Cruciate ligament injuries in dogs

28 Aug 2019

Rupture of the anterior cruciate ligament (ACL) in the dog’s knee is one of the most common orthopaedic injuries seen in veterinary practice. This injury is painful and can lead to a reduction in the function of the joint and debilitating arthritis. It can greatly affect your dog’s quality of life if it is not treated correctly.

What is a cruciate ligament?

The cruciate ligaments are positioned in the knee. These fibrous ligaments cross over from the femur to the tibia (the bones above and below the knee joint). The anterior cruciate ligament inserts towards the front of the tibia and helps stop the tibia from moving too far forward. It also stops the knee from extending too far and reduces rotation of the tibia.

There are two types of rupture of the canine cruciate ligament. One can occur slowly over time, also known as a chronic or degenerative form of the disease. The other is an acute or sudden traumatic rupture of the ligament.

Chronic anterior cruciate ligament rupture

This form of the disease is more common but not completely understood. It is thought that over time there is a degeneration of the fibres of the ligament often through a number of small, repetitive tears. This creates a cycle of inflammation and subsequent arthritic change which presents as a mild, intermittent lameness. The condition gradually gets worse until eventually complete rupture of the ligament occurs.

Acute or traumatic rupture of the anterior cruciate ligament

Complete and sudden rupture of the ligament occurs when there is an excessive twisting of the knee joint. This can be when a dog suddenly jumps off a height such as a brick wall or after jumping out of the car.

Another common presentation is a dog with a ruptured cruciate ligament after turning quickly when leaping up to grab a ball at the park. This is very painful for dogs and they won't be able to stand on the injured hind leg or may only ‘toe touch’ their hind leg to the ground.

Signs of a cruciate ligament rupture or tear in dogs:

  • Sudden lameness (limping) in a hindlimb
  • Non-weight bearing lameness of a hindlimb
  • Toe touching a hind limb to the ground or at rest (just touching toe to the ground)
  • Intermittent lameness in a hind limb
  • Less active than usual and reluctance to exercise due to the pain
  • Loss of muscle on the hindlimb (muscle atrophy)

Diagnosis of cruciate rupture in dogs

Any dog with hindlimb lameness should be checked for cruciate ligament disease by a veterinarian. If a cruciate rupture in a dog is suspected, examination under sedation or general anaesthetic will be necessary to enable correct diagnosis.

Your vet will look for evidence of instability by feeling for any inappropriate movement of the knee joint. Your dog needs to be asleep and the joint very relaxed for a thorough evaluation. Your vet will also take radiographs (x-rays) to identify evidence of swelling around the joint or any arthritic changes that may indicate chronic disease.

Treatment of canine cruciate rupture

Surgery to stabilise the joint is the best option for treatment. Canine ACL surgery involves removing the fragmented ligament and stabilising the joint. The exact technique used will depend on the size of the dog and the dog’s age and condition, as well as the health of other joints such as the hips.

Small dogs may respond to conservative treatment (rest and non-steroidal anti-inflammatory medication) but due to instability in the joint, these dogs will likely develop arthritis so these patients must be carefully managed and treated appropriately to manage pain and ensure a good quality of life.

Your vet will be able to give you more information on the most suitable type of treatment for your dog.

How long does it take for a dog to recover from knee surgery?

Dogs need to have their activity restricted for eight to twelve weeks after the surgery. Careful rehabilitation is essential as is weight management. All patients benefit from physical therapy after the surgery to help speed up recovery and reduce the risk of complications.

Specific diets that are suitable for joint disease should be considered as these can help prevent arthritis. Management of arthritis with arthritis injections and nutriceuticals will also be needed.

Your veterinarian will be able to answer any specific questions you have about rehabilitation following cruciate ligament surgery.

You should always speak to your vet for advice on cruciate ligament disease or if you are worried about your pet.

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