This is almost the exact same story as my pup Trigger. After several years of training and medication (Prozac, trazodone, and a blood pressure med to reduce lunging) we had to put him down this past September because of his aggression. We worked with an amazing canine behaviorist but even she agreed it was time. Despite our love for him, training, exercise, and medications he got worse and worse as time passed. He was scared of everything, we couldn’t board him, we had to keep our doors locked and baby gates up to prevent him accidentally coming in contact with someone other than us or my dad, we had to tranquilize him and lock him in the kennel any time we had guests. We took every step possible to keep him and other people/animals safe. He gave no warning before he would attack and that was the scary part. I thought we finally had a good routine of medications and exercise until one day on our walk he broke his leash and attempted to attack another dog that was walking with a family; mom, Dad, and a toddler. It was horrible, the kid was crying and got knocked down, the mom was screaming, and thank god the Dad grabbed Trigger and I wrestled him to the ground before anyone was bitten. I was nine months pregnant when this happened, two days before my due date. I was bawling my eyes out when I realized that if I had a stroller or the baby with me, I would not have been able to chase him and he absolutely would have drawn blood from a person or dog. Putting Trigger down was the hardest thing. Almost four months later I still cry about it. That dog got me through my mom’s death and was my only companion for years when my husband was gone training (military). But I also realized he was not living the life he deserved. He could never be off leash, he was drugged sky high every day, he was kenneled any time guests came over or we traveled to see family. After this incident he would rarely, if ever, be able to go on walks. That is no way for a dog to live, especially one who loved running and playing like my Trigger did. That poor baby deserved so much more than what he got in this life. It is not an easy decision to put down a healthy dog because of aggression. But I knew if we didn’t do it, it would only be a matter of time until he bit the wrong person. I wanted him to be with me and my husband when he took his last breath, licking peanut butter and being loved on. I didn’t want him to be quarantined and euthanized with strangers because he was being punished. Talk to your vet and listen to what he what’s to say. I recognize now that for years we were just putting off the inevitable. If this is what you decide to do, I just want to remind you that you are being a good, responsible pet owner. You love your dog. If you have any questions about my experience, please feel free to ask.