
One of my pups from our litter in the summer had a hernia, she was checked over by my vet again at 8 weeks who said it was closed and as a matter of routine should be fixed when she was spayed. We told her new owners about it they were happy, they took her to their own vet who said he agreed with what my vet had said and that it shouldn't cause any problems.
Unfortunately it didn't work like that, just a couple of weeks ago (pups are now 5 months old) the hernia was the size of a golf ball, they rushed the pup to the vet, who was operated on immediately, she had part of the bowel pushing through the hernia, thankfully the bowel was only bruised and because of their quick action, didn't need any removing as it would heal naturally. She was also spayed at the same time and is now fighting fit.
When she was new born we were told to keep pushing the hernia in as this 'might' help, but it didn't and when it closed and sealed we all thought that was the end of it until her spaying.
Obviously you have to declare this on the puppy insurance before they leave so it won't be covered, but most dogs go on to live full and healthy lives with hernias, I had a CKCS many years ago that had one which never needed any treatment.
Thanks for the link Brainless, makes interesting reading.