Diagnosing Cranial Cruciate Ligament Tears in Dogs – Dr. Loudon

When a dog presents with lameness, particularly in one of the hind legs, veterinarians often suspect a cranial cruciate ligament (CCL) tear.

• Diagnosis is typically made by a combination of physical examination and diagnostic imaging.
• One of the key diagnostic tests used by veterinarians is feeling for what’s called the cranial drawer sign. This test involves palpating the knee joint to assess for abnormal movement, which indicates laxity and damage to the CCL.
  • The cranial drawer test is one of the most reliable indicators of a CCL tear.
• The tibial Compression Test is similar to the cranial drawer test, it evaluates stability of the tibia relative to the femur.
  • Instability on this test is referred to as cranial tibial thrust. The test is more sensitive with the animal under sedation.
• In some cases, your dog may need a mild muscle relaxant or sedative to help the veterinarian perform the test accurately, especially if the dog is in pain or too tense.
• If the diagnosis is still unclear after the physical exam, or if the vet wants to rule out other causes of lameness, they may recommend radiographs (X-rays) to assess for any other issues like fractures or arthritis.
• Before surgery, an orthopedic surgeon may also recommend advanced imaging like a CT scan or MRI to get a clearer picture of the injury, particularly if the diagnosis is uncertain or if there are concerns about additional soft tissue injuries.

Diagnosing a Cruciate Injury: It’s Not Always Clear-Cut – Gun Dog Doc

When people mention a “partial tear,” this is often based on how the cruciate bands respond to flexion and extension during the physical exam. It’s important to assess drawer motion in both extension and flexion to distinguish between partial and complete tears.

A couple of critical points about diagnosing cruciate injuries:

• X-rays don’t show cruciate ligaments: You can’t actually see the ligaments themselves on an X-ray.
  • However, you can spot indirect signs of cruciate disease, like joint effusion, displacement of the infrapatellar fat pad, or—in rare cases—drawer displacement. But, for all practical purposes, an X-ray only provides evidence, not a definitive diagnosis.
• MRI can visualize cruciate ligaments, but it’s costly: Given the expense, you might be looking at nearly the same cost as the surgical repair itself.
• Most diagnoses are made based on a thorough physical exam. However, this isn’t always straightforward, especially with larger, well-muscled dogs. I experienced this firsthand when I tore my own ACL and meniscus nearly 25 years ago. It took multiple exams and even a misread MRI before I got an accurate diagnosis.
• If your dog has rear leg lameness and your vet suspects a cruciate injury but isn’t certain, there’s no shame in seeking a second opinion from someone who regularly performs these exams.
  • Too many dogs go undiagnosed or are improperly treated because they didn’t get a thorough assessment.