What could cause dog to limp?

By Dr. John Koch

Question: I have a 4-year-old mixed breed dog that is mid-sized. About one week ago, we were playing fetch when he suddenly let out a painful cry and has been limping on one back leg ever since. Could he have hip dysplasia?

Answer: Only an examination can determine exactly what is causing your dog to limp. Hip dysplasia usually does not have the acute onset you describe. A more likely diagnosis is a torn cranial cruciate ligament. Cruciate ligament injury is by far the most common reason for acute lameness in the dog. This injury accounts for about 20 percent of such problems.

The function of the ligament is to prevent the tibia, which is the lower bone of the stifle or knee joint, from slipping forward when weight is placed on the rear foot. When slippage occurs, pain is felt and the dog responds by limping. Over the years, a number of surgical techniques have been devised to replace the ligament or its function. Although a number of these techniques have improved the stability of the joint, none have proven satisfactory in restoring the joint to its original state. An improvement of approximately 80 to 85 percent is considered very successful with these older procedures.

Several years ago Dr. Barclay Slocum, a veterinary orthopedic surgeon, departed from traditional surgical thinking regarding these injuries. He noticed that the slope of the top of the tibia in most dogs averaged between 20 and 30 degrees when measured against the long axis of the bone. This slope causes the tibia to slide forward when the cranial cruciate is torn. Dr. Slocum discovered that when this slope is changed to 5 or 6 degrees, the tibia no longer slides when weight is placed on the leg. The surgical procedure he devised to change this angle is now considered the gold standard for correcting the mechanical problems caused by cranial cruciate injuries.

This surgical procedure is called a Tibia Plane Leveling Ostectomy. The equipment and training required to perform this technical operation limit its availability. Across the nation, the average cost of the procedure is between $1,200 and $2,500. However, results in dogs having had the procedure eight years or more ago have been judged to be excellent and far superior to the older techniques. Although complications are possible with any surgical procedure, the vast majority of orthopedic surgeons recommend the TPLO procedure for patients suffering from cranial cruciate injury.

Dr. Koch is a Cape Girardeau area veterinarian.