Sometimes it can be at the least frustrating when your Dog seems to have a problem with another dog in your house or indeed one of your neighbours dogs and other times it can lead to your worst nightmare when the dogs inflict physical damage on one another. If you appear to have an ongoing issue with dog aggression towards other dogs it might be best to speak to a dog behaviour specialist or your local Vet.
Some reasons why dogs might not like each other:
Dogs persistently attempt to gain dominance over one another, whether male or female. It is part of their instinctive behaviour that when two dogs meet, they will use eye contact to observe the stature of one another. If one submits by lying down then the question of which one is dominant over the other is settled. If not, dominance is achieved by the dogs trying to mount each other until one rolls over and turns away. Until the eyes have completely turned away, surrender has not happened as the ‘losing’ dog may launch a sneak attack against the other.
Dogs can be very protective about their food and you should never try to interfere with a dog whilst they are eating as they may turn very aggressive. Other dogs should also not be allowed to approach a dog whilst they are eating for the same reason.
The same logic applies to Bones as with Food above. Remember to share food or bones between your Dogs depending upon size/weight.
Believe it or not, but two dogs may fight over their owners affection. Try to divide your affection amongst your dogs as fairly as possible.
The amount of exercise you can provide your dogs will significantly dictate their behaviour. If you do not exercise your Dog then they can have extremely high energy levels which can lead to aggressive behaviour.