DISCLAIMER: No matter how much and how well you do it, socialization cannot erase genetics. Even the most well socialized and trained dogs can be dog-aggressive. They may be under control and polite, but given the unhindered chance, they'd still engage in a fight. The main purpose of socializing your pit bull is to help him become well rounded, used to (unfearful of) many types of people, distractions and other animals, and to teach him to control himself around these distractions. It is NOT about forcing him to be friendly and play with other dogs, and it's not about "socializing away" dog aggression. That simply cannot be done.
Begin early training using positive reinforcement. Work on keeping your pup's attention around distractions. Teach him from day one to focus on you in the presence of distraction, other people and animals. "Leave it", "come", as well as "sit n' stay" and attentiveness are the four things you should focus on most in the beginning. Practice these things at home with no distraction, then begin to add mild distraction and change location so your pup learns to behave in a variety of situations.
Once the pup has a full set of shots, it's time to get him out and about as much as possible. Remember, the optimal time for socialization is between approximately 7 and 12 weeks of age. Getting your pup around a TON of people, all different shapes and sizes, during this time, is the MOST important thing. This is the easy part. Pit Bulls LOVE people, and are happy to be around them at any age, especially when they have been taught from early on that people equal "good stuff" like treats, belly rubs and toys. Socialization with other dogs is essential, but can be more tricky given the dog-aggressive nature of the breed. If your pup's not around them and learning to behave in the presence of other canines at an early age, you could find yourself with an adult that goes nuts at the mere sight of another dog from 4 blocks away. Socializing your pup with other dogs should be done in a strategic, purposeful way--it's not about taking your pup to the dog park and just letting him run loose!
Take your pup to places where he can have positive, controlled encounters with new people and other animals. Visit your vet's office, even if you don't have an appointment. Take him "shopping" at the pet store. Go to the local strip mall. Take your dog to parks where you know other dogs are generally kept on leash. Are there any dog-friendly stores in your area? Pay them a visit. Matches (practice dog shows) are also a great way to socialize.
Puppy k is a good way to get your pup around new people and especially dogs in a controlled, monitored setting. Take your pup through a course once, maybe even twice, and as young as the school will let you (usually 8 weeks--up until 6 months of age). You should be aware, however, that even pups as young as 8 weeks old can be aggressive towards other dogs. Schools that utilize off-leash play sessions should be avoided, especially if your pup is older than 12 weeks. Instead, find a school that allows pups to socialize casually ON leash, while owners (and most importantly a saavy instructor) are close by to help stop any problems before they can start. It is important that you work to help stave off any overt adult dog-aggression by only setting your pup up to SUCCEEED and be in situations where he has opportunities to be rewarded constantly for GOOD, non-aggressive behavior. Aggression is part genetic, and part learned behavior. If your pup learns that he can bully other dogs and play rough early on in life, the behavior could escalate into full blown dog-aggression by the time he's an adult.
It's important during these early stages that your pup has only positive encounters. You don't want him to think that meetings with new people or dogs will result in scary or hurtful outcomes. Keep a bunch of your pup's favorite treats on hand whenever you head out socializing. Reward for good, calm behavior. Attention on you should ALWAYS be rewarded. Sitting politely for pets and attention also deserves a reward. A loose leash (don't tug at your pup!) and keeping yourself calm and relaxed (slow and deep breaths ) are essential. Don't FORCE your pup to meet anyone or investigate anything. Let him act of his own accord, when he feels ready. Encourage him, and praise, but never force, bribe or coddle.
Socializing with other dogs.......
Calm, polite behavior around other dogs deserves a reward. If your pup gets pushy or too rowdy, distract him and get him back under control (ask for a sit--you should have been practicing this!), and when he behaves, reward him by allowing him to again approach the other dog. It is important to only have your pup around other dogs that are non-aggressive and generally well behaved. An early bad encounter with another dog could cause your pup to develope fear aggression. It is also important to avoid physical corrections when your pup misbehaves around other animals. Instead of associating the corrections with the bad behavior, the pup could associate them with the other animal--this can cause fear, frustration, and agitation, all of which could easily develop into animal-aggression. Instead, set your pup up to succeed by being careful how you socialize, and who you socialize with. If you do find yourself in a sticky situation, distract your pup, or retreat if necessary until you have the pup under control. Then try again under less distracting or stressful circumstances.
The key to socializing your Pit Bull pup with other dogs is to prevent him from engaging in bad behavior in the first place. Even rough, unruly play with other dogs can later develop into aggression and fighting behavior. This is why it is important to prevent bad behavior and reward good, calm, collected behavior.
What about socializing older Pit Bulls around other dogs? The optimum time for socialization ends at approx. 12 weeks. However, socialization should continue throughout the dog's life. But doing so with a Pit Bull over six months of age can be more risky, especially if you do not know the dog's background, and training & socialization history. Caution is always necessary, and keeping your dog on leash is a must.
Introducing your older Pit Bull to another dog should be done on nuetral territory. An open area, like a park field is a good place. Take the dogs for a walk together (each one on leash and held by a different person). Let them gradually adjust to each other's presence during the walk while keeping them at a safe distance.
It's up to you to "feel" your dog out -- how reactive is he to the presence of other dogs? Is he squirmy, waggy with a lower-set fast wagging tail, or play bowing? He may be interested in a playful greeting. How about turning to the side, licking the air, or yawning? These could be signs of nervousness or stress, but a willingness to avoid conflict--your dog should be rewarded for such gestures, and not pushed to greet other dogs. Lungy behavior, high-set wagging tail, stiff body language, and staring can seem like non-aggressive behavior, but these can be signs of a dog's desire or preparedness to engage in fighting behavior. If your dog is behaving in such a way, avoid running him right up to another dog. Instead, keep him at a distance, practice some obedience exercises with him, and gradually acclimate him to the presence of the other dog. If your dog seems indifferent, don't force him to say hello. Pit Bulls prefer the company of their humans, anyway. The main goal of socialization is to help your Pit Bull learn to behave around other dogs, not to teach him to "like" them. And remember, no matter how well behaved a Pit Bull seems, ALWAYS keep him on leash--off lead play sessions (such as in a dog park) are a big NO-NO!
Very wild, unmanageable dogs may require desensitization and counter-conditioning. Instead of trying to socialize such dogs on your own, contact a behaviorist who can teach you how to teach your dog to behave around other animals.
Remember, there are some dogs that are NEVER going to be "good" with others. The best you can do with such dogs is teach them to control their impulses and help them learn "replacement" behaviors like sitting calmly, and ignoring the presence of other dogs.