I know kidney failure in humans is from poisoning the kidney's. Usually caused from alcohol abuse or eating non healthy foods, other things as well. But what I'm trying to say is, I wonder if a frog can get kidney failure from eating non healthy foods. Or it can come from inbreeding of frogs. When I was breeding fish, you would have to cross new blood into the line, but in order to keep what you ready worked on for so long. You would breed the father to the daughter and then the father to the grand daughter. Also do the same with the female. Then eventually take the one of the babies of the 6 spawn and breed it with the female side. Then start the process all over again. I don't know if this works with reptiles, but I know if you keep inbreeding with any animal, your just going end up with sick animals. Also most people who breed animals are in it for the profit and don't really care if the one you buy is sick or not. So it could be a lot of thing's for causing the kidney failure to happen.