A few weeks ago Jess visited us as she had taken a tumble on the staircase. She was not placing her leg on the ground and it seemed very sore. We put Jess under general anaesthetic in order to take some x-rays and palpate her injured leg. Our veterinarian discovered that Jess had ruptured her anterior cruciate ligament (similar to a footballer's knee injury).
Jess had surgery about a week later, and is now in recovery from this. Keeping her quiet post operatively seems to be the difficult task as she does love to run and jump. Fortunately her owners have confined her well, giving her leg the best chance of recovery.