It's a combination of diet and being genetically predisposed to this problem. Keeping the fluid intake up helps. Feeding at least some wet food preferably at least 50% wet. A water fountain helps with many cats because they prefer running water. For cats that have had the problem there are prescription foods that are often able to control the problem. A cat that isn't prone to it seems to able to eat any kind of food and not have any problems.
I really hope the new vet can pinpoint the problem with Pippen and that it is fixable or controllable.