Hello,
Well, no dragon will ever replace Pumpkin, that is for sure. You will see him again I am quite sure of it. He will always be with you.
Maybe he had a tumor of some sort if she felt something was blocking him, & he was having trouble breathing. However, their breathing becomes erratic when they decline. More tests would need to have been done to determine the cause of death. I am sorry you don't have closure, that makes it harder.
Tracie