Dr Liesel van der Merwe is a small animal medicine specialist. Send her your questions: This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Dr Liesel van der Merwe

Vets almost daily see dogs with bite-wounds. It’s short-sighted of both vet and owner to fix the wounds without dealing with what caused the fight, as the scenario will just play itself out again.

I did some reading up to test my own theories. Typically one dog will instigate the fights, often the younger dog or a newer addition to the household. Fights may occur between dogs of any sex, although earlier literature found mainly same-sex pairs involved in aggression. The prognosis for successful behavioural interventions is decreased if bite-wounds break the skin, if it’s a female pair and if there is aggression on sight of the victim.

Fight-causing triggers include physical resources such as food or beds, owner proximity or attention, confined spaces and excitement, which may occur during play, walks, greetings or car rides.

A large study listed the following as triggers: owner attention was most common, followed by food, excitement and found items (toys, bones, chews). Other triggers included loud noises, passing through doorways, sharing walkways and the presence of visitors.

Alliance aggression is where dogs only fight in the presence of their owner and live peacefully together when alone. Fights will occur around greetings, in door- and gateways where both try to get through simultaneously to greet.

Fighting may be an attempt to establish hierarchy when circumstances change. This can be a new addition, the death or declining health of an older dog or the social maturity of a younger dog. We think of hierarchical structures as those pyramid diagrams with the CEO on top, but this is not how it works with dogs. 

Studies of free-ranging dogs have found that there are very few fights between members. Subtle communication by growling and body posture is clearly understood by the target dog. Hierarchies may also change depending on what the group is doing, so that the best dog for the job becomes top dog for the duration.

Homes cannot be considered a normal environment for dogs. They are in a restricted area, cannot roam or move away from threats. Resources are limited and controlled, which may cause anxiety. Important members of their pack, the humans, often respond inconsistently to the same actions, thus causing anxiety. Dogs are very sensitive to favouritism.

A study found that many dogs were also diagnosed with separation anxiety, generalised anxiety and showed fear behaviours in social interactions. Anxious dogs have a reduced threshold for aggression. We may make our dogs more anxious than we realise. I can see this in my own dogs. I adopt adult dumped or found dogs. The less you interfere with them as they get to know each other or as conditions change, the better they will manage.

Behavioural interventions proposed are: ranking the dogs in the order they receive resources and sticking to it and a program which makes dogs work for their resources. The program aims for better communication and consistent interactions between owner and dog. It is not about dominance behaviour towards the dog, but more about methods of response and reward, such as sit or stay. Rewards are food, attention and petting.

Ranking the dogs would generally support the younger, healthier and larger, more confident dog, which is usually the aggressor. An alternative is a senior-support approach, where the oldest dog or the dog which has been there the longest receives resources first. 

I always feed my dogs in a certain order, and they need to wait, each at their spot, for the bowl to be placed. I do not create excitement around feeding: voice tone is low and calm and if everyone is too excited, there is some down-time before everyone gets fed. Making dogs which fight wait in a controlled manner while a resource is present could diffuse tension. Greeting on arrival should also be delayed and not high-pitched and excited. Only greet dogs when they have calmed down.

We underestimate the tensions and anxieties our dogs feel within our homes. In many cases of fighting, it is not innately aggressive behaviour but rather anxiousness which tips over into aggression. We can successfully manage many of these situations with improved consistency and predictability and allowing them space to have their own interactions.

Think of your dogs as hypersensitive, hormonal, insecure, easily slighted teenagers: they need grounding, consistency, clear guidelines and boundaries and then to get on with their own things