Different strategies can be used in arder to assess animal welfare, depending on species that will be evaluated, indicators selected, the resources available and the husbandry conditions in which animals are kept. The aim of the present study was to assess welfare of Chilean Creo le Horses during differentsituations common to their husband1y system by the use of different welfare indicators, thought to be appropriate according to their age and management. The first manuscript corresponds to a literature review of undesired behaviours in horses, with a special focus on stereotypic behaviours, since their development is usually associated with horses being managed in suboptimal environments either currently or in the past, and have been proposed as indicators of poor welfare. The second and third manuscripts describe the frequency of presentation of stereotypic and other abnormal behaviours, and their possible association with sorne current husband1y practices and individual animal characteristics in two populations of horses, Chilean Creole Horses and chilean Thoroughbred racehorses. In the fourth manuscript the variation of normal behaviour as a result of weaning was described in Chilean Creo le foals; direct observation of the foals befo re and after weaning was used to assess their behavioural strategy adopted in order to cope with this husband1y practice known to cause distress. Finally in the fifth manuscript physiological indicators were used to assess the possible negative effect of the chilean rodeo on the welfare of these horses, two real situations were assessed, official rodeo competitions and training at their farms of origin.For the present study behavioural indicators associated with husband1y practices resulted to be more useful when assessing the welfare state of the Chilean Creole Horses than when using blood variables by their own. All studies conducted raised more questions about possible breed specific characteristicsor the chilean husbandry system used for these horses that seem to give them an advantage when confronted to aversive management practices.PFCHA-BecasDoctor en Ciencias Veterinarias180p.PFCHA-BecasTERMINADA