What to do?

Question
We have a 2 year old cocker spaniel.  I don't know what to do. We bought him from a breeder at 8 weeks old.  When brining him home he was shaking and could not sit still. Had him around people kids, etc.  At 12 weeks took him to obedience training where he hid under things or behind me.  At 9 months old he changed.  He lunged at a neighbor boy.  He had been around this and other children so it took us by suprise.  We have had Behaviorists work with him, at our home, and have taken him to the University Behavorist.  The Univ. of MN Vet put him on prozac and there really was no change.  He is just unpredictable.  We have done music, changing the door bell, clickers, etc.  He is going to Dog Daycare for the last year, 3 times a week, so he associates with other dogs.  He will play nice one day and then bite at larger or smaller dogs.  He is a smart dog.  He can open doors with a handle.  We have the gentle leader on him and he still growls, barks, and snarls at people whether they are coming into our home, the daycare or on a walk.  We have not had our sons (twins 8 yr. old boys) because of this.  Lately we have had boys over and I just keep him on a tight leash right with me.  Some of the boys he acts indifferent to and others he lashes out.  When he was 8-9 months old and some one would come to the door, his eyes would get red, buldging and I could swear he was going to foam at the mouth.  The bid problem is our son.  He always wanted a dog and named him.  But somedays Shadow is so loveable and then another time, same exact situtaion, he growls and shows his teeth.  We have read about rage syndrome and can see some of the characeristics in Shadow.  The breeder says we should put him down, that his mind if "on fire" with these rages and is really an unhappy dog.  Is there such a thing?  What does this feel like to Shadow?  Is he unhappy?  Would it then be putting him out of his misery?  I am at home so I am with Shadow more.  It is killing me about what to do and how to explain it to my son.  Our son was just diagnosed with Autism so he has had a rough time this year.  I was searching the internet for whatever I can find and saw your name.  Maybe you have some insight as to how this feels to Shadow.  thanks

Answer
Your breeder may be right, but if you want to take one more step, have the dog evaluated by the vet for a seizure disorder.  If the breeder is reputable, he/she should take the pup back and bear the expense of the euthanasia and provide a new pup for your son.  I can't diagnose this from afar, so if it is behavioral, and you were not able to change things with a carefully constructed protocol that you followed to the letter, than maybe you need to decide whether this dog is too much of a liability for your family.  I can't answer how the dog feels, but it seems to me that if he has lived a life where he is basically terrified of everything, or he is suffering from rage syndrome, life is not as pleasant as it should be for a well loved dog.  I will say one thing, though - I have not found it unusual for a generally fearful dog not to be able to deal with an autistic child.  Sometimes the dogs know what it takes us months or years to find out...  If you get another dog, my advice would be to get an older dog that you can test with your son to determine if the dog CAN tolerate it.  Your SPCA may have a behaviorist who tests dogs with these situations before adoption - ask!