I would assume that's VHD too. Tia dropped dead at Christmas with no ill health beforehand. In fact I'd just noticed she was looking in fantastic condition (I'd had her a year) so I was very shocked to find her collapsed one morning after she'd eaten her breakfast all up. The vet checked her over and said her lungs were fine and her womb felt fine (I didn't get her spayed as she was a nethie, very small and not in great health when she was rescued, so I didn't want to push it) There was just a slight drop in her body temperature, which I guess indicates shock. What caused the shock I don't know. Internal bleeding? Liver failure? Sometimes if they have been starved, fed badly, or had lots of anaesthetics and stress, their liver packs up. I couldn't afford a PM so I'll never know. E-Cuniculi also causes sudden death sometimes.