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ACL (anterior cruciate ligament) Rupture in Dogs

Cranial (or anterior) cruciate ligament (CCL) rupture is one of the most common orthopedic conditions seen in the dog. Unlike in people, where trauma is the most common etiology of the disease, canine CCL rupture is multifactorial in origin. Regardless of cause, CCL rupture results in stifle instability which sets into motion a cascade of events including synovitis, articular cartilage degeneration, periarticular osteophyte development, capsular fibrosis and medial meniscus injury. (Figure 2) Progressive osteoarthritis is the end result after cranial cruciate ligament rupture regardless of treatment; however, the severity of osteoarthritis may be attenuated with early surgical intervention.

Causes for ACL rupture in Dogs

CCL rupture may be acute or chronic in nature. Acute injury to the CCL is usually traumatic in origin and is a reflection of its function as a stabilizer of joint motion. Acute injury is most commonly associated with hyperextension and internal rotation of the leg which occurs when the dog steps in a hole or becomes ensnared in a fence. Jumping can also cause cruciate ligament rupture if the forces stressing the ligament exceed its breaking strength. Proposed underlying etiologies for chronic disease include age related deterioration to the ligament structure, obesity, conformation abnormalities (straight rear limb conformation), and immune mediated disease. With ligament degeneration, even repetitive normal activities can cause progressive rupturing of the ligament.

Incidence and Prevalence of ACL rupture in Dogs

Either sex and any age or breed of dog may be affected. CCL injury is rare in cats. Recent epidemiological studies have suggested that younger, more active large breeds of dogs may be predisposed to CCL rupture.

Signs and Symptoms

Depending upon the nature of the injury (acute or chronic) and whether the rupture is complete or partial, the clinical presentation can vary from a subtle lameness associated with exercise to a full non-weight bearing injury. Patients with acute tears usually present with a non-weight bearing or partial-weight bearing lameness of sudden onset. This lameness usually improves within 3 to 6 weeks after injury without treatment, particularly in patients weighing less than 10 kg (25 lb). Retrospective studies of dogs weighing less than 10 kg indicate that they typically have adequate clinical function with conservative treatment. In mid-size and large breed dogs, the lameness associated with CCL injury improves but the animal never returns to full athletic function without evidence of recurring lameness. Furthermore, a knee deficient of a CCL predisposes the animal to injury to other structures within the knee, such as the menisci, which are the shock absorbers of the knee. Damage to the menisci results in progression of the osteoarthritis and lameness. Partial cranial cruciate ligament tears are difficult to diagnose in the early stages of injury. Initially, affected animals have a mild weight-bearing lameness associated with exercise, and until degenerative changes develop, the lameness resolves with rest. Later, however, as the ligament continues to tear and the stifle becomes increasingly unstable, degenerative changes worsen and lameness becomes more pronounced and does not resolve with rest.

Read the full article at the American College of Veterinary Surgeons (who are specialists in surgical repair of this condition):

NB: From my perspective as a vet homeopath, most pets with cruciate rupture are energetically (and immune) imbalanced. This is especially true if the rupture is not due to an obvious trauma. I therefore address the internal imbalance before advising any surgical intervention. In addition, a program of optimal nutrition and supplementation is often beneficial. I am excited to also be evaluating the clinical response to the new bone morphogenetic protein product that is now available.


Please note: The information provided here is intended to supplement the recommendations of your veterinarian. Do not disregard veterinary advice or delay treatment based on information on this site. Nothing can replace a complete history and physical examination performed by your veterinarian. -Dr. Jeff