I remember long before training collars were readily available and only experimental and very pricey, I had a young beagle which was a cross between a basset hound and a beagle, which we got when we were just kids. As we grew older we hunted rabbits and pheasants behind that dog all season long. He was good at it and we did lots of it.
Anyway, we decided to take him north for a hunt in mid Michigan, and try him on snowshoe rabbits. We started off Saturday morning for about 15 minutes and the dog lit out balling and bellering cross country. He found out that there were some REALLY big rabbits with long tails in this country and off he went to chase them. He traveled across a whole several miles til we could finally catch up to him. Needless to say we were not happy with his decided preference for these long legged animals that grow antlers in the fall.
Not knowing grass from corn stalks, I asked my uncle what I should do about it. He said, "every time he sticks his head in a track" whack him!
It was pretty funny after the first few nosings of those bad tracks. He would stick his nose in, and then wince because he knew what was coming. And by golly it worked like a charm....after the first day of nose in track and whack..whack, whack....he got the message and never looked at one again.
He was a great dog, and though technically he was my younger brothers dog, we covered a lot of ground with him and my memories of him are some of the best ever.
All dogs are trainable, if you have the time to train them. The collar works extremely well for this type of training and can curb a bad habit better than anything else going.