Rhinestone, we were invited to a christening. We were gone for three days. A close "friend" was being paid to housesit and care for our dogs, one of whom was in heat. This "friend" decided that it was:
a) Perfectly fine to have them all in one room together (despite the fact that we had told them under no circumstances to do so, as the male was too young to be neutered but old enough to do the deed, and one of the females was not yet spayed)
b) Only natural for them to mate
c) Not neccessary to inform us of this
So it is all too possible for this to happen. Given that we had managed for every previous season to keep her away from any male dog, including our own (large, fenced garden, dog run, dog gates and close supervision, etc), we thought that all would be well. The "friend" just felt that they would make lovely puppies apparently 
Although they didn't want one, or to help with rearing them. Or to help with the vet bills - that was too much, I insisted they help pay for the emergency c-section and come and see the state our poor bitch was in because of their idiocy.
Anyhow, the vet is helping us to find him a new home, and we have had some interest from members of our extended family, so just have to get on with it now!