This is true..my gr/yl mix had exactly the same problem..in effect..he was growing too fast for his body to keep up..it had nothing to do with hip dysplasia or anything. He's a big muscular boy..100 lbs now at 8 1/2 yrs. the vet said it's common in large boned breeds. good luck! I'm sure he'll be fine By the way, how do you like that breed????