I have a sibling, whom I love. When we were young, we used to fight quite a bit. I was jealous of his privileges, such as a later bedtime or staying out later. Some of our fights were bad and on occasion one of us, usually me, got hurt. Our fighting continued until I matured a bit. Thankfully we haven't fought since I was maybe six or seven. Dogs living together sometimes also fight, although jealousy is never the reason. Jealousy is a human emotion not a canine one.
Sibling Rivalry is one of the most serious issues people with their dogs. This can be somewhat of a misnomer as most of the time, the dogs are not truly siblings and often they are not even the same breed let alone the same litter. But they are dogs living together.
There can be several different reasons it happens and before working on a solution, we need to understand the cause(s):
Avoiding Pain
One common reason for sibling rivalry is that one dog, often a senior, has some health issues and a younger dog either tries to take advantage or possibly even inadvertently hurts that dog. The older dog might become defensive as a strategy to avoid further injury or pain. Dogs sometimes will take the offensive course in these situations.
No Pack Leader
Another common reason dogs living together fight is that they don't have what they perceive as any or weak leadership from the people they live with. The clear majority of dogs are born followers, not born leaders. They seek direction and guidance from those they live with, both canine and human. If they do not perceive there is any leadership, they will, to the best of their ability try to be the leader. As with people who are put into positions they are not suited to, when dogs are not suited to be leaders but inadvertently try to assert themselves, they are likely to make mistakes. If two dogs of similar temperament are both trying to assert themselves, it can lead to serious issues.
Likewise, if a subordinate dog is being favored over a dog with more natural authority, that can also lead to problems. Dogs always establish their own rankings between themselves and under most circumstances this is done without being physical. However if a subordinate is being elevated by the people, the dog higher in the ranking is more likely to take offense.
It is human nature for pet parents to favor an older dog that has lived with them a longer time and let them "get away" with things they don't let a younger one do. This can lead to unequal rules such as allowing one on the furniture or in the bed, but not the other. Depending on the dogs involved, this may, or may not be an issue.
Favoritism or Inconsistency
The more times that the dogs fight, the more difficult it will be to fix and sometimes, even after everyone's best efforts, the best solution for both the dogs and the people is to re-home one of the dogs.
Bark Busters has had great success helping their clients solve sibling rivalry issues, but the solutions always begin with a thorough investigation to understand the causes. All the relationships between all the people in the family and all the dogs need to be explored. Health issues, diet and even the environment can be factors. Only when the causes have been determined can a plan of action be developed. There is not a one size fits all solution.
People will often go online and read lots of articles and try different approaches that are rarely successful. The problem with this approach is that the articles are not talking about your dog, your relationships, your home environment, or your life. The articles and information is general or is based on a specific set of circumstances and have nothing to do with what is happening with anyone's specific dogs.
If your dogs are fighting with each other, don't wait, call Bark Busters immediately. The sooner you get expert help, the better the chance of fixing it and not having things escalate.