Cranial cruciate ligament (CCL) disease most commonly affects large dogs, followed by small dogs and sometimes cats. Though the tear is similar to a human ACL tear, human tears typically result due to injury – not chronic degeneration.
The cruciate ligaments form a fibrous cross in a dog or cat’s stifle (like a person’s knee joint), which connects the femur (upper leg bone) to the tibia (lower leg bone). Pets with CCL disease experience chronic degeneration of the ligament, leading to an eventual tear. The veterinary community does not fully understand the cause, but CCL disease is thought to be genetic, as the conformation of bones stress ligaments.
Pets experiencing a tear due to CCL disease display an acute onset of lameness in one leg, having difficulty walking or putting any weight on the affected joint. CCL disease usually affects one leg, but another tear of the other leg can happen within six to twelve months.