The question below was featured in the Summer 2017 issue of On Call, the magazine for friends of the UW School of Veterinary Medicine. This issue’s response comes from Jason Bleedorn, MS’15, clinical associate professor of orthopedic surgery and board-certified veterinary medical surgeon.
Please send them to our On Call magazine editor at firstname.lastname@example.org. We cannot guarantee responses to all submissions. For any urgent pet health issue, please contact your veterinarian directly.
Question: Why is there a one-month waiting period to repair a canine ACL tear? My dog cannot walk — why isn’t that considered an emergency? —Donna, Janesville, Wisconsin
Answer: The cranial cruciate ligament in dogs functions much the same as the anterior cruciate ligament in humans. It stabilizes the knee joint (called the stifle joint in dogs) as it rotates and bends. Cruciate rupture is a common condition in dogs, most often resulting from chronic degeneration of the ligament (unlike in humans where athletic activity is typically the culprit).
Many factors are involved in this condition, but baseline genetic risk, environmental conditions, and an animal’s proportional size and shape are commonly involved. The process typically begins with joint inflammation and small ligament fiber fraying and then progresses from partial to complete ligament failure over a variable amount of time. Dogs with a rupture may be able to bear mild to moderate weight, and pain is typically well controlled with medical therapy.
Treatment focuses on alleviating pain, maintaining mobility and muscle mass, and stabilizing the joint with surgery. Since this condition in dogs stems from a chronic degenerative process, the timing of intervention has little impact on the ultimate prognosis. Although it can be difficult to see your pet limp or show signs of pain, there is some evidence in humans to suggest that actually delaying surgical treatment for several weeks can allow inflammation to subside. This has not been investigated in dogs primarily because it is more difficult to pinpoint when their ruptures occur.
Often, diagnosis and treatment are delayed in dogs because the clinical signs may be mild at the onset and owners may not seek veterinary medical care. Surgery is often recommended for dogs with unstable (full cruciate rupture) joints or those with persistent lameness despite medical management. Ultimately, stifle arthritis is progressive with cruciate rupture despite current medical and surgical options.
Owners are encouraged to speak to their veterinarians about cruciate rupture in dogs. Board-certified veterinary medical surgeons experienced with this condition can also help guide individualized patient care.