Sibling rivalry refers to conflicts between dogs living in the same household.
Sibling rivalry arises between dogs when there is instability in the dominance hierarchy. That is, when the social position of each dog is not clear or is in contention.
Dogs usually establish their dominance hierarchies through a series of ritualized behaviors that include body postures and vocalizations. This ranking is based on the behavior and view of the dogs, not what ranking you prefer. You cannot choose which dog you want to be alpha. Dogs will establish this among themselves, and any attempt to interfere may result in increased sibling rivalry.

Prevent sibling rivalry - permit your dogs rules.

You need to respect and support whatever "dominance hierarchy " your dogs establish for themselves.

• Alpha dogs must be allowed to take toys away from subordinate dogs, to push in to receive attention from the owner, to control favorite sleeping places, food, and other valuable resources. Support the alpha dogs status by allowing this to occur.
• Do not undermine their hierarchy by attempting to treat the dogs equally and democratic, or by preventing the alpha dog from asserting his position.
• Do not stop the expressing of signals and ritualized behaviors that establish dominance, like snarling, growling or snapping. For us humans it looks and sounds worse than it is. They only do it to impress the other dog, to get its respect.
• Do not protect the subordinate dog, because he is younger or smaller.
• Always, without exception, the alpha dog gets the preferential treatment. He gets his food first, you pet him first, he goes into the car first, with him, you play first, and he is groomed first…
• Never, attempt to break up a fight between dogs.

These rules are valid not only in your house, but also in the park, at the beach, at the vet. Whenever two dogs approach, open the leash let them sniff each other, and try not to hinder their communication.

Because inadequate puppy socialization or temperament tendencies some dogs may escalate into serious aggression. If you have to break up such a fight, do so by squirting them with a hose. Alternatively, throw a blanket over the heads of both dogs to confuse them.