This literature review was aimed at analyzing whether stallion husbandry in groups is possible and desirable or poses risks. This was determined on the basis of different studies in order to be able to give practical recommendations from the viewpoint of animal welfare. Consequently, 50 different sources were analyzed, as well as observations of an experiment of the Swiss National Stud on the subject of change from single-stallion to group husbandry and its influence on animal welfare. The results revealed that stallion husbandry in groups is possible but still rarely practiced. It was found that 6% of stallions in 2003, more than 11% in 2012, and nearly 23% of the stallions in 2015 were kept in groups. Furthermore, studies showed that the still widespread individual husbandry of stallions has a negative impact on psyche and body health. Almost half of all stallions showed undesirable patterns of behavior, mostly stallions in individual housing. In addition, many of the latter stallions had problems with their respiratory, digestive, and musculoskeletal systems, which improved when the husbandry conditions of the horses were changed, with the exception of the problems with the digestive system. Conversion into group husbandry is possible, as revealed by an experiment by the Swiss National Stud with a socialization of active breeding stallions outside the breeding season. Therefore, the widespread fear of serious injuries for stallions housed in groups was refuted and the aggressive behavior of the stallions decreased rapidly. Success rates for group husbandry are influenced by the individual character of the stallion, previous experience of the stallion, changes in the group, qualification and management of the farm, and organization of the group housing and husbandry system. This enables species-appropriate husbandry in groups while also considering animal welfare without stress, disadvantages, and serious injuries for stallions.
