A Genetic Test for Cruciate Ligament Rupture Risk in the Labrador Retriever
By Sharon Albright, DVM, CCRT
Manager of Communications & Veterinary Outreach, AKC Canine Health Foundation
Cruciate ligament rupture is one of the most common orthopedic diagnoses in small animal clinical practice. It is like an ACL rupture in humans. In dogs, the cruciate ligament tissue frays little by little over time. Continued activity, joint instability, and inflammation eventually lead to complete tearing of
the ligament. Surgery to stabilize the stifle (knee) joint is the recommended treatment and it is estimated that more than $1 billion is spent on surgical and medical management of canine cruciate ligament rupture in the United States each year.1 Dogs can often return to full activity following surgical repair and rehabilitation therapy, but it is a long and expensive journey.
Certain breeds, such as the Labrador Retriever, Rottweiler, and Newfoundland are at higher risk of cruciate ligament rupture, indicating a genetic influence on disease development. But which genes are involved and how much impact do they have on an individual dog’s risk of cruciate ligament rupture? Investigators at the University of Wisconsin set out to answer these questions with funding from the AKC Canine Health Foundation (CHF).
Analyzing genetic data from just over 1,000 Labrador Retrievers, investigators found that the heritability of cruciate ligament rupture in Labs is estimated at 0.62. This means that 62% of the risk comes from genetic factors, with the remaining 38% resulting from environmental factors. Specific environmental factors that influence risk of cruciate ligament rupture are poorly understood.
There are many genes with thousands of variants that influence risk of cruciate ligament rupture in Labrador Retrievers. While this seems overwhelming, investigators have been able to develop a genetic test that predicts whether a Labrador is at high risk for the disease.
“It’s important to understand that this test is predictive for disease risk,” says Principal Investigator Dr. Peter Muir. “Cruciate ligament rupture is a common complex disease. This test determines an individual dog’s risk of the disease, which is not the same as genotyping for a simple dominant or recessive trait.”
Test results will be either ‘predicted to be a case,’ meaning the dog has genetic markers that predict it will likely develop cruciate ligament rupture, or ‘predicted to be a control,’ meaning that it is unlikely to develop the disease. Predictive accuracy in the reference population used to develop the test was 98%.
“If a dog receives the ‘high genetic risk’ result, it is highly likely that dog will develop a cruciate ligament rupture in its lifetime,” Dr. Muir says. “But that risk could be reduced by personalized veterinary care once we better understand the relevant environmental risk factors that we can modify.”
Owners of low-risk dogs must remember that their dogs still have a chance of developing cruciate ligament rupture because of environmental risk factors. In this regard, body condition is likely important.
How can breeders use this test? Because a large number of genetic variants influence risk of cruciate ligament rupture in the Labrador Retriever, breeding two low-risk dogs could produce high-risk puppies and vice versa. However, over time, the incidence of cruciate ligament rupture in this breed should decline if we continue to breed low-risk to low-risk dogs.
The genetic risk test for cruciate ligament rupture in Labrador Retrievers is an exciting development. It is one of the first genetic tests available for a canine complex disease. Results can inform breeding strategies to decrease the incidence of the disease in future generations of Labrador Retrievers. Owners of high-risk dogs can prioritize personalized care with their veterinarian to minimize modifiable environmental risk. While Labrador Retrievers continue playing and working without interruption, CHF will continue to find and fund ground-breaking studies like this to help all dogs live longer, healthier lives.
For more information about cruciate ligament rupture genetic test availability, visit www.vetmed.wisc.edu/lab/corl/canine-genetic-testing/.
1. Wilke VL, Robinson DA, Evans RB, Rothschild MF, Conzemius MG. Estimate of the annual economic impact of treatment of cranial cruciate ligament injury in dogs in the United States. J Am Vet Med Assoc. 2005 Nov 15;227(10):1604-7.
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Posted by Liz
on Oct 29 2022. Filed under Featured, Health & Training, The Buzz.
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