Kathryn M. Wrubel, Alice A. Moon-Fanelli, Louise S. Maranda, Nicholas H. Dodman, 2011

Objective—To analyze factors associated with interdog household aggression and determine treatment outcomes.
Design—Retrospective case series and survey.
Animals—38 pairs of dogs with interdog household aggression. Each pair of dogs was considered 1 case.
Procedures—Records of dogs with interdog household aggression that were examined during initial or follow-up consultations at a veterinary teaching hospital from December 5, 2006, to December 5, 2007, were analyzed for clinical features. Data regarding outcome, owner compliance, and efficacy of recommended treatments obtained by use of a followup survey were evaluated.
Results—Most cases (30/38 [79%]) of interdog household aggression involved same-sex pairs; 26 of 38 (68%) cases involved 1 female or a pair of females. Instigators and recipients of aggression were clearly identified in 27 of 38 (71%) cases; most instigators were the younger of the pair (20/27 [74%]) or were newer additions to the household (19/27 [70%]). Fight-eliciting triggers included owner attention, food, excitement, and found items. Some dogs had risk factors for behavior problems such as a history of living in multiple households (21/51 [41%]), adoption after 12 weeks of age (20/51 [39%]), or being acquired from a shelter (17/51 [33%]). Effective treatment recommendations included implementing a so-called nothing-in-life-is-free program, giving 1 dog priority access to resources, and administering psychotropic medication. Frequency and severity of fighting were significantly reduced after consultation. Owners reported a 69% overall improvement following treatment.
Conclusions and Clinical Relevance—Most treatment strategies were considered effective. Consistency and predictability of social interactions are essential in resolving interdog household aggression.

Download full study below