Thanks folks-was a real shock to say the least

PM results so far show cause of death was to do with heart n lungs showing 'scarring/damage' which could mean she was born with these defects (however the vet doesn't hold such faith in this area) or that it was due to a serve respiratory type illness (vet holds strong that it is this), in which case if it was the latter then it had been there longer than a week and therefore should have been picked up by t'other vet.
There are more 'extensive investigations' going on and concrete results will be established by Tuesday at the latest-apparentlly. (sorry if anything sounds a bit jumbled, i'm just quoting exactly from the message i received.)