
Over the last 30 years I have had 15 litters, both BMD and GSD. I would say if you get a good tie whith the bitches wholhearted co-operation the chances are about 8 -2 in favour of a litter and then a 99% chance of that litter being a viable one. That is going on my own numbers, and some rounded up maths !!
Don't forget though the possible mortality rate after birth, over the years I have lost 3 pups after the first day. One the mother rejected ( Would not let it feed and it was weak and died the day after it was born) one had a deformed leg and was PTS and one was squashed right under my nose when Mum leapt into the box before I could grab her and stood on the pup. That was a particulary stressy GSD who never had another litter. I have only had 2 born that we could not get started.
That is from my very unreliable memory! ;-)
Aileen