Outcome: Among 222 surveys that met enrollment criteria, human-directed aggression that occurred on at least 1 occasion was reported in 64% (n = 142) and aggression that occurred once or more per month was reported in 31% (69). No significant differences were found in the prevalence of human-directed aggression among castrated males, sexually intact females, and spayed females. Ages of weaning and neutering and the presence of objects intended to serve as environmental enrichment were not associated with frequency of aggression. A significant inverse association was detected between presence of other pigs in the same household and human-directed aggression, such that 21% (20/95) of pigs that lived with at least 1 conspecific were aggressive on a frequent basis, compared with 39% (49/126) of pigs that lived with no conspecific. A similar inverse association was evident regarding aggression that occurred on at least 1 occasion.
Impact of the study: Results suggested that human-directed aggression is a common problem in miniature pet pigs. The presence of a conspecific can be expected to reduce the likelihood of human-directed aggression.
Publications: Tynes, V.V., Hart, B.L. & Bain, M.J. (2007). Human-directed aggression in miniature pet pigs. Journal of the American Animal Hospital Association, 230(3), 385-89. (DOI:10.2460/javma.230.3.385)