ACL Tear and Injuries: Why is my dog limping?

If your dog is suddenly limping or develops a limp over time, it is almost always a sign of pain. The most common causes of limping are muscle injury, ligament disease, fractures, and osteoarthritis. So, if your dog is limping, we recommend seeing a veterinarian to determine the exact cause of pain and lameness.

Today, we will talk about one of the most common causes of limping in dogs: a torn cruciate ligament, also known as an ACL tear in humans.

What is the cranial cruciate ligament?

The cranial cruciate ligament in dogs is known as the anterior cruciate ligament or ACL in humans. The cranial cruciate ligament (ACL) is one of many ligaments in the dog’s knee, connecting the femur (thigh bone) to the tibia (shin bone) in their back legs. It has many functions, including preventing the thigh bone from sliding too far forward compared to the shin bone.


What are signs of ACL rupture?

The signs will vary depending on the how severe the ligament rupture is and when the injury occured.

Signs of acute rupture of the ACL ligament:

  • Non-weight bearing or tip-toeing on their hindlimb
  • Abnormal posture
  • Swelling and warmth in the knee
  • Hindlimb sticking out to one side when sitting down
  • Reluctance to rise, jump or walk
  • Partial rupture of the ligament is more subtle and can progress into complete ligament rupture

Signs of chronic rupture of the cranial cruciate ligament:

  • Lameness that has been persisting despite rest
  • Slow, stiff gait
  • Reluctance to rise, jump or walk
  • Thickened tissue around the knee
  • Abnormal posture

How is an ACL rupture diagnosed?

The diagnosis of an ACL rupture is based on clinical signs, positive “cranial drawer sign”, and X-rays findings.

The cranial drawer motion can be performed when your dog is lying down on their side. Your vet will examine the shin bone and manipulate it gently to check if it moves forward when compared to the thigh bone. It is necessary to repeat this test under general anaesthetic because most dogs are usually too painful and tense in the consult room for it to be performed correctly.

Next, X-rays of the knee will need to be performed under general anaesthetic. X-rays can show evidence of ligament rupture, swelling in the joint, and evidence of arthritis. It can also indicate other potential causes of hindlimb lameness.

It is absolutely necessary for the X-rays to be taken under general anaesthetic due to a few reasons:

  • A dog in pain will not be able to bend their leg accordingly
  • Precise X-rays are needed – this is required to plan for their potential knee surgery. These X-rays cannot be taken if the dog is moving around.

Why does the ACL rupture?

The rupture of the ACL ligament is due the ligament weakening over time. Factors that may play a role include abnormal hindlimb conformation, genetics, and obesity. The weak ligament is then ruptured following running or jumping.

Certain breeds are predisposes to an ACL ligament rupture, but any breed can be affected. However, we see ACL injury most commonly in:

  • Labrador Retriever
  • Golden Retriever
  • Rottweiler
  • German Shepherd
  • Bernese Mountain Dog
  • Mastiff
  • Saint Bernard
  • French Bulldog

What is the treatment for ACL rupture?

A specialist surgery is the recommended treatment for cranial cruciate ligament ruptures in dogs.

There are three different types of surgical techniques available.

  1. TPLO
  2. TTA
  3. Extracapsular repair

TPLO is the most commonly recommended technique by orthopedic specialist surgeons due to the high success rate of this surgical technique.

If you would like to see a model of the TPLO surgical technique, watch this video:

These are x-rays of a patient’s knee who had TPLO surgery at My Vet Animal Hospital:

What is involved in the recovery period for surgery?

Your vet will guide you through a comprehensive schedule – depending on which surgical technique has been used.

Here at My Vet, all our patients are checked are four times in the first week to ensure we have close monitoring of how your furbaby is doing after surgery. These checks are important as it allows us to ensure a smooth transition following the surgery and general anaesthetic. Your furbaby will have a day stay with us the day following surgery to give them intravenous pain relief as a CRI (constant rate infusion). This means they will have adequate pain relief and important rest to recover from their surgery. Regular check ups will also allow us to closely monitor the surgery site and your furbaby to make sure they are recovering as expected.

Weekly check ups are also performed here at My Vet thereafter until week 6. 

As a quick overview, your dog will need:

  • Crate restriction with soft bedding
  • Exercise restriction
  • Daily medication – pain relief/anti-inflammatory and antibiotics
  • Daily arthritis supplementation
  • Weekly vet checks for the first 6 weeks to ensure the wound is healing well
  • Follow up X-rays in 6-8 weeks post surgery
  • Physiotherapy
  • Weekly arthritis injections (Zydax) for 4 weeks. This is to be repeated every 6 months
  • Dietary changes

Your vet will tailor your dog’s post-op care schedule according to the surgery that was performed.

What are the complications associated with surgery?

Complication rates are very rare with experienced specialist orthopaedic surgeons. We always recommend choosing an orthopedic specialist to perform this procedure.

Some of the common surgical complications may include:

  • Infection
  • Implant rejection
  • Implant problems if your dog is not rested properly in the first crucial 6 weeks after surgery

It is important to note that up to 50% of dogs who rupture their ACL ligament will tear the other side within 2 years of each other.

What happens if I don’t elect surgery?

Once the cruciate ligament ruptures, it cannot repair itself.

If left untreated, it will cause:

  • Chronic instability in the knee joint
  • Chronic pain and inflammation in the hindlimb
  • Further damage to supporting structures in the knee joint, especially the medial meniscus (fibrocartilage band in the knee joint)
  • Irreversible damage and arthritis
  • Loss of muscle in hindlimb
  • Reluctance to go on walks or runs
  • Poor quality of life

What is the prognosis?

Prognosis is very good with surgery to repair ACL ligament ruptures in dogs. Over 95% of dogs with TPLO or TTA surgery will return to 95-100% normal function. After surgery, your dog will need plenty of rest and controlled exercise for the first 6-8 weeks to ensure a good recovery.

How much is surgery?

The cost will be provided as an all-inclusive package so there will be no hidden costs. The cost includes:

  • Surgery performed by a Specialist Surgery Veterinarian
  • General anaesthetic and drugs
  • Hospitalisation
  • Anaesthetic monitoring by a qualified and experienced Veterinary Nurse
  • Post operative check-ups
  • Course of Arthritis injections (4 weekly injections)
  • Pain relief and anti-inflammatory medication
  • Antibiotic medication
  • Arthritis supplements

In summary…

At My Vet Animal Hospital, we are focused on providing the highest quality care to our patients. We work closely with orthopaedic surgeons who will perform the surgical procedure in the comfort of our vet hospital (your dog will be happier with people that he/she knows too!). Many pet owners also prefer this as it is closer to their homes which makes follow-up appointments easier and less stressful for their dogs.

We understand that orthopaedic surgery can be a difficult time, both emotionally and financially. This is why we take our time to explain every step to you and see you regularly after surgery to ensure everything is going well. You will be provided with in-depth handouts outlining everything you need to prepare for the surgery, organise treatment at our clinic and facilitate weekly check-ups to ensure your pet is recovering well after surgery.

Ready for an appointment?

Our team is here to answer your questions and get an appointment scheduled for you.

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