i have a 8 month old female gsd with tons of preydrive you just have to throw her the ball shell get it with in a sec i just have problem walking her. In my area there are lots of stray dogs and pigs. dono if its prey drive or aggression she wants to kill em like barks and drags me around she is a big girl 60 pounds already :S . once she got off leash and chased 3 stray dogs and brought one down to the ground but didnt bite it. i dono if she wants to play with them . if she see a stray dog or pig she just stands still like rigid body wont move they just have to move a step and she trys to bolt to get to them. im having tough problem right now i only have a flat buckle collar and a choke chain honestly i did try to use it the choke chain didnt work she is like ill die tryin type cant give correction with choke chain she will be like panting at the end of the leash. bought a prong collar from herm sprenger waiting for it to come ps she exercises 2 hours daily including obedience. non aggressive to people but wont like to be touched by a stranger. my friend left his small local sheep hearding puppy with me for few days my dog never showed aggression to the puppy she's like while playing pulls the pup backward with her legs dono if she wants to hurt . i made sure that the pup was away but the pup stayed for 5 days with us with out any problem .dono if my dog has tons of prey drive or aggression . i dont want to take her out of drive .
SORRY FOR LONG QUESTION

It doesn't really matter if it is aggression or prey, the fix is still the same: train her to ignore the distraction by looking to you for direction.

Start in a low distraction area (inside at home) and play the look at me game. Then move to a slightly higher distraction area, etc, etc, etc.

More exercise and metal stimulation (ball or tug in the yard) before you go out to the loose dog and pig area will help. You could try having her wear a weighted vest to use up more of her energy.

Puppy people....is a weighted vest safe to use with an 8 month old pup?

The general reccomendation for adding weight is two years old. I myself am so happy to finally be at 2!

You should also be careful about running her hard for a long time at this age.

It would be better for her physically to play ball for 10 or 15 minutes, take a break to do something else, and then running her again. If you do some obedience work in the break its even better.

If she has the drive and energy level the OP claims, she will get spun from chasing the ball to where she will go beyond her physical limits. Its also not good from a standpoint of teaching her to control excitement.

I only know because when my pup was this age she would get so wound up from playing that she would end up jumping like a kangaroo and biting me if OB wasn't part of the game.

And to the original question: Stay away from pigs and loose dogs if you can help it

In addition to the other advice, I'd add that it sounds like seriously concentrating on basic obedience is in order as well.

Are you familiar with marker training?

I would not be letting my dog pull a pup around by her back legs either... JMHO.

she is doing good in obedience just have the problem with dogs and pigs and she even turns on command vs people :p