Ann, try not to believe the statistics on lifespan. It's about the same for canine diabetes and Lady is in her seventh year with that!
I absolutely believe the care, nutrition, etc. they receive has everything to do with longevity. With the kind of care Wylie's gets, I'm sure he'll beat the statistics, too.
Is this type of Cushings reversible? Lady was diagnosed with iatrogenic Cushings a couple of years from taking steriods for her arthritis. She was given about six months to live. I stopped the steriods and it was reversed.