How CCL Injuries Affect Dogs
Damage to the cranial cruciate ligament (CCL) is the most common cause of canine hind limb lameness and is a major cause of degenerative joint disease in the stifle (knee) joint of companion dogs. The cranial cruciate ligament is critical to stabilizing a dog’s stifle, which is the equivalent of the human knee. When the CCL is torn, the upper ends of the two long lower leg bones (the tibia and fibula, like the shin bone in people) become loose within the knee joint, causing abnormal friction, wear and tear. This, in turn, leads to joint swelling (effusion), stifle joint instability, pain, lameness in the affected rear legs and, ultimately, chronic irreversible degenerative joint changes. Dogs with ruptured CCLs will become lame suddenly, because of the pain associated with this injury. They may feel better after rest, but once they rise, walk around or exercise, the pain will return, as will the lameness. They will just plainly hurt.
Symptoms of CCL Injury
The outward signs of cruciate damage depend upon the severity of the injury, which can range from a partial tear to a complete rupture of the affected ligament. Without surgical correction and appropriate post-operative management, the effects of CCL injuries can progress and become permanent. Most owners of dogs with cranial cruciate ligament injuries first notice a sudden onset of lameness or limping in one or both rear legs. Most of these injuries happen when a dog is romping, roughhousing, running, playing, jumping or engaging in other enthusiastic antics. Owners often report that their dog suddenly stumbled, possibly yelped and then “came up lame.” However, the affected ligament probably experienced excessive wear and tear well before observable signs of damage became apparent.
Symptoms of this condition that owners may notice include:
- Lameness in one or both hind legs; may be non-weight-bearing; may come and go; may come on very suddenly
- Limping or reluctance to use one or both hind limbs, which worsens with exercise and improves with rest
- Abnormal posture, especially over the back and hip areas
- Reluctance to rise, run or jump
- Morning stiffness that takes time to “warm out of”
- Sitting at an odd angle, with a hind leg slanted off to one side
- Swelling (effusion) around the stifle joint
- Atrophy (withering away) of the muscles of the affected limb
All or only some of these signs may be noticed by owners. However, regardless of the severity of the injury, the signs of CCL damage usually become worse if they are not treated, because the pain felt by the dog increases as the stifle joint progressively deteriorates.
Dogs At Increased Risk
All breeds and both genders are susceptible to this injury. Rottweilers, Labrador Retrievers, Staffordshire Bull Terriers, Newfoundlands and other active, large-breed dogs seem to be at an increased risk of suffering from CCL damage. Most affected animals are in good body condition and are not systemically ill at the time of their injury. Rupture of the CCL can happen in any dog at any age, but it is more likely to occur in young, active animals. When a cruciate ligament ruptures in one leg, there is an increased chance that the CCL in the other leg will eventually become compromised, probably because of the increased weight that will be required to support the other leg as it heals.