Hyacinth, If we desexed our kids at 12 weeks we would not have the population issues we have?
Yes CL is ACL. According to Chris Zinc, the effect of early desexing is a lengthening of the bones in the legs which changes the normal angels and deflections on the joints. This means the ligaments are at angles that are no longer conducive to the types of physical activity they were designed for, and are more prone to damage.
It does not mean they will rupture, just that they are at a higher risk of doing so, and it does depend on the amount of work you do with the dog.
Dogs who do heavy work loads and who were not desexed early can also rupture their cruciates. My now departed red border, Flame, who had 2 litters before being desexed, lived for agility, competed in as many events, with multiple runs as we could get to. She ruptured her cruciate chasing a tennis ball on flat ground.
Border River Pet Resort