Knee injuries in dogs – cruciate disease

1st September 2017


What is the cruciate ligament?

The knee or stifle joint in dogs has the same structures as you find in humans and is subject to the same kind of injuries. Cruciate ligament damage is very common in footballers and athletes with the damage often occurring as a result of sudden twisting or turning movements. These problems also happen in dogs when out playing and chasing.

The cruciate ligaments are inside the knee and join the femur (thigh bone) and tibia (shin bone) together. They are called “cruciate” ligaments because they cross over each other inside the knee.

The cranial cruciate ligament limits twisting and excessive forward movement of the tibia and prevents over extension. It’s essential for the stability of the knee joint.


What is cruciate disease?

Cruciate disease is a complex problem with many triggers and is fundamentally caused by partial or complete rupture of the cranial cruciate ligament. This results in instability of the knee joint, which in turn causes abnormal wear and tear of the cartilage in the joint and osteoarthritis.

The ligament tear may be as a result of an acute injury, such as the dog turning quickly or jumping and landing awkwardly, or through degenerative changes of the ligament, which results in weakness and eventual rupture during routine exercise or walking.


Which dogs are at risk?

  • Young dogs - acute injuries are often seen in young boisterous dogs. They are particularly at risk when twisting and turning abruptly, as the forces on the ligaments within the joint can be quite extreme.
  • Older dogs – the degenerative form of the disease is commonly seen in elderly animals.
  • Medium and large breeds – at Bollington Veterinary Centre we often see Labradors, Rottweiler’s and Boxers with cruciate damage.
  • Obesity – for many dogs being overweight can be an important contributing factor for ligament damage. If an animal is extremely heavy the forces within the joint can be exaggerated and trigger the ligament to rupture.


How do we diagnose cruciate disease?

The rupture of the cranial cruciate ligament will cause varying degrees of lameness and can lead to cartilage damage and arthritis within the knee joint.


Signs we look for include;

  • Acute lameness - sudden onset limping, often immediately after letting out a yelp.
  • Progressive lameness – the degenerative form of cruciate disease can start will a mild intermittent lameness, which slowly develops into a full time non-weight bearing lameness.
  • Joint instability – if we suspect a problem with the knee joint we’ll feel and move the joint trying to detect instability, abnormal movements or clicking sounds.
  • Swollen joint – with the progression of the disease, there will be significant inflammation which will cause a joint effusion (fluid collecting inside the joint).



Xrays will usually be taken under sedation or anaesthesia to rule out other causes of lameness and assess the degree of arthritis.


How do we treat cruciate disease?

If a rupture of the cruciate ligament is confirmed, surgery is usually recommended. There are several techniques that can be used and our vets will need to talk you through all the advantages and disadvantages.

After surgery animals are placed on pain killers, anti-inflammatory drugs and a regime of rest and controlled exercise. Most animals have good functional improvement after the surgery, but degenerative joint disease and osteoarthritis develops in most dogs in the long term.

Non-surgical treatment is rarely suggested unless the risks of surgery or an anaesthetic are significant. Patients with severe heart disease or another debilitating condition may be managed with weight loss, physiotherapy, controlled exercise and anti-inflammatory treatments.

Generally dogs over 15kg have a poor chance of improving with non-surgical treatment. Dogs weighing less than 15kg have a better chance, though it usually takes months to improve and may not fully resolve.

Watch this video

This video on YouTube was made for Edinburgh Vet School and shows very clearly what the cruciate ligaments are and how they cause instability of the knee joint when ruptured.