Painful Ligament Tear in Dogs
An injury to the anterior cruciate ligament (ACL) can be a debilitating musculoskeletal injury seen most often in dogs. Non-contact tears and ruptures are the most common causes of ACL injury.
ACL injuries occur when a dog rapidly decelerates, followed by a sharp or sudden change in direction (cutting). ACL failure has been linked to heavy or stiff-legged landing; as well as twisting or turning the knee while landing, especially when the knee is in the valgus (knock-knee) position.
Dogs that are exposed to rigorous physical training and exercise are significantly more prone to ACL injuries than pet dogs and resting ones. This difference has been attributed to the discrepancies in anatomy, general muscular strength, reaction time of muscle contraction and coordination and training techniques between these groups. A recent study suggests hormone-induced changes in muscle tension associated with reproductive cycles may also be an important factor (Lean, 2005). Bitches (adult female dogs) have a relatively wider pelvis, requiring the femur to angle toward the knees. The majority of ACL injuries occur in athletic dogs landing flat on their heels.
The pivot-shift test, anterior drawer test and the Lachman test are used during the clinical examination of suspected ACL injury. The ACL can also be visualized using a magnetic resonance imaging scan (MRI scan).
Symptoms of an ACL injury include hearing a sudden popping sound, swelling, and instability of the knee. Pain is also a major symptom in an ACL injury and can range from moderate to severe. Continued strenuous activity on a knee with an ACL injury can have devastating consequences, resulting in massive cartilage damage, leading to an increased risk of developing osteoarthritis later in life of dog.
The ACL primarily serves to stabilize the knee in an extended position and when surrounding muscles are relaxed; so if the muscles are strong, many dogs can function without it. Fluids will also build the muscle. Conservative management of the affected dog including physical therapy and using a knee brace can also be tried. Surgical intervention is of utmost necessity in acute cases.
Research has shown that the incidence of non-contact ACL injury can be reduced anywhere from 20% to 80% by engaging the dog in regular neuromuscular training that is designed to enhance proprioception, proper movement patterns, balance and muscle strength (Patrick and Dick, 2003).
- McLean SG, Huang X and van den Bogert AJ (2005). Association between lower extremity posture at contact and peak knee valgus moment during sidestepping: implications for ACL injury. Clin Biomech (Bristol, Avon) 20 (8): 863–70.
- Patrick and Dick (2003). Specific exercises may be key to preventing ACL injuries. USA Today.