[sweetlee]

First question, has your dog been to obedience class?
That is a good place to start and at 8 months it certainly overdue.
The dog needs to learn "leave it" so he isn't going after every little thing that comes his way.
I found that using a pinch collar on Dodge at first, BEFORE I even took him to classes was like having power steering. But I had used these before for proofing some other dogs.
they are a training device, not a way of life.
And you must fit them right or they will not do you any good, and may even be harmful, so if you aren't in classes, get enrolled ASAP. You may not even need any training devices after that, but if you do, the instructor should be able to recommend one and show you how to properly use it.
Take tasty treats with you on walks, keep them close to the dog's nose, if he takes off after something, tell him "leave it" and as soon as he looks away from the item and at you, treat and praise him.
Leave it is a very important command, and should be one of the first learned in a good obedience class.
I can't recommend training highly enough. Actually it's not an option with a big strong dog, it's mandatory that you have total control at all times.

sharon