has anybody got information on this condition, ie, when would it become obvious, how long would a pup last with this condition and anymore useful information would be appreciated

It would last a matter of days at most - certainly less than a week before it was obvious it was seriously ill.

This condition presents in two different ways: the obvious one is where there is no anal opening at all, and is apparent at a basic examination; and a more subtle kind (known as 'occult') where the apparently normal anus leads to a blind cavity within the body, unconnected to the intestine. This is best diagnosed by a vet.

My freinds daughter was born with this condition and it needed a host of operations and a lot of luck to give full functiuon.  she is now in ehr twenty's and perfectly normal, though does require medication to ensure she is never constipated.

So in practical terms for a puppy there is only one outcome, for it to be put to sleep.