Dog CCL Injury Diagnosis: Is There Such a Thing As A False Positive Drawer Sign?

A therapist or a veterinarian will perform the drawer test using their hands. The test is positive if the tibia slides too far forward.

Faced with a life-altering diagnosis, whether temporarily or for the rest of the dog’s life, we look for ways out. “Maybe it is something else, something that will go away on its own.”

I was in the same boat when the vet suspected an ACL injury as a reason for Jasmine’s limp. All I wanted was a different diagnosis.

No wonder I felt for a friend of mine, asking whether there was such a thing as a false positive drawer sign. Is there?

Dog CCL Injury Diagnosis: Is There Such a Thing As A False Positive Drawer Sign?

Diagnosing CCL injuries

Your veterinarian might diagnose cruciate ligament injury based on a physical evaluation. The two things their look for are:

  • joint swelling or thickening
  • instability of the stifle

The two tests your veterinarian might perform to evaluate stifle stability likely are:

  • cranial drawer test
  • tibial compression test

Tibial compression test

The tibial compression test—cranial tibial thrust—is useful because it mimics what happens in the knee when the dog walks. If there is CCL damage, the bone moves forward when the hock is in the flexed position. This makes it different from the drawer test, a motion that doesn’t happen in real life.

Further, this test is more accurate and reliable. Yet, the tibial compression test isn’t as familiar as the drawer sign.

Further information: Diagnosis of Cranial Cruciate LigamentIinjury in Dogs by Tibial Compression Radiography

The drawer sign

A drawer sign, or drawer test, is a diagnostic manipulation to determine CCL injury in a dog’s knee. Generally, If there is any abnormal movement in the joint, the test is positive.

Dog CCL Injury Diagnosis: Is There Such a Thing As A False Positive Drawer Sign?
Healthy and torn cruciate ligament. Image PDSA

Take a quick look at a dog’s knee anatomy. The joint parts don’t nest within each other, such as in the hip joint. Rather, one part is pretty much sitting on top of the other. Ligaments within the knee contribute to joint stability.

The anterior/cranial cruciate ligament ACL/CCL and the posterior cruciate ligament are the two ligaments that are crucial to knee stability. One is holding the joint parts in place front-to-back and the other back-to-front. The ACL/CCL ligament is susceptible to tearing.

During the drawer test the veterinarian with stabilize your dog’s femur (thigh bone) with one hand while manipulating the tibia (shin bone) with the other. If the tibia moves forward—known as a positive drawer because of the way the bone moves similar to a drawer being opened—the ligament is ruptured.

DogKneeInjury.com

Positive drawer test

The test is positive if the tibia slides too far forward. Picture it as pulling a drawer from a chest or cabinet. The test is positive if the veterinarian can manipulate the knee in that way.

The ligament damage grades 0-5 according to the amount of excessive tibial movement in millimeters. Here is what the scoring means:

  • 0 means no tear
  • 1-2 indicates a partial tear
  • 3 is partial to nearly-full
  • 4-5 indicates full tears

False-netagive cranial drawer test

Your veterinarian might not always be able to get a positive result, especially in a lucid dog. The inability to elicit the drawer sign, unfortunately, doesn’t rule out ligament damage.

Many dogs need to be sedated before the presence of the drawer sign can be ruled out.

False-positive tests

It appears that the tibial compression test is superior to the more popular drawer test. The drawer test is more likely to have false-negative results. Further, according to the study below, it can have false-positive results as well.

Based on those results, there is indeed such a thing as a false-positive drawer test.

Further information: Diagnosis of Cranial Cruciate LigamentIinjury in Dogs by Tibial Compression Radiography

Summary

The easiest way to confirm whether there is indeed damage to the stifle ligament seems to be following the drawer test by the tibial compression test. Radiographs can further assist in confirming the diagnosis. The one thing you do not want is to have your dog undergo surgery that is not necessary.

There are more advanced diagnostics that can provide a definite picture of the state of the ligament such as MRI or arthroscopy. However, those are both expensive and invasive.

Still, though, the rule applies, measure twice and cut once.

Related articles:
Talk To Me About Dog ACL/CCL Injuries: My Dog Ruptured Their Cruciate Ligament
Canine Cranial Cruciate Ligaments: Hanging by a Thread? Stabilizing Forces in the Canine Stifle
Dog CCL Injury Grading
Dog Knee Injuries: Why The Second CCL Often Goes Too

Further reading:
Canine Cranial Cruciate Disease: Updating Our Knowledge about Pathogenesis & Diagnosis

Categories: CCL injuriesJoint issuesKnee issues

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Jana Rade

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience.

9 Comments
  1. Really interesting and SO important to know. I would say, based on the likelihood of a false positive, that any dog owner faced with this diagnosis should trust their gut. If something feels ‘off’ or not right, get a second opinion. This isn’t to day that your second opinion will always differ from the first but at least you know.

  2. I wonder why more vets don’t do the tibial compression test and insist on the drawer test. It would seem they would want to do the test that would give more accurate results.

  3. Oh wow, this is really good to know. I’ve never had a dog with a CCL but I’ve known a few people who have experienced it with their dogs. Even though the drawer test isn’t perfect, it sounds like a good place to start before moving forward with more invasive options.

  4. robincrittear

    CCL injuries must be so painful for the dog! I can see after reading your description and watching the videos how both tests can be very important to properly diagnose the injury. Thank you for explaining these things because veterinarians are not always good at explaning what is going on when they are performing tests on your pet.

  5. My first thought is ‘Ah ha’ so this is why a vet will flex a limb. They are looking for something very specific that I, a layman, might not understand (without help like this).

    Your post allows me to understand why the vet might do something and I can make a more informed comment or ask a question knowing what is happening as a result. Thank you.

  6. Great detailed information on CCL injury and diagnosis. The videos, in particular, were very helpful to see what it is and how it is diagnosed. It’s sad to see and must be incredibly painful. I’m glad I personally haven’t dealt with this issue. However, I’ve had many dog parents friends who have and are currently struggling with CCL issues. Thank you for this information!

  7. Great post and always good to know ahead before something happens so that you know what to discuss with your vet and more aware of it all

  8. Very interesting! I know about CCL injuries in general but, as I’ve never had to deal with one personally, I didn’t know much about how they are diagnosed.

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