Mumsical - Sorry you got a BFN, but you know what we say about AF showing and all. How old are your pups? Parvo can live in the soil for months so it's possible someone/dog could have brought it in the yard. Keep the other pups away from any outside areas you had them in. And keep future litters away from there too. As soon as you notice one of the other pups is a little off, take him straight in. The sooner you get them treated the better. I'm sure your vet told you all that but, being one myself, I don't think you can hear it enough. It's a nasty illness but I've seen pups pull through parvo so don't lose hope!!