Possessive Aggression and Fear-Based Reactivity in a Neutered Male Shiba Inu: A Multimodal Behavior Modification Approach

Chewy, a castrated 2-year-old Shiba Inu, was referred for a documented history of possessive aggression resulting in six level-3 bites to familiar humans and multiple attacks on dogs. His early history included neglect, inadequate socialization, and punishment-based training using an electronic shock collar. He lived in a dense suburban town house with two owners, a female roommate, and a resident 10-year-old Chihuahua. Assessment revealed fear-based defensive aggression triggered by food and resource guarding, unexpected physical contact, loud environmental noises, and visual stimuli. A structured behavior modification program was implemented, incorporating environmental management, desensitization and counterconditioning (DSCC) to food bowl approaches and the vacuum cleaner, management protocols for strangers, and muzzle training. Chewy showed meaningful improvement across several months, including over 200 consecutive bite-free days. However, repeated lapses in owner compliance with management protocols, combined with cumulative risk factors including a punitive training history, multiple co-occurring phobias, and unpredictable reactivity to hand movements, contributed to two additional biting incidents. Following a serious bite sequence involving a teenager and the female owner, the owners elected euthanasia. This case illustrates the importance of owner adherence, structured follow-up, and honest prognosis communication in the management of dogs with complex, multi-trigger aggression histories.