In rec.pets.dogs.breeds James wrote:
There's no way to tell whether your particular dog will get better or
worse with maturity. If you locked her up in a room for 5 years, and
then brought her back to the dog park, she'd probably be worse. But
as
long as you continue to socialize her, and stop her when she becomes
over aggressive with other dogs, she'll get better.

Not necessarily. Dog parks are not at all natural environments for dogs.
It is not in the basic nature of a dog to freely accept strangers. With
some breeds, notably Labrador Retrievers, we have bred out a great deal
of the suspicion and natural strange dog aggression. With Pitbulls dog
aggression has been bred in. Not all Pitbulls have it to the same level.
Most can be trained to obey instructions not to engage. Many can never
be socialized into playing nicely with strange dogs as adults. So the
degree to which socialization can help will depend a lot on the
individual dog. The majority of adult dogs have no business being in a
dog park. Yes, there are many adult dogs that do OK playing with
strangers, but not most dogs. Puppies tend to do well, and plenty of
older dogs that do well. But most dogs between 18 months and 7 years
will not easily accept close interactions with other stranger adult dogs.

I adopted a
5-month
old pit/lab mix, and for the first few weeks, he was EXTREMELY vocal
when
playing with other dogs, and he was relentless in the way he would
play with them (biting the neck/ear area, like dogs are prone to do,
but he wouldn't stop). When it looked like he had crossed the line
between playing and being over aggressive, I would remove him and make
him sit for a few mins. He's almost 7 months old now, and does not
growl anymore when playing. He will also roll onto his back to play
just as often as he is the one standing over another dog. He's by no
means perfect, but he's slowly making progress.

Be very careful. If you corrected him for growling you may have created a
dog that will become aggressive without vocal warning. Suppressing the
display of aggression is a very common error. Your dog has another year
to go before he becomes mature enough to display his adult temperament.
Given your description chances are fairly high that you will have a dog
aggressive dog. The best situation for your dog will be (a) playing with
carefully introduced dogs, no sudden intrusions by new comers (b)
controlled situations so that your dog sees that YOU are in control and
he never needs to display aggression, AND never needs to be concerned
about a pushy other dog.

If you can train your dog with hand signals, or fear, or whatever to
not attack other dogs, that's great. But I'd prefer for my dog just
to be comfortable around other dogs...I feel like then there's less of
a risk that he'll snap. And the only way to accomplish that is
socialization.

This is true. But "socialization" is not the equivalent of "playing
with." Socialization is the process of exposing the being to various
situations. At the moment there is probably nothing wrong with your puppy
playing with other dogs. You will, however, need to be vigilant to see
that you interupt/distract situations in which any dog becomes a bully.
Your primary reaction should not be to punish your dog but merely to call
him out of the situation and leave it. Not temporarily, but for at least
an hour, your dog and any other who engaged in teasing/testing should be
prevented from engaging in any way - even body signals from a distance.
Keep in mind that play is practice for adulthood. Through play the dogs
are learning what hurts and what doesn't, what works and what doesn't.
This has both important benefits and important drawbacks. The critical
point to remember is that you cannot socialize away natural dog-dog
aggression. You can moderate it somewhat, you can reduce its intensity,
somewhat, but neither socialization nor training will change the basic
nature of your dog.

Diane Blackman