I was thinking the same thing about separating them for a small amount of time as well. And yes they both are offered hay,sweet potato,corn,carrots,dandelion greens,oats and pd puppy pellets so their diet is complete. My vet on Long Island is the most reliable vet I know of from the circle of pd owners from here. I have had pd's and have been using the same vet for the past 8 years. The problem is there is just so little info on these guys and limited testing that sometimes there is no easy explanation. Maybe she is just a runt. There was another runt in the litter that she was in although that one is a bit bigger and doesn't have the extreme hair loss. What I neglected to mention earlier was both my pd and the other runt had a bout of edema at the end of May that lasted on and off through June. Tests were run on both and nothing came up. We, meaning the vet,myself and the other pd owner were chalking it up to a very bad allergy season in the North East and they had some sort of reaction to it.