not sure never had this happen, but maybe he had somethig wrong with heart and ya just didnt know it, like humans, or yes i had a friend who left her dog with friend for weekend, it came up a storm and the dog was scared of thunder , got so scared it died . only way to know is have a altopsie of him. so sorry for your lose am going through a lose to and its heart breaking. take care
I'd also suspect he had some underlying heart disease that was undiagnosed. I'm so sorry to hear of your loss.
I'm very sorry for your loss. I know it's hard, and that not much can be said to make you feel any better. However if you are looking for some closure I agree that an autopsy would be a wise thing to have done. We can suggest what we believe might have gone wrong but the only way you're ever really going to know is through an autopsy. Again I'm very sorry for your loss.
cardiomyopathy can come on sudden like that. Some Doberman bloodlines are prone to it, not sure what kind of dog yours was.
so very sorry for your loss.