Interdog aggression is among the most common behavioral welfare problems in multi-dog households — evidence-based assessment and treatment substantially improve outcomes.
Interdog aggression causes welfare harm to all dogs in the affected household: the aggressor experiences arousal and stress, the target dog lives in fear, and the owner relationship with all dogs deteriorates. The welfare goal is resolution rather than mere management — creating a household where dogs can coexist with positive or neutral emotional states rather than chronic tension. Evidence-based treatment integrates behavioral assessment to understand aggression motivation, environmental management to reduce conflict triggers, behavior modification to change emotional responses, and pharmacological support where anxiety underlies the behavior. In cases of severe aggression or incompatible pairs, permanent separation or rehoming may be the welfare-optimal outcome — recognizing that forcing incompatible dogs to share space is itself a welfare failure.