The average age for injured puppy is between 9-13 months. For most owners the story is always the same, owners don't understand what happened, ". . . he's been doing (this) for months, and then all of a sudden, BANG, he came back on three legs"! Truth is, the puppy was injured because he had been exercising at levels that are only safe for mature dogs (hiking for an hour or longer / running at full tilt after Chuck-It balls or beside a bike...).
How this happened should be no mystery. The diagram illustrates all the asymmetrical development of puppy's limbs. The hips, shoulders, elbows, stifles, hocks and SPINE are all vulnerable, creating more serious risks than when the puppy was young.
Please limit the amount of exercise for your puppy (refer to my exercise guidelines).