how do I address resource guarding and inter-cat aggression in a multi-cat household?

Question

Accepted Answer

Inter-cat aggression and resource guarding are addressed through simultaneous environmental restructuring, behavior modification, and pharmacologic intervention — not sequentially. Because cases can take 2 to 12 months to resolve, all treatment pathways should be initiated together rather than waiting to see if environmental changes alone are sufficient.28 The first and non-negotiable step is complete physical separation of the cats until medication and behavior modification are underway. This prevents ongoing rehearsal of aggressive behavior and reduces cumulative stress in all household cats.2 Intercat tension affects 62.2–87.7% of multi-cat households, and 73.3% of cases begin at the introduction of a new cat, making the separation-and-reintroduction framework the backbone of management regardless of how long the cats have cohabited.9 Resource provisioning follows the rule of one station per cat plus one additional station as a minimum. Food bowls, water bowls, and litter trays should each meet this threshold, and stations must be distributed across multiple locations — not clustered together — so that one cat cannot block access to all resources simultaneously.57 Insufficient resource availability drives chronic stress and increases urine spraying, displacement behaviors, and feline stress cystitis.5 Note that simply providing an adequate quantity of resources does not guarantee conflict reduction; litter box size, type, and prior use, as well as the provision of resting and hiding locations, are also relevant variables that quantity alone does not address.3 Pharmacologic treatment starts with fluoxetine as first-line medication for inter-cat aggression. Punishment techniques — including water spraying — are strongly discouraged and actively worsen outcomes by increasing anxiety; positive redirection using food rewards is the appropriate intervention during aggressive events.26 Owner education on appropriate intervention tactics alone, delivered before any pharm