You’ve probably heard of sports players tearing their ACLs and needing to sit out from quite a few games. But did you know this knee injury is prevalent in dogs and even cats? In fact, ACL injuries are one of the most common type of orthopedic injury that veterinarians see in dogs. This guide will help you potentially recognize the symptoms of a torn ACL in your pup, and better understand the treatment options that can help your pet return to a happy, healthy life.

What does the ACL do?

ACL is short for Anterior Cruciate Ligament. In dogs and cats, veterinarians technically refer to it as the Cranial Cruciate Ligament (or CCL). The dog’s ACL is found in the knee and consists of the cranial and caudal ligaments, which join the tibia (shin) and femur (thigh) bones.1 These two ligaments cross each other like an X, which allows the knee to act like a hinge. Having both ligaments intact is crucial to stabilize the knee, ensuring proper movement.

What happens when the ACL is injured?

ACL disease is a complex condition that can have multiple factors contributing to it. In people, the majority of ACL injuries are due to trauma, but in dogs, there are more factors at play. The majority of ACL ruptures are due to a degenerative condition within the knee that is sometimes compounded by trauma.

For example, a dog might be running and change direction fast, tearing the ligaments.1 An obese or older dog with degenerative changes in the ligaments might get the injury from a more minor movement, like simply stumbling.

Occasionally an ACL tear may start out with an incomplete tear, leaving your dog with a slight limp, and progress to a complete rupture, whereby the limp becomes more pronounced.