We did loose this bucks grand sire to what may have been heart failure. So it's possible that is what was showing up early.Not always. We had a Doe develop some of the symptoms of pasturella, but not all, nothing else fit what she was dealing with. Ended up she had congestive heart failure and died two years later. Never got pneumonia, always ate and drank, but was a bit lethargic. Even raised three large litters.
Did you check the Bucks organs?
If that is the case he needed to be culled.
I am disapointed though he was a very nice buck.
I didn't check too closely on his organs, I probably should have. Mostly I just held him up to my ear while he was still alive and didn't put him back in his cage after I heard the rattles. Could have been his heart or his lungs. There was no discharge though. Which could be a good indicator it was his heart.