Multi-cat households create welfare challenges from resource competition and social tension that cause stress, behavior problems, and physical health impacts when inter-cat relationships are poorly managed.
Multi-cat households with inadequate resource provision create chronic inter-cat stress that manifests as physical illness, behavior problems, and reduced quality of life for all household cats. The welfare cost of resource competition - guarded food, blocked litter boxes, prime resting spaces controlled by dominant individuals - is borne unequally by subordinate cats who may not access what they need. The N+1 resource rule directly addresses this welfare gap. Vertical space that creates non-competitive territories is one of the most cost-effective welfare improvements available to multi-cat households.