Having gone through many losses, I do know your pain, and your heart is broken.It is such a shock and will always be pain that you can not forget. I hope that you get some answers. I have the feeling that maybe the wrong anesthetic was used,but perhaps he did have an undiagnosed heart problem. Whatever the answer-it won't heal the pain of your loss.It will take time,and in time the best medicine will be another pup. There is always a pup that will help fill that other part of your heart. I am so sorry for you.