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Cruciate disease in dogs

What is cruciate disease ?

The cruciate ligaments are important stabilising ligaments of the knee (stifle) joint. The stifle joint consists of the femur, the tibia, the patella (the kneecap) and a small fabellae behind the joint. Cushioning cartilage, called menisci, are between the femur and tibia, and ligaments hold the joint together, allowing the normal motion of the knee through flexion (bending) and extending. They also stabilise the knee to prevent the knee from bending a way it shouldn’t.

There are two cruciate ligaments that cross inside the stifle, the cranial and the caudal ligament, and they help prevent the tibia from slipping forwards under the femur.

A ruptured cruciate ligament is the most common stifle injury in dogs. A history of a sudden onset (acute) hindlimb lameness is the usual scenario. They may be suddenly lame and unable to bear weight on the affected hind limb, or partially bear weight (toe touching). The lameness may appear to improve initially. They may start to sit differently with their affected limb out to the side. The stifle joint may become swollen. If left unaffected, the joint will start to form arthritis, which will reduce the range of motion of the joint and will be chronically sore.

Cranial cruciate rupture can be a full rupture or a partial tear. Injuries most commonly occur in large breeds, but can also happen in small breeds. Ruptures can happen at any age. In young breed dogs it is usually when they are at full speed or playing rough and take a bad step, presenting as an acute hindlimb lameness.

Older, overweight dogs are more prone to chronic partial tears as their ligaments can be weakened and slowly stretched due to overloading of the joint. A partial rupture may not be detected until the ligament breaks completely. This type of patient may then experience a full rupture just from stepping down off a bed, or from jumping. Smaller breeds that suffer from luxating patella have an increased predisposition of cranial cruciate rupture as the ligament is under more stress.

Unfortunately, the odds of a rupture to the other limb are high, and this can be within a year of the initial limb being affected. The chance of a contralateral limb cruciate injury is more likely if the patient is older and overweight; owners should be prepared for another surgery in this time frame.

Cruciate disease in a dog

How do you diagnose cruciate disease?

Diagnosis is based on history, clinical signs and manipulation of the joint, with radiographs (X-rays) being the best way to rule out other causes of hind limb lameness, for example tibial crest avulsions, bone tumours, or fractures. They will also show any signs of arthritis, or the degree of arthritis present within the stifle joint. The X-rays will be used to measure angles and implants needed for orthopaedic surgery repair.

What happens after diagnosis is made ?

Initially, if just a partial tear is suspected, pain relief and anti-inflammatories are prescribed, with instructions for strict rest and exercise restrictions.

Once the cruciate ligament is ruptured the stifle joint is unstable. The meniscal cartilage that cushions the bones start to wear abnormally and this leads to degenerative joint changes, which is arthritis. Bone spurs (osteophytes) develop which cause chronic pain and reduce the range of movement the joint has.

This irreversible process can be stopped or slowed by surgical correction. These osteophyte degenerative changes can be apparent as early as one to three weeks after rupture, and will have a faster onset in larger, heavier breeds.

Within human medicine there is controversy over surgery, however, there is strong evidence that supports surgery in dogs being more favourable and beneficial.

There are three known surgery techniques for treating cranial cruciate rupture. The method used will be dependent on patient suitability and the orthopaedic surgeon doing the procedure. They will discuss with you the technique, recovery time, rehabilitation needed and risks of each procedure to help determine which is best suited to your pet.

The three techniques are: extracapsular repair, tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA).

Post operative expectations

After surgery, your pet will have strict exercise and rehabilitation instructions which need to be followed to ensure a smooth recovery. Your vet will discuss this in depth with you prior to discharge.

Expect your pet to be prescribed pain relief after surgery, and you’ll be instructed to confine them to reduce exertion (expect crate rest). Other medications such as oral glucosamine supplementation, and Synovan or Pentosan injections can help with cartilage repair, joint inflammation and joint fluid (synovial fluid) lubrication within the joint space. Generally, depending on which surgery technique is used, recovery times expected are between eight and 12 weeks post operatively.

Overweight dogs have an increased risk for arthritis and for cruciate rupture. If your pet is on the heavier side, a weight management programme can reduce the risk of arthritis and potential rupture of the opposite cruciate ligament.

Professional rehabilitation and physical therapy post surgery is a great way to aid your pet’s recovery. Some clinics will have hydrotherapy, or acupuncture, which are great post operative therapies. Your veterinarian will also give you a list of at-home exercises to help aid your pet’s recovery.

This article was written by Dr Kerri from


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