Hello Esther,
That is too bad Buddy has had trouble with metabolic bone disease. Yes, unfortunately, it can & will do irreversible damage to the bones, but at least you have halted the damage.
i am happy to hear he can get around pretty well most of the times then, that is important.
As far as I know, there are no direct links of diseases solely from metabolic bone disease. He may develop arthritis when he gets a little older. He may also have some trouble absorbing his calcium when he gets a little older, prompting the need to switch from powdered calcium to liquid calcium to help him out.
It sounds like he is doing much better now thanks to your vet, that is great news!
Tracie