Any idea on how to keep my Lab, 1 yr old, from chasing my neighbors cows?  He likes to harass those in the pen also. 

I have had him on the chain for the past week.  Let him loose for a walk to day around the pond,about 15 cold min.  He came the 3 times I called him and I praised/petted him for coming.  I can mess with him now, but come spring things will be a bit to busy.  He also will follow the car or pickup off the place and run beside us for 1/8 of a mile or so.  Some times he will run the full 1 1/2 mile from the house to the farm shop where I work.  I don't like the idea of a dog living on a chain, but ....   Oh, we bought a shock collar, thinking when he was bad he would get a shock.  Wrong,  he would just leave us and find refuge at the neighbors and chase their cows.  It is more fun over there isn't Mr. dog.  Life.