Remember that if you have more than two dogs, several dogs can gang up against one dog and may not stop until that dog is dead. Packs may turn on
their own if the victim is old or sick, and occasionally they will even turn on the very young. Protect puppies, geriatric, and ill dogs by keeping them separated from stronger pack members when you're away from home and with supervision when you are home.

Here's one thing you might try if you have one perpetrator and one victim. Do you wear a particular cologne or hand lotion? Try applying your scent to the victim for a week or two and see what happens. Dogs are VERY scent-oriented. You smell like love, warmth, food, water, all the good effect of stopping aggression and building friendships. This works with cats, too.

Remember that in a pack situation, a dog may act out by chewing, soiling, or displaying other troublesome behaviors. These may be a result of something you did, changes in living arrangements or schedules, additions or subtractions of family or pack members, or simply a response to another dog's actions. Sometimes it's hard to guess why things aren't going right, so don't always blame yourself.

Each dog is different. Each situation has to be independently evaluated. If dog fighting in your home is just an occasional nuisance, do what you need to do to live with it and prevent fights. However, if the situation is making your life or your dog's life miserable, be willing to carefully place a dog with another loving family and get back to having a harmonious home. Life's too short to be miserable, and your dog's life is even shorter. Make sure it's a good one. If you place one dog, be alert to changes in pack dynamics. Another dog might try to take the first dog's place as antagonizer. 

- Know in your own mind the differences between what you will tolerate and what you will not. Set your house rules and stick to them. It's your life, your house, and your dogs. Within the bounds of being reasonable and fair, within the bounds of humane treatment, it's your call.
- Don't worry about being alpha; just be clear within yourself and your dogs will know you are the boss.
- Keep learning.
- Observe your dogs carefully.
- When in doubt, it's better to be safe than sorry. Don't take risks, especially with a dog who has fought or bitten before. Use adult supervision, leashes, neutering/spaying, closed doors and gates, or whatever is needed.
- Experiment; if what you're doing isn't working, try something else. Try to give changes time to work.
- Use your clicker and treats to reward behaviors you like.
- Don't drive yourself crazy trying to figure out what a dog is thinking.
- Don't beat yourself up crying over mistakes you think you may have made. Life goes on.
- All's fair in love and war, and that includes breaking up a serious dog fight with a broom, or whatever means you can find. An emergency is an emergency.
- Be good to yourself. Take breaks. Take a bubble bath. Take a vacation.
- Don't do anything against your better judgment, no matter who said to do it. Trust your observation and intuition above all.

INTRODUCING A NEW DOG TO THE RESIDENT DOG(S)

Keep them separated from one another initially, using crates.   There’s no point in setting the new dog up for failure.  If he’s quiet and good in his crate, reward him with treats for his good behavior, and simply ignore him if he’s putting up a fuss.  Use a baby gate to help keep the dogs separated through the initial introductory phase. 

Walk them separately in the beginning.

When one is crated and the other is free, reward them both with treats for good behavior and a calm response to the other dog.  Rewards work better and have a much longer impact on a dog than reprimands.

Feed one dog in his crate and the other in another room or another crate, so neither feels threatened by the other when there’s food involved.   The same advise applies to high value toys and treats.  Keep them separated and do not allow a rivalry to develop.

If there doesn’t seem to be a huge problem between them, you can begin to walk them together, on opposite sides of the street.  After that has gone well for several days, then you can allow them to meet on neutral ground, such as a nearby park.  If that goes well, then they can walk home side by side, and have their walks together after that.  It will still be too early to allow them to be together in the house – give them a few days of enjoying their walks together. 

Once that is going well and they’re looking forward to seeing one another, then you can carefully let them meet in the house, preferably when there are two adults present.  USE A LOT OF TREATS to reward them when they’re good, just be very careful not to inadvertently introduce food aggression at this point.  Give each of them the SAME treat at the SAME time and do not allow either of them to try to steal the other’s treat.  Collars and leads would be quite useful at this point, just so you have a way to maintain control of the situation if it appears to be getting out of hand.   Remember, outdoors is one thing – in the house is a totally different environment for a dog, and one or both of them might be protective about having an “invader”.  That’s why it’s important for them to get to know one another on neutral ground and to see one another in the house (but safely apart from each other) for a while.  It will be much easier on both of them (and you and your family) if you take the time in the beginning to introduce them carefully.

This can be quite a lengthy process – up to two months – so don’t rush the dogs into a situation that they might not be ready to handle.

What Is Canine Rivalry?
Canine rivalry refers to repeated conflicts between dogs living in the same household. Animals that live in social groups establish a social structure within the group called a dominance hierarchy. This dominance hierarchy normally serves to maintain order, reduce conflict and promote cooperation among group members. Conflicts arise between household dogs when there is instability in the hierarchy, that is, when the ranking or social position of each dog is not clear or is in contention. Initially, dogs may only snarl, growl or snap without injuring each other. Sometimes, however, the conflict may intensify into prolonged bouts of dangerous fighting which may result in one or both dogs being injured.

Getting Professional Help
Ongoing canine rivalry is potentially dangerous since the dogs could be severely injured, as well as family members, if they become the object of redirected aggression when the dogs are fighting. Because resolving rivalry problems requires managing the dogs’ somewhat complex social behaviors, it’s often necessary for owners to obtain assistance from a professional animal behaviorist (see our handout: "When the Behavior Helpline Can't Help"). Animal behaviorists are trained to observe, interpret and modify animal behavior.

Why Conflict Occurs
Conflicts between household dogs usually develop when the ranking of each dog is not clear or is in contention. This may occur if:

You attempt to treat both dogs equally, rather than supporting the dominant dog’s position.
You interrupt or interfere with the dominant dog's ability to control the preferred items (food, toys, beds, attention) in his environment by giving preferential treatment to the subordinate dog(s).
You prevent the dogs from expressing the signals and ritualized behaviors that establish dominance.
A new animal has been introduced into the house.
A resident animal has died or no longer lives in the house.
A resident animal is re-introduced after an absence.
A young, subordinate dog reaches social maturity (usually between ten months and two years of age).
A dominant dog ages and cannot maintain his dominant status.

Understanding Dominance Behavior And Social Structure
You cannot choose which dog you want to be dominant. The dogs will establish this among themselves, and any attempt to interfere may result in increased conflict. Where each dog ranks in the dominance hierarchy is determined by the outcomes of interactions between the dogs themselves.

Determining which dog is dominant: Individual personality, as well as breed characteristics, are important factors. The dog that demands to be fed first, petted first and through the door first is usually the dominant dog. Remember that the rankings may be different in different contexts (one dog may control food, while another may control resting places) and they may change over time.

How dominance is established: Dogs usually establish their dominance hierarchies through a series of ritualized behaviors that include body postures and vocalizations that don’t result in injury. One dog may "stand over" another by placing his paws or neck on the shoulders of the other. However, because of past experiences, inadequate socialization or genetic temperament tendencies some dogs may, with very little warning, escalate dominance displays into aggression. If this occurs, call  your veterinarian for a referral to a professional animal behaviorist.

Dealing With Rivalry Problems
If the dogs involved are intact males or females, spay or neuter both dogs.
Determine each dog's dominance status relative to each other. Remember, this ranking is based on the behavior of the dogs, and not what ranking you prefer.
Support the dominance hierarchy. You need to support whatever dominance hierarchy or "pecking order" your dogs establish for themselves. Don't undermine their hierarchy by attempting to treat them equally or by preventing the dominant dog from asserting his position. Dominant dogs can, and should, be allowed to take toys away from subordinate dogs, to push in to receive attention and petting from the owner, to control favorite sleeping places, toys and other valuable resources (from the dogs’ point of view). Support the dominant dog's status by allowing this to occur.
Make sure that all of the humans in your household occupy the top of the dominance hierarchy by practicing "Nothing in Life is Free". This provides stability at the top of the dominance hierarchy, which will help the dogs sort out their lower places in the pecking order more peacefully.
Never, under any circumstances, attempt to break up a fight between dogs by grabbing their collars or inserting any of your body parts between them. If you feel you must break up a fight between dogs, do so by squirting them with a hose (outdoors), or squirting them with a vinegar/water mixture from a squirt bottle (indoors).

With the help of a professional animal behaviorist, elicit and reinforce non-aggressive behaviors using counter conditioning and desensitization techniques. These procedures must be designed and tailored to specifically meet the needs of each individual case and require professional in-home help.
You should be aware that if you respond to this type of problem inappropriately, you run the risk of intensifying the problem and potentially causing injury to either yourself, your dogs or both.

Punishment Will Not Solve The Problem
Punishment can actually make the problem worse. We encourage you to seek assistance from your veterinarian regarding: spaying and neutering your pet; evaluating the health status of your dogs; and for a referral to a professional animal behaviorist.