When Your Own Dogs Fight Each Other
Fights between dogs in the same home often follow a pattern. What two US behaviour clinic studies found about triggers, risk and outcomes.
Written by thecanineledger
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If your dogs have hurt each other, or one attacks the other on sight, keep them apart and talk to your vet soon. A vet can treat wounds, check for pain or illness, and refer you to a veterinary behaviourist. Don’t put your hands between fighting dogs.
Our note: This advice is ours. Separating fighting dogs can get you bitten.
In a US behaviour clinic’s records of 305 pairs of dogs that fought at home, “Resource guarding was the most common fight trigger (222/305 [72.8%]).” (Feltes et al., Journal of the American Veterinary Medical Association 2020, abstract).
While fights between housemates can feel random, the studies point to patterns: what sets them off, which pairs fight, and which cases go badly. This page sets out what two clinic studies found.
1. Which pairs fight
Same sex, often female. In the 2020 study, “Most IDA pairs included at least 1 female dog (214/305 [70%]) and dogs of the same sex (188/305 [61.6%]).” IDA is interdog aggression.
The newcomer. “The aggressor was acquired after the recipient in 181 of 305 (59.3%) pairs.” Aggressors were on average 16 months younger than the dogs they targeted.
An older study agrees. A 2011 study of 38 pairs at a US veterinary school found that “Most cases (30/38 [79%]) of interdog household aggression involved same-sex pairs” (Wrubel et al., Journal of the American Veterinary Medical Association 2011, abstract).
What it doesn’t show. These were dogs brought to specialist clinics. Pairs that settle on their own aren’t in the records.
2. What sets fights off
Resources. Guarding was the top trigger in the 2020 study. The 2011 study lists “owner attention, food, excitement, and found items.”
Guarding at home. “Possessive aggression (guarding of physical resources) was the most common comorbidity for individual dogs (216/610 [35.4%]).” A comorbidity is a second problem in the same dog.
→ Resource Guarding · → When Behaviour Change Is Really Pain
3. When it goes badly
What counted as a poor outcome. The 2020 study defined it as “permanent separation, rehoming, or euthanasia of dogs”.
Warning signs. “Factors associated with a poor outcome included pairs of the same sex, history of bites that broke the skin, and aggression on sight of the recipient.”
The authors’ advice. Help should come “quickly for IDA pairs with a history of bites that break the skin or uninhibited attacks on sight owing to the high risk for a poor outcome.” They also say owners “should be advised to avoid same-sex pairs during preadoption counseling.”
Our note: The advice to avoid same-sex pairs comes from one referral-clinic study.
4. What helped in 2011
Improvement. “Frequency and severity of fighting were significantly reduced after consultation.” Owners reported “a 69% overall improvement following treatment.”
What was used. The treatments included a programme where dogs earn what they get, giving one dog first access to resources, and medication. We don’t name the programme or any drug.
What it doesn’t show. There was no comparison group, and the results came from an owner survey.
Our note: Giving one dog “priority access” rests on a rank idea that our alpha myth page questions.
Our note: Both studies are from US referral clinics, and the 2011 one is small.
→ The “Alpha” Myth: Why Dominance Training Was Dropped · → Training That Works, and Why: What the Evidence Says About Methods
5. What we could not verify
| Commonly said | What we found |
|---|---|
| “Let them sort it out” | Not tested. But bites that broke the skin were linked with a poor outcome, and the authors advise acting quickly. |
| “Male dogs fight most” | No. Most pairs in both studies included a female, and most were the same sex. |
| “The older dog starts it” | Usually not. Aggressors were more often the newer, younger dog. |
| “A quarter of cases end in separation or rehoming” | Not confirmed. The abstract we read doesn’t give the share with a poor outcome. |
Sources
- Feltes ESM, Stull JW, Herron ME, Haug LI. Characteristics of intrahousehold interdog aggression and dog and pair factors associated with a poor outcome. J Am Vet Med Assoc 2020. ⚠️ abstract read. Retrospective records review, 305 pairs, one US referral behaviour clinic
- Wrubel KM, Moon-Fanelli AA, Maranda LS, Dodman NH. Interdog household aggression: 38 cases (2006-2007). J Am Vet Med Assoc 2011. ⚠️ abstract read. Retrospective case series and owner survey, 38 pairs
Always confirm with your vet before acting on anything on this page.