2007 AKC CHF ANNUAL CONFERENCE
IS CANINE DEGENERATIE CRUCIATE RUPTURE A CONSEQUENCE OF RHEUMATIC DISEASE?
Dr. Peter Muir, University of Wisconsin-Madison
Rupture of the cranial cruciate ligament (CCL, also known as the anterior cranial cruciate, ACL) is one of the most important orthopedic conditions of dogs. Americans spend a huge amount of money annually on this condition.
Clinical features: The dog usually has low-grade lameness for several months, which precedes stifle instability and more pronounced lameness. Owners may think it happened all of a sudden. But at surgery not only is the ligament ruptured, but the joint has arthritic changes that suggest a condition of long standing-even when the surgery is done immediately. These results suggest that the rupture is a consequence of a pre-existing arthritic condition that only results in rupture when it reaches a certain point. In fact, stifle arthritis is present before rupture. And once one stifle goes, the other usually follows. That's because it already has the same arthritic changes.
More evidence: Arthritic changes cause a stifle synovitis, in which the synovial layer is inflamed. The ligament derives most of its nutrition from the synovium adjacent to it, and experimental studies in which stifle synovitis was induced resulted in the tensile strength of the CCL ligament to be reduced to 29% of controls after 6 weeks. When these ligaments ruptured, they did so mid length, as is seen in clinical cases. When the control ligaments were made to rupture, they did so where they were attached to the bone.
What causes this stifle arthritis? It may be a form of autoimmune disease. But at present, it's unknown. Future research will be aimed at identifying susceptible dogs, by genotype if possible, and determining if treatment with antibiotics or anti-inflammatory drugs early on can prevent rupture.
Rupture of the cranial cruciate ligament (CCL, also known as the anterior cranial cruciate, ACL) is one of the most important orthopedic conditions of dogs. Americans spend a huge amount of money annually on this condition.
Clinical features: The dog usually has low-grade lameness for several months, which precedes stifle instability and more pronounced lameness. Owners may think it happened all of a sudden. But at surgery not only is the ligament ruptured, but the joint has arthritic changes that suggest a condition of long standing-even when the surgery is done immediately. These results suggest that the rupture is a consequence of a pre-existing arthritic condition that only results in rupture when it reaches a certain point. In fact, stifle arthritis is present before rupture. And once one stifle goes, the other usually follows. That's because it already has the same arthritic changes.
More evidence: Arthritic changes cause a stifle synovitis, in which the synovial layer is inflamed. The ligament derives most of its nutrition from the synovium adjacent to it, and experimental studies in which stifle synovitis was induced resulted in the tensile strength of the CCL ligament to be reduced to 29% of controls after 6 weeks. When these ligaments ruptured, they did so mid length, as is seen in clinical cases. When the control ligaments were made to rupture, they did so where they were attached to the bone.
What causes this stifle arthritis? It may be a form of autoimmune disease. But at present, it's unknown. Future research will be aimed at identifying susceptible dogs, by genotype if possible, and determining if treatment with antibiotics or anti-inflammatory drugs early on can prevent rupture.