The cruciate ligaments are a set of ligaments arranged in an X used to stabilize a joint while providing a wide range of motion. In my short 8 weeks at the hospital, there have been at least 3 cruciate repair surgeries. The ligament occurs in the stifle (analogous to the human knee), the foot, neck and fingers. In animals, the rupture/damage of this ligament is relatively common with age being a major factor. There is an anterior cruciate ligament and a posterior cruciate ligament that cross over one another.
The cranial or anterior cruciate ligament (like the human ACL) is often damaged. In terms of recovery, normal function of the limb is usually regained in 12 weeks.
The following is a video of a veterinarian explaining the symptoms and diagnosis of cruciate injuries in dogs: