Introduction
ACL (anterior cruciate ligament) tears are a very common orthopedic injury in dogs. The ACL is one of the major ligaments that stabilizes the knee joint. When it ruptures, it causes the knee to become unstable and painful. ACL tears generally occur in active dogs while playing or exercising. Certain breeds like Labradors, Rottweilers, and German Shepherds are more prone to ACL tears. Dogs with ACL injuries often have symptoms like limping, holding their leg up, stiffness after resting, and swelling/pain around the knee joint. If the ACL is completely ruptured, the knee becomes very unstable. There are two main treatment options – conservative management focused on restricting activity vs. surgical repair to stabilize the knee. The treatment recommended depends on factors like the dog’s age/breed, degree of tear, and lifestyle. Many active, larger breed dogs end up needing ACL surgery. Early treatment is crucial to prevent complications like arthritis down the road.
What is the ACL
The anterior cruciate ligament (ACL) is one of the key ligaments located in a dog’s knee joint. It runs diagonally through the middle of the knee and connects the femur to the tibia. The main function of the ACL is to provide stability to the knee joint and prevent excessive forward movement of the tibia in relation to the femur. The ACL also limits internal rotation of the knee and helps control hyperextension
The ACL is located completely within the knee joint. It originates at the caudomedial aspect of the lateral femoral condyle and attaches distally on the cranial tibial plateau. It crosses the knee joint at an angle, providing rotational stability. Without the ACL, the tibia would be unstable and prone to slipping forward under the femur, especially during activities like running or jumping.
Causes of ACL Tears
There are several potential causes that can lead to ACL tears in dogs:
Genetics – Certain breeds like Labradors, Rottweilers, and Newfoundlands are genetically predisposed to ACL injuries due to anatomical factors like having steep tibial plateau angles [1]. This causes extra strain on the ACL.
Conformation – Dogs with straight hind legs are more prone to ACL tears since their legs experience torsional forces versus dogs with angulated legs. The ACL helps stabilize the knee joint, so structural leg issues increase risk [2].
Trauma/Falls – Sudden stops, jumps, or falls can cause tears by overextending the knee joint. This acute injury causes partial or complete ACL tears.
Obesity – Carrying excess weight increases stress on joints and ligaments. Obese dogs have 4x higher rates of ACL rupture according to studies [3]. Losing weight can help prevent injury.
Symptoms
Some common symptoms of an ACL tear in dogs include:
Lameness – Dogs with a torn ACL often have difficulty bearing weight on the affected leg and show obvious limping. They may hold the leg up while standing and avoid using it when walking. According to Laguna Canyon Vet, lameness is one of the most frequent symptoms of ACL injuries in dogs.
Swelling – A torn ACL can cause inflammation and swelling in and around the knee joint. Owners may notice puffiness or thickening of the knee area. Per Reed Animal Hospital, swelling of the knee is a key sign of ACL damage.
Abnormal gait – Dogs with an ACL tear tend to have an abnormal gait and very ginger use of the hind leg. Their walk may appear bowlegged or knock-kneed on the affected side. According to Reed Animal Hospital, shifting weight away from the torn ACL is common.
Reluctance to move, exercise, or play – ACL tears are very painful. Dogs often show a reluctance to move around normally, go up or down stairs, jump on furniture, exercise, or play. Per Laguna Canyon Vet, ACL injuries cause stiffness and difficulty rising after rest.
Diagnosis
Diagnosing an ACL tear starts with a physical exam by your veterinarian. They will check for signs of lameness, swelling, stiffness, muscle atrophy, and pain when manipulating the knee joint. Specific tests like the tibial thrust test, cranial drawer test, and tibial compression test can indicate laxity and instability in the knee from an ACL tear (1).
Your vet will likely take x-rays of the affected leg. X-rays allow vets to see the bones, joints, and soft tissues. They can look for any arthritic changes in the joint or bone fractures that may be causing lameness. X-rays alone can’t directly visualize a torn ACL, but can rule out other issues (2).
Your vet may perform arthrocentesis, inserting a needle into the knee joint to extract synovial fluid. Analysis of the fluid can detect inflammatory changes and rule out infections inside the joint (3).
An MRI is the most accurate way to diagnose an ACL tear since it visualizes the soft tissue structures. But MRIs are expensive and require anesthesia. They are usually reserved for complex knee injuries or if surgery is being considered.
(1) https://topdoghealth.com/library/orthopedic-condition/articles/acl-tears/
(2) https://furdunkin.com/what-you-need-to-know-about-dog-acl-tears/
(3) https://toegrips.com/torn-acl-in-dogs-diagnosis-recovery/
Conservative Treatment
Conservative treatment options focus on managing the injury and improving stability without surgery. This involves a combination of rest, anti-inflammatories, physical therapy, and weight management.
Rest is crucial, especially right after the injury occurs. Restricting activity and exercise can allow inflammation to subside and prevent further damage. Short, leashed walks are recommended to avoid too much activity. Confinement may be needed initially depending on the dog’s energy level.
Anti-inflammatory medications like NSAIDs are commonly prescribed to reduce inflammation and pain. These should be given under vet supervision. Supplements like glucosamine may also help.
Physical therapy aims to strengthen muscles around the knee and improve proprioception. This usually involves range of motion, stretching, massage, icing, and other gentle exercises. A physical therapist can create a customized program. Low-impact activities like swimming can also be beneficial.
If a dog is overweight, a weight loss plan can take pressure off the knee joint. Achieving an optimal body weight is key for recovery and preventing future injuries. A veterinarian can provide specific weight loss recommendations.
Surgery
There are two main types of surgery used to treat ACL tears in dogs: tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA) [1]. Both procedures involve altering the geometry of the stifle joint to stabilize the knee and prevent further damage to the ACL.
In a TPLO surgery, the tibial plateau angle is changed to neutralize the caudal tibial thrust that occurs with ACL deficiency [2]. This converts some of the vertical forces on the joint to horizontal forces. It requires an osteotomy (bone cut) of the tibia.
With TTA, the tibial tuberosity is cut and advanced forward using a titanium or steel implant [3]. This changes the patellar tendon angle, reducing the tibial thrust. No bones are cut, just soft tissue.
Recovery time is typically 8-12 weeks for both procedures. Strict exercise restriction is required during the initial healing phase. TTA may allow dogs to bear more weight sooner after surgery than TPLO.
The cost for ACL surgery ranges from $3,000-$5,000 per knee. TPLO is generally more expensive than TTA. Additional imaging, medications, and physical therapy can increase the total cost.
Post-Op Care
Post-operative care is crucial for a successful ACL surgery recovery. Here are some key things to focus on during this period:
Restricted Activity: It is very important to restrict your dog’s activity during the first two weeks after surgery to allow the surgical site to heal. Take your dog out on a leash only for potty breaks during this time. Do not allow running, jumping, or playing. You may need to confine your dog to a small space like a crate or pen when you cannot directly supervise them [1].
Physical Therapy: Around 2-4 weeks after surgery, your vet will likely prescribe physical therapy sessions with a canine rehabilitation specialist. These appointments will focus on range of motion exercises, strengthening, weight shifting, balance training, and other activities to help your dog regain normal function [2].
Follow-Up Exams: Your vet will want to see your dog for several follow-up appointments after surgery to check the incision site, remove sutures, and monitor recovery progress. These visits usually occur around 2 weeks, 6 weeks, 3 months, and 6 months post-op [3].
With proper post-operative care, most dogs are able to return to normal activity levels and have an excellent outcome from ACL repair surgery.
Long-Term Management
Proper long-term management after an ACL injury is crucial for your dog’s comfort and mobility. This involves modifying their exercise routine, maintaining a healthy body weight, and administering joint supplements. According to WikiHow, dogs with ACL tears should avoid high-impact activities like jumping and running. Switch to lower impact exercises like leash walks and swimming. Keeping your dog at a lean body weight will reduce stress on the joints. A dog that is overweight puts more pressure on the ACL and can cause reinjury. Talk to your vet about safe weight loss options if needed.
Joint supplements containing glucosamine, chondroitin, and omega-3 fatty acids can help lubricate and protect the joints over time. According to OrthoDog, these supplements support cartilage health and reduce inflammation. They are safe for long-term use. Work closely with your veterinarian to find the right supplementation regimen for your dog’s needs and lifestyle.
With proper long-term care, many dogs can regain good mobility and live active lives after ACL injury. Keep up with exercise modifications, weight management, and joint support supplements for optimal outcomes.
Outlook
The long-term prognosis for dogs with ACL tears depends greatly on whether they receive treatment or not. Without treatment, the prognosis is poor. The ACL is crucial for stabilizing the knee joint, so dogs with untreated ACL tears will experience progressive arthritis, instability, lameness, and pain. Their quality of life deteriorates as simple activities like walking and standing become increasingly difficult. According to long-term studies, over 90% of dogs with untreated ACL tears develop debilitating osteoarthritis within 1 year.
With proper treatment, either conservative management or surgery, the prognosis for ACL tears is good. According to the Colorado State Veterinary Hospital, 85-90% of dogs have significant improvement after ACL surgery. There are various surgical techniques, but procedures like TPLO that stabilize the knee joint tend to have excellent outcomes. In a study of TPLO surgery, 90% of dogs resumed normal activity levels and experienced greatly improved quality of life over the long term.
While ACL tears can’t be fully cured, dogs who receive treatment can regain excellent function and have a good prognosis for a high quality of life. With proper post-op care and management, most dogs with surgically treated ACL tears are able to return to normal activity levels and live an active lifestyle.