Could be a torn or sprain tendon and an orthopedic specialist would be necessary to determine that, more than likely. If it's completely torn and retracted from the bone, it will become very disabling and even partial tears of the CCL and so forth become nightmares at times. I'd crate rest your little one when you can't watch him and keep the dog from all jumping or play until the specialist's examination. Dogs are stoic by heredity and programmed not to show pain for fear of showing weakness which can lead to attack and death by another predator and with most dogs, no amount of domestication has re-programmed this tendency to mask pain.
__________________  Jeanie and Tibbe One must do the best one can. You may get some marks for a very imperfect answer: you will certainly get none for leaving the question alone. C. S. Lewis |