How can I find out if a breeder has bred other puppies with the same serious health condition?

We bought a puppy this summer, and later discovered that she had congenital kidney disease. After several trips to the vet, a bunch of tests, and a lot of stress trying to keep her as healthy as possible, we had to put her to sleep. She was clearly suffering, and we couldn't make her continue to suffer. Before we brought her home, we had done research on the breeder and found complaints about her. Unfortunately, we had already made the deposit. After talking to some happy references she had, we decided to go through with the sale anyway. How do I find out if she has bred other puppies with kidney problems before? What can we do to stop her from continuing to do so? She has already been suspended from the AKC for other reasons.