Cranial cruciate ligament (CrCL) study

Pure-bred Labrador retrievers: cranial cruciate ligament (CrCL) study
Dr. Randy J. Boudrieau, Diplomate ACVS & ECVS
Professor of Surgery
Tufts Cummings School of Veterinary Medicine
N. Grafton, MA 01536

As a summary of this study, we are radiographing (X-rays) the hind limbs of the Pure-bred Labrador retrievers (femurs, tibia and pelvis). This is a comparison study between normal dogs vs. dogs with cruciate ligament tears; (we prefer to radiograph older dogs > 6-yr, to see if they have avoided a cruciate tear, if so, then it is unlikely they will have one). We see many dogs in our hospital with cruciate tears during our day, and it is most commonly found in this breed.This is the reason we are not actively soliciting dogs with a cranial cruciate rupture (our hospital population takes care of this group).

The premise of the study is that if we can identify conformational changes that predispose to a cruciate tear, then we may have a way to prevent the problem by selective breeding.The latter is an issue to address further down the road, but first we need to prove that there is a difference between normal dogs and dogs with cruciate tears. An earlier study by the principal investigator of this study (Dominique Griffon, of Western University) showed a statistical difference in a small group of Labrador retrievers evaluated.1 The current study is a continuation of that original study, and funded by the American Kennel Club (AKC). We are now looking at a much larger pool of Labrador retrievers with greater genetic diversity (multiple areas around the country instead of a single local area). If these findings continue to hold true, then the next step in the process is initiated.

As far as the present study, there is one visit, where we only take the radiographs (seven total views). We do need to sedate the dog in order to obtain the radiographs; we use the same protocol as any dog coming into the hospital for an orthopedic (or other) evaluation that needs radiographs. As far as the sedation, we do a complete physical exam after obtaining the medical history, and also take a small blood sample to use as a quick screening test before sedation. Obviously, if there are any issues, we stop the process and discuss these before proceeding; however, since we are soliciting healthy dogs finding problems are unlikely. For the sedation itself, we (routinely) use two different drugs, so that we use less of either one individually, and one of them can be reversed after the procedure, so the dog is up and around within a few minutes (although a little sedate from the other drug that wears off in the next few hours).

If there is interest in participating in the study, please e-mail me [] or Leslie Anderson (the surgery liaison)[] and we can set up a date for an evaluation. We do try to do this at 8 AM in order to get this done before our radiology department gets busy with our normal hospitalized patients; the time frame is about 1-½ hrs in the clinic. Since we are looking at conformation, very precise radiographs are needed. It does takes a bit of time to obtain all of the requisite views.

  1. Ragetly CA, Evans R, Mostofa AA, Griffon DJ.  Multivariate Analysis of Morphometric characteristics to evaluate risk factors for cranial cruciate ligament deficiency in Labrador retrievers.  Vet Surg 40:327-333, 2011