Dogs fight over territory, to protect their perceived pack, and because of overstimulation. Despite how it may seem to humans, dogs do not fight for no reason at all. Dogs can do serious harm to each other during a fight or attack. In some cases, the injuries can even lead to death.
It's useful to desensitize both dogs to a muzzle over the period you're desensitizing them to each other (in separate sessions), so the first time you're ready for them to actually interact together you can muzzle them and be confident they can't hurt each other.
Therefore, when there is fighting between dogs in a home, it is more likely to be caused by conflict over resources, fear, pain and irritability, redirected aggression, or sociopathic tendencies (in which one or more of the dogs have underdeveloped or insufficient social communication skills).
While it seems dogs do forgive after a fight, there's still a lot more to learn about reconciliation in dogs. In some multi-dog households, it doesn't always work out. Shyan-Norwalt has observed dogs in the same family who did not reconcile but instead separated after every conflict.
Dog aggression can be related to fear, prey drive, socialization issues, and guarding territory, among other things. Most aggressive behavior in dogs stems from fear and anxiety, rather than the desire to hurt others. A certified animal behaviorist can help you safely deal with your dog's aggressive behavior.
Avoid triggers. You cannot expect your dog to behave until they have learned how. For example, if you know your dog has become more aggressive in high-energy play situations, stop going to the dog park until your dog has learned to remain calm. Reinforce calm behavior with rewards.
However, there's no guarantee that an aggressive dog can be completely cured. In many cases, the only solution is to manage the problem by limiting a dog's exposure to the situations, people or things that trigger her aggression. There's always risk when dealing with an aggressive dog.
Can dogs live together after fighting? The answer is, most of the time, YES. There are times when dogs may be like an incompatible couple and need to divorce, but in general, there are things you can do to help combative pups get along.
Punishment should never be used to train a pet. Pets should be taught what we want them to learn through reinforcement and shaping rather than attempting to train them what we don't want them to do. It is illogical to wait until the pet misbehaves and then administer something unpleasant.
Many serious injuries seen with dog fights are internal and dogs can have critical injuries with no outward signs of trauma at all. Anytime a dog has been in a fight they should see a veterinarian to look for pain/wounds or signs of serious internal injury.
Other tips and factors on aggression between dogs:
If a fight breaks out, try to startle the dogs with a loud “hey!” or clap your hands. Or you can try throwing water on them. Separate your dogs when they're home alone. Consider spaying/neutering.
In a real fight, the dogs will target the stomach, throat, and front legs and the victim of the attack will often retaliate by grabbing a hold of the other dog's neck. If your dog is involved in such a fight and receives severe injuries, take him to the vet immediately.
Fixing dog aggression is not quick or easy in most cases, but with the right dog training expert, it can be done.
You have to stay as calm as you possibly can. Don't: Panic or yell. Panic will do to a fight what gasoline does to fire - intensify it quickly. The slower you move the more clearly you will think and the easier you will “see” the fight and make good decisions.
Some have recommended that the dogs not be anywhere near one another for at least 48 hours following the fight, even if they live in the same household, while others recommend that getting a positive interaction between the two animals as soon as possible is the best course of action -- at the end of the day, however, ...
Punishment should not be used to correct undesirable behavior. Some pets may see it as a form of reinforcement, while others will become increasingly more fearful or aggressive. Punishment focuses on stopping the undesirable but does not teach what is desirable.
Walk and walk again
Never punish your dog by yelling at or hitting them; this will only perpetuate the behavior and make them fearful of you. If they react calmly, continue lavishing them with treats and praise so they know they're on the right track.
Dogs that continue to attack each other, even after training, should be separated permanently.
Medication is an often-underutilized tool that can greatly help with managing aggression in dogs, according to veterinary behaviorist Dr. Karen Overall.
If your dog is showing any changes in their behaviour, especially if they have started showing aggression suddenly, you should contact your vet as soon as possible. Aggression tends to get worse over time and can lead to serious injuries to you, your dog or other people and pets so getting help is essential.