Housing entire boars in groups presents significant welfare challenges from aggression and injury, but is required by animal welfare standards in some countries, demanding careful management of mixing and space.
Boar group housing presents a genuine welfare dilemma: the social motivation of pigs suggests group housing is preferable to isolation, but the aggressive territorial nature of entire males means groups of adult boars cause significant injury to each other. Wild boars establish dominance hierarchies through fighting that results in clear dominance relationships reducing subsequent aggression, but these fights themselves cause welfare harm. In commercial housing, space constraints prevent the avoidance behaviour that wild boars use to defuse conflicts — animals that cannot escape pressure continue to be targeted after initial dominance is established. Stable groups formed before puberty show substantially lower aggression than groups of adult strangers mixed for the first time. Visual barriers that break lines of sight reduce rank challenges in established groups. Individual housing with olfactory and tactile contact through adjacent solid-sided pens may represent the best welfare compromise for adult breeding boars, providing social stimulation without the injury risk of full group access.