Evaluation of a Young Dog for Escalating Aggression Toward Both Familiar and Unfamiliar People

This case report describes the evaluation and successful multimodal treatment of severe, early-onset aggression in a juvenile dog. A 9-month-old spayed female Australian Shepherd presented with escalating aggressive behaviors toward familiar and unfamiliar people, including multiple bite incidents resulting in human injury. Aggression was observed across numerous contexts, including handling, play, resource guarding, visitor interactions, and encounters with people and dogs outside the home. Significant risk factors included early removal from the dam at 6 weeks of age, minimal early socialization, a history of chronic illness during early development, and later-discovered aggressive traits in both parents. Comprehensive medical evaluation, including repeated laboratory testing and neurological assessment, revealed no underlying medical abnormalities. Behavioral diagnoses included generalized anxiety, impulse-control aggression, fear-related aggression, possessive aggression, and socialization deficits. Prior to referral, behavioral issues were minimized by outside advisors, and no psychopharmacologic intervention had been attempted due to the dog's young age. By 9 months, the family was considering rehoming or behavioral euthanasia due to safety concerns and breakdown of the human-animal bond. Treatment consisted of an integrated plan incorporating environmental management, strict safety protocols, positive reinforcement-based behavior modification, and pharmacologic therapy with fluoxetine and gabapentin. Within 6 weeks, the family reported moderate improvement, with marked and sustained improvement following dose adjustments and continued behavior modification. By 14 weeks, aggressive incidents had substantially decreased, and after 1 year of therapy, bite behavior had resolved. Long-term follow-up demonstrated stable improvement, improved tolerance of veterinary handling through cooperative care training, and restoration of household safety and quality of life. This case highlights the importance of early recognition, comprehensive assessment, and timely use of combined behavioral and pharmacologic interventions in juvenile dogs with severe aggression, emphasizing that young age should not preclude appropriate treatment.