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Does Your Dog Have a Torn ACL?

In humans, a torn ACL is a common sports injury caused by a fast pivot or a blow to the knee. Dogs have a similar structure in their knees called the cranial cruciate ligament (CCL). This ligament connects the tibia (shin) and femur (thigh) and helps stabilize the knee as your dog moves. 

Damage to the CCL is among the most common sources of lameness in dogs. This means that a limp warrants a trip to the vet, even if you aren’t aware of an acute injury. An examination is necessary to help diagnose this condition. Radiographs may also be taken to determine if there are other causes contributing to the lameness.

How do cruciate ligament tears happen in dogs?

Unlike ACL injuries in humans, CCL damage is rarely the result of acute trauma. It usually occurs gradually over time and is typically discovered when the ligament is worn enough to cause instability and pain. 

It’s not fully understood what initiates the weakening of the CCL, but genetics and body type likely play a role. For this reason, 50% of dogs with a CCL will rupture the CCL in the other leg within the next year.

Risk factors for torn CCLs

Dogs with patellar luxation or chronically dislocating knees are more likely to experience a CCL tear due to force on the abnormally positioned knee.

Overweight dogs are also at a greater risk for torn CCLs due to the added stress on their joints. Your vet may recommend a special diet or exercise program to help prevent or slow ligament damage.

 Because body conformation and gait can play a role in joint health, certain breeds are more prone to sprains, including:

  • Newfoundlands
  • Labradors
  • English Bulldogs
  • Boxers
  • Westies
  • German Shepherds 
  • Rottweilers

While these are the most common breeds, CCL ruptures can be diagnosed in all breeds of dogs and even some cats.

Symptoms of a CCL tear

The severity of your dog’s symptoms will depend on the severity of the sprain or rupture. Your dog may favor the affected leg intermittently or avoid putting weight on it completely.

Lameness may come and go in the early stages. Recurrent limping should be evaluated by your veterinarian to rule out a CCL rupture. Swelling of the knee joint and thickening of the joint capsule can also indicate a CCL rupture. Particularly in larger dogs, weakened or ruptured CCLs will cause knee instability, leading to painful bone spurs and arthritis. 

Treatment for CCL injuries in dogs

Initial injuries and partial tears are often treated with NSAIDs.  Full tears and strongly suspected partial tears often require surgery. 

There are multiple options for CCL surgery to stabilize the knee and limit pain and arthritis formation. The best choice depends on many factors, including the size of your pet, their activity level, and the presence of patellar luxation. Your veterinarian will conduct an examination and recommend the best course of treatment for your dog’s CCL repair.

Most dogs will have some degree of osteoarthritis (OA) after surgery that will need to be managed. Joint supplements, laser therapy, physical therapy (including the underwater treadmill), and long-term medications are sometimes needed.

If you suspect your dog may be dealing with a CCL rupture, don’t hesitate to reach out to your vet about treatment options. Early intervention is the best way to protect your dog’s joint health now and in the future.