A new study from the Royal Veterinary College explores the reasons for cranial cruciate ligament (CCL) rupture in dogs in the UK, as well as the factors influencing how it is managed clinically.

The research also identifies which breeds are most at risk of CCL, with this list including popular breeds such as Rottweilers, Bichon Frise and West Highland White Terriers.

Cranial cruciate ligament rupture in the knee may be most commonly known for its major impact on the lives of footballers such as Alan Shearer or Roy Keane, but it is also a common and serious problem for dogs. Most cases in dogs are characterised by gradual degeneration of the cruciate ligament, often resulting in sudden onset pain and lameness. The findings from this new RVC research will help owners and vets to identify dogs at most risk of CCL rupture and it also highlights the clinical rationales used in first opinion veterinary practice to decide between surgery or not for the injury.

Led by the RVC’s VetCompass Programme, the study included 1,000 CCL rupture cases and a random selection of 500,000 other dogs without CCL injury. The research found that the breeds at most risk of CCL rupture, compared with crossbreeds, were Rottweiler (x 3.66 times risk), Bichon Frise (x 2.09), West Highland White Terrier (x 1.80) and Golden Retriever (x 1.69). Conversely, the breeds with the lowest risk were Cockapoo (x 0.26), Chihuahua (x 0.31), Shih-tzu (x 0.41) and German Shepherd Dog (x 0.43).

Treating CCL often involves deciding between surgical and non-surgical management. However, until now, the factors affecting this choice of clinical management of CCL rupture have not been epidemiologically analysed. The findings from this study show that insured dogs and dogs weighing over 20 kg were more likely to receive surgical management, while dogs older than 9 years 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 average 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 < 9 years had the greatest risk (x 3.24) of CCL rupture diagnosis compared with dogs < 3 years.
• Neutered females (x 1.46) and neutered males (x 1.42) were more likely to be diagnosed than entire females.
• Dogs weighing more than 30kg (x 2.19) and insured (x 2.79) were most likely to have surgery.
• Dogs over 12 years (x 0.26) and with a comorbidity (x 0.38) were least likely to have surgery.

Camilla Pegram, VetCompass PhD student at the RVC and lead author of the paper, said:

“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.”

Dr Dan O’Neill, Associate Professor in Companion Animal Epidemiology at the RVC and co-author of the paper, said:

“After centuries of reshaping by mankind, dogs now come in over 800 distinct and recognisable breeds that each has its own unique pattern of health and disease. This new study helps owners of breeds such as Rottweiler, Bichon Frise and West Highland White Terrier to understand that sudden lameness in a hindleg could indicate a ruptured cruciate ligament that needs urgent veterinary care. VetCompass studies are empowering owners to understand their dog’s health better than ever before.”

Dr Anna Frykfors von Hekkel, Lecturer in Small Animal Surgery at the RVC and co-author of the paper, said:

“This study helps to confirm suspicions we have held in the clinic, with recognition of breeds such as the West Highland White Terrier and Rottweiler being at increased risk of developing CCL disease. It offers a valuable insight into how these patients are managed in general practice and factors that might influence that challenging decision.”