Thanks to the above people for posting their experiences. I can only imagine how heart-breaking it must have been for you. Retrievers are a fantastic breed, and if I were getting another dog, that's probably what I'd go for, given the choice. But once a dog is in the family, it's like one of your kids, and if one of your kids had health problems, you wouldn't send them back where they came from!
Good luck with finding one Tina - don't be put off - I know Adelaidenow's dog and she is the most gorgeous, gentle, lovely dog, even with her problems, which as he said, are completely controlled with medication.
Have you tried ringing up the local vets to ask if they know of any puppies coming up?