​​Diagnosing Cruciate Ligament Disease

Cruciate ligament disease can typically be diagnosed by an experienced vet when they examine the painful knee. The examination process can be divided into: evaluation of standing patient, gait observation and orthopaedic examination. Judgement and skill are required at each of these steps to enable an accurate diagnosis in all cases. Understand that the anterior cruciate ligament that tears cannot be seen on an x-ray. Avoid thinking that your vet has to take an x-ray to make the diagnosis, it is almost always tentatively diagnosed based on physical examination techniques. Arthroscopy is the least invasive method to establish a definitive diagnosis (100% guarantee).

Pet Experience

Many owners are nervous and worried about surgical risks, pain, costs and how long their dog needs to be kept quiet after surgery. All of our surgical nursing and veterinary staff are experienced in handling your questions and enquiry – please do not hesitate to ask as many questions as you need to feel comfortable before deciding on what to do.

We typically perform surgery the day of the first consultation, but some owners like to collect information and go away to think things over a sleep on it. If you are planning on surgery the day of the consultation, your pet requires fasting overnight.

We sedate dogs following admission to hospital and then induce anaesthesia. Anaesthesia monitoring devices are then connected. We place an emergency access fluid therapy line into a vein in the front leg. Our vets will administer an epidural injection which provides powerful pain relief for 18-24 hours. We take specific digital x-rays of the affected knee and accurate measure the tibial plateau angle (TPA). The haircoat is clipped and the skin scrubbed with a topical disinfectant.

Your pet is transferred into the operating theatre and the assistant will place sterile drapes and set up the equipment. The surgeon will start with an arthroscopic examination of the knee and likely then also perform the TPLO procedure. The incision is stitched closed and an adhesive wound dressing applied to reduce infection risk. Postoperative x-ray are then performed.

Your pet is then transported into a dedicated recovery area and given a warm blanket, additional pain relief and is observed for any problems. 24 hour nursing observation is available at PESC. Typically dogs are discharged to following afternoon with oral antibiotics and anti-inflammatory medication.


There are two cruciate ligaments in the knee and they cross each other as they pass between the two main bones of the leg, the femur and tibia. If the knee is subjected to twisting when under load, a common injury is a tearing of the anterior cruciate ligament. The tear may be partial or complete and results in destabilization of the knee joint.
Trauma to the knee joint may result in injury, but that is not a common cause in dogs. Often cruciate ligament rupture is a gradual process, resulting from chronic inflammation in the knee joint. Age-related changes, poor conformation, obesity, and immune-mediated diseases are some of the more common causes. An immune-mediated disease is a condition where the body’s defense mechanism turns against itself and starts attacking the body, instead of protecting it.
Athletic or traumatic events generally cause the kind of acute cruciate ligament injuries that result in a non-weightbearing lameness with the affected limb held up off the ground. Degenerative types of cruciate ligament injuries are noted by subtle to marked intermittent lameness that goes on for weeks to months. Bilateral disease, where both knee joints are affected, is common.
Your veterinarian may suspect cruciate ligament rupture after an examination. Without the stabilizing action of the anterior cruciate ligament, the femur and tibia move in an abnormal fashion in relation to each other. This instability can be demonstrated by eliciting the ‘drawer sign’. It can sometimes be demonstrated when the dog is conscious, but in many cases, the dog requires sedation or general anaesthesia to allow proper examination of the joint.

X-rays assist in identifying arthritic changes within and around the knee joint.

Surgery to stabilize the knee joint is the best option for treatment. When the joint is unstable for a period of time, arthritic changes will begin that cannot be reversed. Some small dogs will respond to conservative treatment (i.e. without surgery) although the risk of developing degenerative joint disease is higher.

There are a few different techniques for this surgery, with new procedures continually being developed. This is to try to increase the success rate of the surgery so that the joint functions normally or near normally. Arthritis can still develop in the affected joint following surgery, but will be to a significantly lesser extent than if no surgery were performed.

Overweight dogs are more prone to cruciate ligament tears, so a weight loss program is recommended for overweight dogs. In some cases, there may be degenerative changes in the ligaments that predispose them to injury, resulting in partial tears that can progress with time to full tears, so there is a chance that the opposite knee joint may have a similar type injury in the future. The underlying reason for these degenerative changes is not fully understood.

Common Cruciate Ligament Disease Treatments

Torn cartilage