Research Report: Dog-Dog Aggression in the Household
Canine housemate aggression is a serious behavior problem in many dog households. Accurate reporting of the incidence of housemate aggression is challenging. Few owners report fights between housemates to the veterinarian. Presentation for bite wound care is often the first indication to the veterinary staff of housemate aggression. The medical prognosis for a level 3 bite is good, yet there is little information on the behavior prognosis for a situation where intra-household aggression has resulted in a level 3 bite.b
Often owners treat these wounds at home. Without intervention, the aggressive behavior often continues to escalate, resulting in more injurious bites. As a general practitioner with behavior expertise, I would warn that any aggression was serious and needed immediate intervention.
Until recently, there was little information about risk and prognostic factors for intra-housemate aggression. A retrospective survey of intra-housemate aggressive canine cases was published in the Journal of the American Veterinary Medical Association in February 2020.1
Drs. Feltes, Stull, Heron, and Haug reviewed 305 housemate pairs for various characteristics and behavior outcomes. Previous survey data indicated female-to-female pairs, and new additions to the household were common presentations for aggressive behavior.2 This survey looked at behavior success outcomes and case presentation criteria to determine what factors were positively indicative of a successful outcome. The survey results are as follows:
- 70% of pairs had one female, with 61% being pairs of the same sex
- Resource guarding was a trigger in 72.8% of the cases
- The aggressor was acquired after the recipient in 59.3% of the cases
- On average, the aggressors were 16 months younger, and 3.3 lbs. heavier than recipients of the aggression
- Level 3 bites, and unprovoked attacks, resulted in poor outcomes for behavior success
Bites that break the skin were an important factor for predicting a high likelihood of future attacks and bites, despite human household members actively attempting to manage the aggressor’s triggers. The correlation between bites that break the skin, and low success in preventing future aggression, means that veterinarians should consider bite wounds as a signal for immediate behavior referral and intervention.
Even when a dog is presented for an unrelated medical issue, if they have healed nicks and wounds that indicate a history of fighting with another dog in the owner’s household, I would suggest that the veterinary staff must immediately refer to a certified veterinary or animal behaviorist, and record this in their medical record.
It is equally important that non-veterinary behavior consultants refer to the primary care veterinarian when they are presented with intra-housemate aggression, as the possibility of attacks despite behavior management is a health and welfare risk on the victim dog.
As a veterinarian, I seek evidence to support my evaluation, advice, and prescription of care for medical and behavior problems. Veterinary behavior science continues to grow with research and studies to build our knowledge. The results of this retrospective survey give specific criteria for emergency and general practice veterinary staff to refer for behavior consultation. Canine health and welfare can improve with this additional knowledge.
Shelter staff can use the information from the Feltes et al. study to continue improved housemate adoption criteria. Intra-housemate aggression is a common behavior problem cited by owners relinquishing their dogs to a shelter.3 Post-adoption support for behavior can improve new adoptee retention.4 Many dogs have been placed into foster homes because of the covid-19 shutdown — with more people working from home and available to provide foster homes, coupled with shelters working to reduce their population to keep their staff safe and continue to operate despite not being able to use volunteers. Shelters should take this as an opportunity to review the dogs’ behavior in these placements, and screen for any brewing housemate aggression problems so they can offer support and advice. Veterinary staff should also use the study data for better resource management advice for aggression prevention, as resource guarding was one of the strongest predictors of aggression, but also correlated to successful outcomes for managing the problem.
I am very encouraged by this study, and I look forward to more surveys in the future. Risk factors and prognostic data for behavior problems provide veterinarians the numbers they need to confidently advise for behavior referral. Animal behaviorists can use the same data to inform and advise for veterinary support to the behavior plan knowing the impact on victim health and welfare in housemate aggression cases. This is one way to continue to build the bridge between veterinary and non-veterinary behaviorists.
References
- Feltes, E., Stull, J. Herron, M. and Haug, L. Characteristics of intrahousehold interdog aggression and dog pair factors associated with poor outcome. American Veterinary Medical Association website, accessed 6/2020.
- Dodman, N. (2011) Interdog household aggression: 38 cases. Journal of the American Veterinary Medical Association 238:6, 731-40.
- Donaldson, J. (2000) Behavior problems and long-term housing. Maddie’s Fund website, accessed 6/2020.
- Gates, M., Zito, S., and Dale, T.A. (2018). Post-adoption problem behaviours in adolescent and adult dogs rehomed through a New Zealand shelter. Animals 8:6, 93.
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Mike is an emerging animal behaviorist sitting in Minnesota in the US. He carries an MSc in social science research methods (U. of Kentucky) and brings a passion for understanding how the methods we favor shape the knowledge we privilege. Coming from careers in teaching and non-profit program evaluation, he found companion animal behavior by accident helping anxious feline friends in a unique shelter in Ohio. It is a privilege and a joy to combine these and advance the journal in this exciting time of growth.
Alexandra is a certified dog behavior consultant and holds a PhD in neuroscience. She has spent over a decade in academic research and is author of numerous scientific articles on different aspects of brain development, including olfaction, neurogenesis, and memory formation. Her work as a behavior consultant focuses on creating trusting relationships between humans and their dogs through communication, respect, and science-based knowledge. Alexandra is very dedicated to promoting more science within the dog training world. She supports dog guardians and professionals to build a solid understanding of scientific principles and provides guidance on how to apply these to life with dogs. She runs Canine Mindscape in Alicante, Spain.
I’m an Argentinean-Italian dog trainer and CSAT who spent eight amazing years in Brazil learning and working with dogs. Now based in Europe, I volunteer with the IAABC as a translator and, in my free time, help rehomed dogs settle into their new families. I love bridging languages—and hearts—between people and their dogs.
I’m a translator, editor and journalist, as well as canine educator for children and families, specialized in canine body language. I am part of the IAABC Family since 2019, as Language Director at the IAABC and Translators Team Lead at the IAABC Foundation, at the moment. I volunteer at local shelters and promote bite prevention and animal welfare at schools and events all over my country, Uruguay.
I’m a Chilean veterinarian and certified dog trainer, based in Madrid and working at a veterinary clinic. I’ve been volunteering with the IAABC and the IAABC Foundation for over seven years. In my free time, I help dogs and their guardians strengthen their bond, and I love spending quality time with my own dogs.
Master’s Degree in Natural Sciences, with a strong interest in environmental sustainability and the protection of natural ecosystems. Passionate about writing and science communication, she collaborates with multidisciplinary teams on research projects, such as Equine International, and with non-profit initiatives in the environmental and cultural fields. She is writing for different magazines, including IAABC Foundation. Her major goal is to improve horse’s welfare through behaviour research and empirical practice.
Adrienne Hovey is the copy editor for the IAABC Foundation journal and the owner of 
I believe that knowledge from a wide range of disciplines fosters a more empathetic, curious, and engaging world. I am passionate about social, environmental, and minority rights issues (both human and non-human), and this has invariably led me down the road of multi-species anthropology. Perpetually curious about the world we live in, I hope to contribute towards making the world a kinder place for all of us earthlings to live on!
Beckie Wheldon is based in England, UK, and has been supporting the IAABC Foundation Journal team as a volunteer journal content editor since early 2025. She has a BSc (Hons) Animal Behaviour and Welfare, and has recently completed a MSc Clinical Animal Behaviour. With a passion for both practical and theory, Beckie is proud to be a part of the journal submission journey and support the process of applied animal behaviour information and research getting from our writers to the readers. As her full-time career, Beckie is currently part of the UK veterinary charity, PDSA, as a Learning and Development Business Partner for Veterinary, where she supports the professional development of people in their Veterinary Hospitals. Her last position was with the rescue charity, Dogs Trust, as a Canine Behavioural Welfare Manager, where she worked on embedding evidence-based behavioural welfare best practices throughout policy and practices, with both internal and external professional stakeholders, such as the police and military. With a varied background in kennels, caregiver education, and charity dog training classes, Beckie is also an accredited Animal Training Instructor (APDT UK) and an Associate Clinical Animal Behaviourist (APBC).
Erin Jones, PhD, IAABC-ADT, CDBC, CPDT-KA, CANZ-ATI, CANZ-ABC, is the Journal Director of the IAABC Foundation Journal. She holds a PhD in Human–Animal Studies, an MSc in Anthrozoology, a PG Dip in Animal Welfare, and a BSc (Hons) in Anthropology and Psychology. An international presenter, editor, writer and mentor, Erin’s writing bridges research and practice with a focus on the intersection of philosophy, ethics and dog-centered behaviour practice. She is the author of Constructing Canine Consent and co-editor of Topics in Non/Human Coexistence and numerous academic and trade journal publications.