Thanks, I'm definitely keeping the jump height at 12" and I told my trainer to keep it at that height until she's at least a year (at which point I'm getting her PennHip'd).

In actuality, though, I've been reading up some more on HD and I got the impression that the cause is completely hereditary. Either they have it or they don't have it. Diet and exercise will only exacerbate the already existing, or about to develop, HD. With that in mind, I wonder at how much I should actually worry. If Ivy has HD, she's going to develop it no matter what I do, albeit I can control the severity of the disease. If she doesn't, however, diet and exercise alone can't cause it.

Hmm. I think I'm going to PennHip her soon to see my course of action.