The cranial cruciate ligament helps to stabilise the knee joint. When it is damaged, the joint becomes unstable and the dog can show anything from sudden, severe lameness to a more gradual reluctance to put weight on the hind leg. Some dogs barely put the paw down, while others still walk on the leg but get worse after activity. Swelling around the knee, difficulty getting up and reluctance to jump into the car or onto the sofa can also occur. In adult dogs, cruciate ligament disease often develops through a degenerative process in which the ligament gradually weakens. A clear injury is therefore not necessary.
The vet examines the stability of the knee and may use the cranial drawer test and the tibial compression test, among others. X-rays are often used to assess changes in the joint and rule out other causes of the lameness. The meniscus can also be damaged along with cruciate ligament disease, which can add to the pain and lameness.
Treatment is adapted to the dog's size, activity level, age, degree of instability and any other diseases. Surgical stabilisation is often recommended for dogs with obvious instability, especially larger or active dogs. TPLO is a common operation, but there are several techniques and the right one is chosen for the individual patient. Rehabilitation, controlled activity and weight control are important parts of recovery. Osteoarthritis can develop even after treatment, and cruciate ligament disease in the other knee is not unusual.