Recent research suggests that dogs can have a genetic predisposition to CCL weakening or degeneration, leading to an eventual tear. Other factors, such as developmental, anatomic, and hormonal, may also contribute to this degeneration. Tears in the CCL cause the knee joint to become unstable. This instability can also damage the menisci, or shock absorbers in the knee. Approximately 40% of dogs who tear their CCL will also have a meniscal tear. Because of the genetic predisposition to ligament degeneration, 50% of dogs that injure one CCL will go on to injure the other side.