Studies analyze factors, outcomes associated with cranial cruciate ligament rupture, surgery

Two recent studies out of the U.K. seek to provide better guidance for diagnosing and treating one of the most common causes of lameness in dogs: injuries of the cranial cruciate ligament.

Cranial cruciate ligament disease is caused by a combination of many factors, including degeneration, obesity, poor physical condition, genetics, and breed.

New research from the University of London Royal Veterinary College explores risk factors for cranial cruciate ligament rupture in dogs in the U.K., as well as those factors influencing how CCL rupture is managed clinically.

Rottweiler entering a rehabilitation pool
Cranial cruciate ligament rupture is a common and serious problem for dogs. New research looked at 1,000 CCL rupture cases and a random selection of 500,000 other dogs without CCL injury.

The study, published in the February 2023 issue of The Veterinary Journal, was led by the RVC’s VetCompass program, which collates data from electronic patient records at primary care veterinary practices throughout the U.K. for epidemiological research. The study looked at 1,000 CCL rupture cases and a random selection of 500,000 other dogs without CCL injury examined at practices participating in the VetCompass program.

The research found that the breeds at most risk of CCL rupture, compared with crossbreeds, were as follows:

  • Rottweiler, at 3.66 times the risk.
  • Bichon Frise, at 2.09 times the risk.
  • West Highland White Terrier, at 1.80 times the risk.
  • Golden Retriever, at 1.69 times the risk.

The breeds with the lowest risk were Cockapoo, at 0.26 times the risk; Chihuahua, at 0.31 times the risk; Shih-tzu, at 0.41 times the risk; and German Shepherd, at 0.43 times the risk.

Treating CCL rupture often involves deciding between surgical and nonsurgical management. However, until now, the factors affecting clinical management of CCL rupture have not been epidemiologically analyzed, according to the study’s authors.

The findings indicate that insured dogs and dogs weighing over 44 pounds were more likely to receive surgical management, while dogs 9 years and older and those with another major clinical problem at the time of diagnosis with CCL rupture were less likely to receive surgical management.

Additional key findings include the following:

  • The median age at first diagnosis of CCL rupture was 7.4 years, showing CCL rupture as mainly a disease of middle-aged and older dogs.
  • Dogs aged 6 to 8 years old had the greatest risk—at 3.24 times the risk—of a diagnosis of CCL rupture compared with dogs less than 3 years old.
  • Spayed females, at 1.46 times the risk, and neutered males, at 1.42 times the risk, were more likely to be diagnosed with CCL rupture than intact females.
  • Dogs weighing 66 pounds or more had 2.19 times the odds of surgery compared with dogs weighing less than 22 pounds.
  • Insured dogs had 2.79 times the odds of surgery compared with uninsured dogs.
  • Dogs 12 years and older had 0.26 times the odds of surgery compared with dogs less than 3 years old.
  • Dogs with a nonorthopedic comorbidity had 0.38 times the odds of surgery compared with dogs with no comorbidity.

Camilla Pegram, a VetCompass doctoral student at the RVC and lead author of the paper, said in a press release from the college: “This study has used the power of ‘big data’ to robustly address the risk factors for cruciate ligament rupture diagnosis and management in dogs. The factors affecting the decision to surgically or non-surgically treat dogs with cruciate rupture are now clearer, with future work underway to address the clinical outcomes of this decision.”

To that end, a study published Feb. 2 in PLOS One is the first academic paper to use data from the Canine Cruciate Registry from RCVS Knowledge, the charity partner of the Royal College of Veterinary Surgeons. The research investigated the minimal clinically important differences for two client-reported outcomes measures, or CROMs, as they related to dogs undergoing surgical CCL repair.

The first CROM, Liverpool Osteoarthritis in Dogs, was developed at the University of Liverpool and licensed to Elanco, while the second, the Canine Orthopedic Index, was developed by the American College of Veterinary Surgeons. LOAD and COI are a series of pre- and post-treatment questionnaires, answered by owners, that give a numerical score to track recovery. Previously, they had only been validated for the evaluation of canine osteoarthritis.

Minimal clinically important differences, defined as “the smallest change in the score of an outcome measure that a client would identify as important,” are useful for investigators and regulators so that these outcomes measures can be used in clinical trials. These measures are also useful in the context of monitoring patients’ responses to interventions and in clinical decision making.