I've just met our lovely trainer in town who is well versed in the training and behaviour of pet dogs. She advised us to see a specialist working dog trainer for our pup who she feared may bite someone. I have been reading up a bit about working dogs and their needs. With another of our dogs, several years ago, it really came to light that a pet dog trainer/behaviourist (all APDT etc) wasn't going to cut it and luckily, while I was tearing my hair out and pulling out my eyelashes in despair, I found a breed specific trainer.
It's all a steep learning curve and interesting to find that working dogs are not bred as pets, or neccesarily for temperament, and have drives and instincts that have been bred out of showing/pet dog lines.
So... We have all worky work dogs, a goof, a nervous wreck and a snapdragon. Well, well, well.... I always thought collies were mad. They're not. But they are special.