Similar to the ACL in humans, the cranial cruciate ligament (CrCL) in dogs helps stabilize the knee (stifle) joint, the middle joint in the dog’s back leg.
In humans, an ACL tear is usually the result of a sports injury but in dogs the CrCL tear is the result of a degenerative process which doesn’t allow the ligament the ability to heal itself. Because of this, partial tearing is common in dogs and is likely to progress to a full tear. Approximately 50% of dogs that tear their CrCL in one knee is likely to tear the ligament in the other knee within the year. The breed, structure, age and weight can also play a factor.
Dogs with a cranial cruciate ligament rupture may exhibit signs of lameness (or limping), muscle mass loss, difficulty jumping or rising, swelling on the inside of the knee and discomfort.