Signs of a Torn Cruciate Ligament in a Dog's Hock

There are two cruciate ligaments in a dog's hock---the anterior cruciate ligament and the posterior cruciate ligament . These two ligaments hold the three bones of the knee together. When they rupture, or tear, the joint becomes unstable. Usually the result of injury or degenerative disease, ACL and PCL tears are identified by specific symptoms.

  1. Lameness

    • Dogs with a torn ACL or PCL exhibit lameness, according to the "Clinical Veterinary Advisor." They may not try to walk, or may avoid walking more than is absolutely necessary. When a dog with a torn cruciate ligament does walk, it appears to favor the leg with the injury by avoiding placing pressure on it. The lameness may disappear for a time, but quickly returns as the pain of bearing pressure on the leg increases, as stated in the "Clinical Textbook for Veterinary Technicians."

    Swelling

    • The hock, or knee, affected by the ruptured ligament will swell, frequently up to twice its normal size, according to the "Clinical Textbook for Veterinary Technicians." In addition to this, the side of the leg that faces the opposite leg will become swollen or locked. This is termed a medial buttress and serves to cushion the joint. Medial buttress formation is also an indication that arthritis is developing in the hock, according to the "Merck Veterinary Manual."

    Pain

    • Dogs with a torn cruciate ligament are in pain. When pressure is placed on the leg with the torn ligament, the dog may cry or howl in discomfort. Dogs may react with fear-based aggression when the leg is handled, and may vocalize when the hock is touched, even lightly, according to the "Clinical Textbook for Veterinary Technicians."

    Abnormal Movement

    • A hock with a torn cruciate ligament moves abnormally when examined and manipulated by a veterinarian. This is the most definitive sign of a torn cruciate ligament. The femur is stabilized by the veterinarian with one hand. With the other hand, the vet moves the tibia. Dogs with torn cruciate ligaments will have a tibia that moves forward, a movement likened to the opening of a drawer, hence the colloquial name "drawer test." In healthy dogs, the tibia cannot move in this manner, according to "Canine Anatomy." Due to the pain and fear associated with this injury, many dogs need to be sedated or anesthetized for the veterinarian to perform this test.