One of my soapbox issues in veterinary sports medicine is cruciate ligament disease. I say disease rather than just an injury because there are a host of factors that contribute to this condition.
What is the Cruciate Ligament?
When we think about cruciate issues in dogs, it’s usually the cranial cruciate ligament (CCL) we’re talking about—this is equivalent to the ACL (anterior cruciate ligament) in humans. Whether talking ACL or CCL it is the front ligament of the two in both species. The primary role of this ligament is to prevent the shin bone (tibia) from sliding forward relative to the thigh bone (femur). During an exam, we’re assessing this movement through tests like the “drawer sign” and “tibial thrust.”
Diagnosing a Cruciate Injury: It’s Not Always Clear-Cut
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.
The Many Factors Behind Cruciate Ligament Disease
Like in humans, cruciate ligament injuries in dogs can occur as a result of athletic activity. Every hunting season, I’m reminded just how athletic these dogs are and how incredible it is that we don’t see more injuries. I can’t count the number of times I’ve misstepped into a badger hole, feeling like I was about to snap something, and I’m just walking! These dogs are running full tilt through rough cover, and they rarely miss a step—it’s truly remarkable.
However, genetics also play a significant role. Nearly 20 years ago, in 2006, Dr. Vickie Wilke and her colleagues at Iowa State University published research on the inheritance of cruciate disease in Newfoundland. I had the opportunity to interview Dr. Wilke during the early days of my gundog podcast series in 2008. Back then, she was optimistic about having a genetic test for Labradors within a year. It took a bit longer, but the University of Wisconsin recently started offering a test to assess cruciate rupture risk in Labradors.
Genetic Testing: A Double-Edged Sword?
Despite the availability of genetic testing, I’ve only had a handful of inquiries about it. Genetics in dog breeding is a complex topic. The tests provide valuable information to make better breeding decisions, yet many breeders shy away from using them, often due to misunderstandings. Some view the results as a “scarlet letter” rather than a tool for informed decision-making.
The challenge with genetic testing is that it’s rarely as simple as the Mendelian genetics you learned in school. For conditions where carriers do not display the disease, breeders may be quick to only breed “clear” dogs. This approach can inadvertently reduce genetic diversity and create bottlenecks, potentially leading to new, more serious health issues.
In my experience, breeders tend to respond in one of two ways:
- Ignoring the tests: Claiming, “I don’t see that in my lines,” or casting doubt on the validity of the test.
- Overly restrictive breeding: Choosing only to breed dogs that test clear, which can unnecessarily eliminate good genetics from the breeding pool.
Health tests should be used as one factor in the decision-making process, not as the sole determinant. The mode of inheritance plays a critical role, and not all traits follow the same genetic patterns.
The Bigger Picture: Why Focus on the Larger Issue?
In the case of cruciate ligaments, I believe we have more pressing concerns across many sporting breeds beyond just focusing on the genetic test for Labradors. Unfortunately, breeders have long been given a pass on breeding dogs with poor knees simply because it’s a “fixable” problem. It’s baffling to me that while breeding dogs with bad hips would be met with outrage, breeding dogs with bad knees doesn’t raise the same red flags.
Perhaps it’s because I see firsthand the heartbreak this causes dog owners. For those who have just one or two dogs, having a dog sidelined for 10-12 weeks (often twice) due to surgery is devastating. These are people who have invested thousands of dollars in a puppy, only to find themselves spending even more on surgeries before their dog has even had a chance to hunt. It’s not out of the realm of possibilities for these owners to have 10-20k invested in a dog that is 2-4 years old and has never spend a day in the field.
What Can Puppy Buyers Do?
As a buyer, it’s crucial to ask breeders tough questions. While a genetic test can provide early insights, once a dog has a cruciate injury (or two), you already have enough information to make decisions about breeding. It should be unacceptable for breeders to continue selling puppies or semen to recoup their investments without regard for the health of future generations.
Expanding Issue Across Breeds
Earlier in my career, cruciate issues were primarily seen in Labs and Goldens. However, we’re now seeing this problem in breeds where it used to be rare. These days, I feel just as likely to see a blown cruciate in a German Wirehair, Shorthair, or Pointer as I am in a Lab or Golden.
I suspect that the cause isn’t purely genetic in the traditional sense. Instead, as Americans, we’ve likely altered the conformation of these dogs to fit a certain aesthetic. This has potentially led to changes in joint angles, which, in turn, contribute to ligament injuries.
Prevention is Better Than Correction
As with many conditions, prevention is far better than correction. Ideally, you’d choose a dog from lines that don’t have a history of cruciate problems, so you’d never have to face the ordeal of surgery. This starts with thoroughly researching both the breed and specific lines.
If your dog is already limping, getting an accurate diagnosis is crucial to ensure a speedy recovery and a return to the field.
Coming Up Next: Surgical Repair Options
In the next post, we’ll dive deeper into the surgical repair options for cruciate ligament injuries and what you can expect during recovery.
