, geldings, and 2-year-olds. Examination of the assumption that stereotypies are acquired independently suggested a higher than expected prevalence of animals with more than one stereotypy. The interaction was not the same for all forms of stereotypy recorded. The effect was greatest between boxwalking and weaving, (odds ratio 13.6) whilst combinations involving oral and locomotor stereotypies had lower odds ratios (between 2.9 and 4.9).