A ruptured cranial cruciate ligament is the most common orthopedic injury of large breed dogs, but can occur in any dog or cat.  It causes lameness of one of the hind legs, due to a tear of one of the stabilizing ligaments in the stifle (knee).  Frequently there is also damage to the meniscus which is the "shock absorber" of the stifle joint, thereby causing more pain.  This condition usually occurs when the pet is running and makes a sudden turn, but the leg gets caught in a hole or other obstruction. 

Surgery is the recommended treatment as discussed in the attached article.  The surgery can be done by a surgical specialist or by Dr. Johnson at the Birdneck Animal Hospital.  The advantage of the surgical specialist is that they do the procedure more often.  The advantage of having the surgery done at our veterinary clinic is substantially lower cost with still a very high probability of a successful surgical outcome. 

Words from a veterinary orthopedic surgeon.