Dogs fight for a variety of reasons. Usually there is a dominant and subordinate dog and the owner should not interfere with the relationship.
On other occasions, neither dog is willing to be subordinate. This could be due to a challenge to the hierarchy as a younger dog matures, as an older dog becomes sick or aged, when a new dog is introduced into the home or when one dog is not clearly dom inant to the other. You should learn how to recognize canine body language and low-level threats such as eye contact, snarls or low growls. Keep records of threats, attacks or tension-producing situations. An owner must have excellent control over both dogs in order to succeed. To facilitate treatment, decrease the chances of injuries and increase owner control, a remote leash can be left attached to one or both dogs. Often the best form of owner control is to fit and train each dog with a head halter, and to leave a leash and head halter on each dog when they are together (under the owner’s supervision). In other cases, basket muzzles may provide more safety and allow owners to work with the dogs.
Once you have gained sufficient control over both dogs, and have identified the more dominant, you will need to deal with the circumstances that might elicit aggression. Greetings should be low key, and both dogs should be ignored. Treats are avoided and rawhides or other delicious things are not given unless the dogs are separated or on leash. Movement through tight spaces is avoided or controlled. You must be present to ensure that the dominant dog gains preferential access to food, resting-places, territory, owner attention and treats. Commands and rewards or the leash and halter can be used to ensure that the subordinate does not challenge, and that the dominant does not continue to show aggression once the subordinate submits.
Getting the dogs together without incident can best be accomplished when the dogs are otherwise occupied and when a confrontation is unlikely, such as during walks or feeding. It is usually best to have two individuals to walk the dogs (each person controls one dog) and not to allow them to forge in front of one another. During feeding, keep the dogs at a distance, far enough apart that they do not show aggression. Slowly the dishes are moved closer together as long as the dogs do not react. The food serves as a reward in this situation. If the dogs react, the food bowls are moved further apart. When the owner is not home or supervising the dogs, the dogs are separated or crated.
Basket muzzles could be left on each dog to increase safety while the dogs are together. They can also be used to “proof” the training, by putting the dogs together in situations that previously led to aggression. Drug therapy for one or both dogs may also be useful.
At times aggression may persist despite owner control and intervention. In those cases alternate living arrangements for one of the animals may need to be made.