I do not agree, I believe all dogs can be trained, you need to be Alpha at all times, and they will be submissive and you can train them. Failing being Alpha (and knowing the appropriate ways to do so) you cannot solve the issue.
Very dangerous to do if you are not trained. The vast majority of dog owners are not alpha..hence their issues, especially if their dog is the alpha in the pack. I have an alpha golden. Unfortunetly for him, I am more alpha!!
But a dog or any pet is family, you do not just pass one family member off for another one.
It's a dog, not grammie!! A dog. And that's the problem with dogs and their behaviour nowadays....people think of them as family.
Springers are typically high-energy dogs. One that isn't being exercised enough can be bored, irritable and aggressive. (Note, I haven't read this whole thread. I do not know how much, how often or the quality of exercise this dog is receiving.)
However, I have had to re-home a lab that was an expert fence-climber. She wasn't safe anymore. I re-homed her to my BIL, who lived in an apartment and was a bachelor. She lived to a ripe old age and he took her frequently to the park to play ball. She died a happy, loved dog.
I have also adopted a re-homed Cocker. He is not aggressive, but he is sensitive to people picking him up. He will growl and "air-snap". This doesn't bother me, since I can identify the problem and take steps to correct it. He also digs in the trash and jumps up on the table. We rectify these by kenneling him when we are away from home. However, his former parents didn't disclose these "features", which I'm sure where factors in his re-homing.
For the OP, we got our cocker from craigslist. I recommend craigslist or petfinder. Perhaps charge a small adoption fee. Include the pet's food, toys and supplies.
Then, I would recommend a cat in the future. Dogs are a lot of work. They must be properly socialized and trained from an early age. This must be constantly reinforced.
My dogs are never allowed to eat or receive treats without performing an obedience skill. It is constantly reinforced to them that the pack hierarchy includes all of the humans in our home above them. Our children feed them and the dogs must sit and wait until the bowl is placed down and they are "released" to eat.
At the very least, I would not add another dog to the home until the youngest child is at least 6. Then I would do a lot of research into family-friendly breeds and proper training.
I was hoping there was a kindred soul here!!!
To the OP....I'm so sorry you are having this issue. Springers are terrific dogs. They need exercise and discipline...lots of it. I would imagine that it wouldn't take long to reschool your dog in the correct and expected behaviours. Once you and dh learned the proper techniques, you could do corrections yourselves.
Of course you are concerned about your children. Sure you love your dog and want the best life for it, but if you are nervous about the dog's behaviour around the family then life is going to be pretty miserable.
And you're right...not many shelters will take an agressive dog. But, I don't truly think he's being 'aggressive'..I think he is choosing bad ways to communicate with you. If he has gotten a clean bill of health from the vet, I would find a trainer who will come to your house...maybe for an hour or so for a few weeks. One on one, in the home is really the best way to go. At the moment, your dog has all the power, and he knows it. Springers are smart...they get it. We have a friend who has a springer. Man, that dog is badly behaved. Why? Because he is allowed to be. When he is at our house (we dog sit him fairly frequently) he toes the line. In fact, when his owner come to get him, they always remark how good he is for 'auntie di'....sure he is, he knows the expectations at our house. But, once his family is there...it's all gone up in smoke. They just roll their eyes and say...'Oh, he's so naughty.' Nope...not naughty at all..he can just get away with it with his owners.
So....best of luck. Try to get a trainer to come to the house and give you some recommendations. I would call a few shelters or breeders to see who they would recommend. I know how awful you must be feeling right now. I have a 9 y/o dog as well...but he's a mush. But, he is ridiculously strong willed and stubborn. He would try to get away with murder if he could...but I'm the boss. I hand out the food...makes me the boss, not him. And he works for that food..each and every meal.
If you find you can't retrain him or can't find a new home for him, then you have only so many options. You may have to give him up to a shelter, which will in turn have to put him down...no kill shelters charge a hefty sum. Or you can keep him at home, but behind gates. The one thing I will suggest for keeping him off the furniture is this....get some of that really thick plastic floor runner...the kind you would put over your carpet in the winter to keep it clean. It will have little prickers on the underside to keep it from moving around on the carpet. Cut sizes to match your furntiure, then put a piece on the furniture but flip the plastic upside down. The animals don't like those little prickers one little bit..hurts their paws. Pretty soon he'll stay off the couch. Just remember to remove it before you sit down!!!!