Thank you so much to everyone for their input and advice. I have contacted several trainers but most of them, sadly, use corrections and negative punishment to train the dog. I have been working with CJ and he's very smart and obedient for me. I do think, however, that Melanie is correct and his biting is a result of fear rather than aggression. He can be very skittish sometimes. When he has to stay at the vet for any length of time, the vet will give him a mild tranquilizer and muzzle him if necessary and that seems to keep him calmer. Does anyone have any advice on muzzling a dog? He doesn't seem to be in any discomfort when he has the muzzle on at the vet's office.
Once again, thank you so much for all your input. I certainly have a great deal of imformation to think about.
Doris