I recently saw a very interesting case of two dogs in the household fighting with each other. The older dog is 5 years old and the owner has had him since he was 10 weeks old. The younger dog is 13 months old and has lived with the owner since he was 4 months old. According to the owner, the younger dog began to attack the older one about 4 months ago. Over a short time, the attacks increased in frequency to several times a day and were so upsetting to the owner that she explored the possibility of re-homing the younger dog. She saw our appointment as his last chance to stay in her family.
There are many reasons one dog may attack or be aggressive toward another: He may be guarding a very valuable resource (rawhide, toy, etc.) and think the other dog wants it. He may be of a breed that has been selected for dog aggression. He may have been poorly socialized to dogs. He may have had bad prior experiences with this particular dog.
But, for two dogs that live in the same house, the most common type of aggression is called “Dominance-Status Aggression” (DSA), also sometimes called “sibling rivalry.” In this setting, the dogs know each other well, and get along very well much of the time. Generally one dog is consistently the aggressor and the fights/attacks happen most commonly when the owner is present. Other possibilities for two household dogs fighting include pain/injury, illness, territorial aggression, or maternal aggression.
So, what causes DSA and what can be done about it?
Causes of DSA.
Usually, the owner is the cause. It is over-simplistic to say this; but, the reality is that the average dog owner will often completely ignore his dogs’ social hierarchy and attempt to impose what he believes to be equitable. This leads to tension between the dogs, which then leads to aggression when the owner is present.
What does it mean for dogs to develop a hierarchy? Speaking generally, dogs have a flexible but fairly strong social structure, in which one dog is the most dominant, followed by a more subordinate dog, then the next most subordinate, and so on. If you are watching a group of dogs that know each other well, you will see which one has easiest access to the best resources (toys, treats, lounging spaces, etc.); this is typically the most dominant dog in the group. The dog that most willingly gives up resources is generally the most subordinate. The others fall in line in the middle. This is a gross generalization (and some very subordinate dogs will fight for certain resources); but the principle is reliable.
Unfortunately, owners have their own sense of fairness. Usually, they give the older, more frail, or most beloved dog the best of the resources and the most attention, regardless of his status in the group. This is a perfectly human thing to do. Yet, if the owner chooses to lavish attention and resources on a less dominant dog, the more dominant dog may feel compelled to put the favored dog in its place, through growling, biting, or other aggressive act. The owner, who generally responds negatively (yelling, scolding, or other form of punishment) to the aggressor, may increase his attention on the attacked dog, thus escalating the problem.
What about two dogs that start fighting suddenly after having been “fine” with each other for months. If a younger subordinate dog is becoming socially mature or a previously-dominant dog is failing in health, there may be the opportunity for a shuffle in the dominance hierarchy. If the owner inadvertently lavishes attention on the wrong dog, there can be aggression as a result.
It should be noted that not all dominant dogs care enough to interfere with the owner’s interactions with the other dog.
Treatment of DSA.
Often, treatment is as simple as correctly identifying the dominant dog and supporting him as such. This is accomplished by giving him the most attention, providing him with better resources (nearer the owner on the bed or sofa, first access to the house or yard, etc.), and asking for less “work” (aka fewer commands) before giving him things. If the dominant dog has to sit for his dinner, the other dog must sit and shake paws before the food dish touches the ground. If a battle does break out, owners should leave the room, as their presence is typically required to fuel the conflict. Under no circumstances should either dog be punished for his actions.
If one or more of the dogs is unneutered, surgical intervention in the form of spaying or neutering can also help relieve some tension.
Owners are occasionally resistant to these changes, because they have been favoring the subordinate dog for a reason. But, when they see the difference their actions can make to the stress level in the house, they usually come around. They also get creative about spending quality time with their favored pet without the other being aware.
Dominance within the hierarchy is determined by some combination of health, age, size, sex, and overall confidence. But, what if you have two dogs of the same sex from the same litter? You have two dogs that are likely equal in most factors that determine hierarchy. As they come to social maturity, one of three things may happen: If they are pretty mellow, they may never establish an obvious hierarchy and be perfectly willing to share the lead. If one cares more than the other, he may simply declare himself dominant without contention. Or, you may have a situation in which the two dogs spend their adulthood struggling for dominance, possibly without resolution. This is a particularly challenging situation for which there is no simple solution.
In the case I saw, the owner was amenable to making changes in the way she treated the dogs. She was not excited to reward the “upstart” in favor of her long-time companion. But she saw the merits. She also saw the tension between the two dogs melt away. One month later, the two dogs rarely scuffle and the owner is delighted.