Cranial cruciate
ligament rupture
in dogs & cats

What are the symptoms?

The signs you see vary with the stage of the condition and the extent of the rupture. Owners often describe:

• a sudden lameness in one hind leg;
• a lameness that has come on gradually over several weeks or months;
• a temporary improvement after a few days of rest;
• a good response to anti-inflammatories followed by a relapse once the treatment is stopped;
• difficulty getting up after resting;
• a reduction in physical activity;
• a reluctance to run, jump or climb stairs;
• progressive muscle wastage in the thigh of the affected limb.

In some dogs the lameness is very pronounced from the outset. In others it stays subtle but persistent for several months. This fluctuating course is particularly characteristic of partial ruptures or degenerative lesions of the cruciate ligament.

What happens inside the knee?

The cranial cruciate ligament is one of the main stabilisers of the knee (stifle). When it is healthy, it stops the tibia from sliding abnormally beneath the femur during movement.

When it ruptures, even partially, this stability is lost. With every step, the joint undergoes abnormal movements that cause pain, inflammation and progressive wear of the cartilage.

Over time, this instability also encourages the development of osteoarthritis, sometimes severe, even in relatively young dogs.

Why does the lameness keep coming back?

When the cruciate ligament is damaged, the knee becomes unstable.

Anti-inflammatories can often reduce the pain and inflammation present in the joint. The dog then appears to be doing better and returns to more normal activity. The treatment, however, does not repair the ligament.

The instability of the knee persists and continues to cause joint inflammation. As soon as the medication is stopped, or with slightly more strenuous activity, the pain usually reappears and the lameness returns.

This is why many owners feel that their dog gets better and then relapses again and again.

How do we diagnose a rupture?

At Colvet, the diagnosis rests above all on a thorough orthopaedic examination, both while the animal is awake and under sedation. We take the time to watch your dog's gait, assess the joints involved and look for the signs of instability that are characteristic of a cruciate ligament rupture.

The manipulations that allow us to confirm a cruciate ligament rupture are often painful, and X-rays require us to place the animal in uncomfortable positions. This is why, most of the time, sedation will be needed to confirm our suspicion.

These radiographs allow us to assess the knee, look for signs of osteoarthritis, rule out other causes of lameness and prepare for any surgery that may be required.