What is the ACL in Dogs?
The anterior cruciate ligament (ACL) is one of the most important ligaments located inside the knee joint of dogs. It is a band of connective tissue that connects the femur to the tibia and helps provide stability to the knee joint (Source).
The ACL prevents excessive forward movement of the tibia in relation to the femur as well as over-rotation and hyperextension of the knee. It serves many important functions including shock absorption, proprioception, and load bearing (Source). When the ACL tears, it can lead to painful arthritis and joint instability.
The ACL is located within the knee (stifle) joint in the hind legs. The ligament courses through the center of the joint, crossed over with the posterior cruciate ligament (PCL). ACL injury is common in dogs, especially larger breeds, and is one of the most frequent causes of hind limb lameness.
Common Causes of ACL Injuries
Anterior cruciate ligament (ACL) injuries in dogs have several common causes. Some of the most frequent reasons dogs tear their ACL include:
Sports and high-impact activities. Dogs who participate in activities with lots of jumping, cutting, and pivoting like agility, frisbee, or flyball are at higher risk for ACL tears. The constant starting, stopping, and changing directions puts strain on the knee joint.
Obesity. Carrying excess weight puts more stress on the ACL and can cause it to tear during normal activity. Obese dogs are at least 5 times more likely to rupture their ACL than dogs at an optimal weight.
Genetics. Certain breeds like Labrador Retrievers, Rottweilers, and Boxers are genetically prone to ACL injuries. Their body structure and conformation predisposes them to ACL tears.
Trauma. Direct blows to the knee, falling, getting hit by a car, or stepping in a hole can cause ACL tears in dogs. Even minor trauma in combination with other risk factors can result in rupture.
While sports and obesity are common preventable causes, genetics and accidents play a role as well. Understanding the various factors leading to ACL tears can help owners take preventative measures when possible.
Sources:
https://www.brisbanepetsurgery.com.au/blog/the-most-common-causes-of-an-anterior-cruciate-ligament-tears-in-dogs
Symptoms of an ACL Injury
The most common symptoms of an ACL injury in dogs include:
- Limping (
https://www.reedanimalhospital.com/blog/the-importance-of-treating-your-dogs-acl-tear/) – Dogs will often limp on the affected back leg and avoid bearing weight on it. - Reluctance to bear weight on the leg (https://www.webmd.com/pets/dogs/acl-injuries-in-dogs) – They will frequently hold the injured leg up when standing or sitting.
- Swelling – There may be swelling around the knee joint as fluid accumulates due to inflammation.
- Loss of range of motion – The knee joint’s normal range of flexion and extension is diminished.
Other possible symptoms include stiffness after rest or exercise, difficulty rising off the floor, and struggling to jump or go up stairs. The severity of symptoms ranges from slight limping to complete inability to bear weight depending on the ACL tear’s extent.
Diagnosing an ACL Injury
If your dog is limping or showing signs of discomfort, the first step is to take them to the veterinarian for a physical exam. The vet will manipulate your dog’s knee joint to feel for instability. They may perform specific tests such as the cranial drawer test to check for laxity in the ACL.
Your vet may also take x-rays of your dog’s knee. X-rays can help rule out issues like arthritis or fractures, but they cannot directly visualize soft tissue injuries like ACL tears. For a definitive ACL diagnosis, the vet may recommend an MRI. This imaging test can clearly show damage to the ACL and any associated meniscal tears.
ACL Surgery Options
There are three main surgical options for repairing a torn ACL in dogs:
Extracapsular Repair
Extracapsular repair, also known as lateral suture stabilization, involves tightening the joint capsule and supporting ligaments on the outside of the knee joint with sutures or an artificial ligament. This helps provide stability to the knee while the ACL heals on its own. According to BetterPet, this procedure has a lower success rate than the other options. However, it is less invasive and typically has a shorter recovery time.1
Tibial Plateau Leveling Osteotomy (TPLO)
The TPLO procedure involves cutting and rotating the top of the tibia (shin bone) to change the angle of the top of the shin bone relative to the femur (thighbone). This helps stabilize the knee joint. According to the Leighton Veterinary Clinic, this surgery is more complex but has a high success rate. However, the recovery time is longer than extracapsular repair.2
Tibial Tuberosity Advancement (TTA)
The TTA procedure advances the tibial tuberosity, which is the bump on the front of the top of the shin bone. This changes the angle between the femur and tibia to help stabilize the knee joint. TTA has a high success rate but involves meticulous measurements and placement of the implants. Recovery time is similar to TPLO.1
The ACL Surgery Recovery Process
The recovery process after ACL surgery in dogs focuses on rest, restricted activity, and physical therapy exercises. The recovery timeline usually lasts around 8-12 weeks.
For the first 4 weeks after surgery, rest and restricted activity are crucial. Your dog should be confined and prevented from running, jumping, or playing. Only short, leashed walks are permitted during this time. Per Hill’s Pet Nutrition, walking should be limited to 10-15 minutes during the initial recovery period.
Around 4-6 weeks after surgery, your vet may clear your dog to gradually return to normal activity. But strenuous exercise should still be avoided. Your vet may recommend beginning physical therapy exercises like passive range of motion to improve mobility and prevent atrophy. Exercises may involve gently bending and extending the knee joint.
At the 8-12 week mark, your dog can usually return to normal activity levels, provided the knee shows good healing. But your vet may recommend continued conditioning exercises and avoiding high-impact activities that could re-injure the knee. Complete recovery can take up to a full year.
Follow up exams with your vet are crucial to monitoring your dog’s recovery on the appropriate timeline. Be sure to avoid overdoing activity or exercise before the knee is fully healed.
Expected Mobility After 4 Weeks
It is normal for your dog to still have some degree of limping 4 weeks after ACL surgery. Even though significant healing has occurred, the affected leg is still recovering strength and range of motion during this timeframe.
According to PetMD, dogs usually take 4-6 weeks to recover from ACL surgery. While swelling should be minimal, it is common for dogs to continue having a mild limp after 4 weeks as the leg continues to heal. Your dog may walk more slowly, carefully, and have stiffness getting up.
As outlined by Licks & Sleeves, your dog should be able to comfortably walk short distances after 4 weeks. However, their gait may not be back to normal yet. Your vet will assess things like muscle loss and range of motion at the 4 week mark.
It’s important to keep doing the at-home recovery exercises recommended by your vet during weeks 4-6. Walks should be kept short and slow to avoid overexertion. With time and proper care, your dog’s limping should gradually improve in the coming weeks. But some stiffness and limitations are expected halfway through the recovery process.
Sources:
https://www.petmd.com/dog/general-health/recovery-dog-acl-surgery
https://www.licksleeve.com/blogs/news/dog-acl-surgery-recovery-week-by-week-timeline
When to Call the Vet After Surgery
Even with a successful ACL surgery, some complications can arise during the recovery process. It’s important to monitor your dog closely and contact your veterinarian if you notice any of the following:
Persistent lameness beyond 4 weeks – Some lingering stiffness and lameness is normal early in the recovery process. However, if your dog is still not bearing weight or is severely limping after 4 weeks, there may be a complication like implant failure, continued instability, or improper healing.1
Significant swelling – Mild swelling and bruising around the incision site is common after surgery. But major or increasing swelling may be a sign of infection or fluid buildup in the joint.2
Infection – Signs include drainage, redness, heat, foul odor, and fever. Infections should be treated immediately with antibiotics to prevent complications.3
Your vet will want to examine your dog and possibly take x-rays to determine the cause of any lingering or worsening symptoms post-surgery. Prompt treatment will give your dog the best chance at making a full recovery.
Caring for Your Dog After Surgery
Proper aftercare is crucial for your dog’s recovery after ACL surgery. Here are some of the main things you’ll need to do:
Medications – Your veterinarian will prescribe pain medications and anti-inflammatories to help manage your dog’s pain after surgery. Be sure to give all medications as directed. Pain management is very important, especially in the first 2 weeks after surgery.
Ice/Rest – Limiting activity and providing ample rest time is key to recovery. You’ll need to confine your dog to a crate or small space when you can’t directly supervise. Apply ice packs to the affected knee for 10-15 minutes a few times per day to reduce pain and swelling, especially in the first 2 weeks. Provide soft, padded bedding so your dog can rest comfortably.
Physical Therapy – Starting gentle range of motion and stretching exercises within the first week after surgery can help rebuild muscle and prevent scar tissue formation. Low-impact leash walks can usually start 2 weeks after surgery. More intensive physical therapy often begins around 4-6 weeks post-op. Consult your vet on the appropriate rehab timeline and exercises for your dog. Some practices provide in-house therapy programs. Physical therapy helps dogs regain strength and mobility in the affected leg over time.
Proper at-home care can make all the difference in your dog’s ACL recovery. Follow your vet’s specific instructions for medications, activity restriction, and physical therapy. Provide ample rest and supervision, especially in the initial weeks after surgery, to support the healing process. With time and patience, most dogs go on to lead active lives after ACL repair.
Long-Term Outlook After ACL Surgery
The long-term outlook for dogs after ACL surgery is generally very good if proper recovery and rehabilitation protocols are followed. With appropriate rest, restriction, and physical therapy during the recovery period, most dogs are able to regain normal function in the affected leg. It typically takes 4-6 months for the knee to fully heal after surgery.
The key to maximizing the long-term outcome is to allow adequate healing time and avoid overexertion or re-injury during recovery. Activities like running, jumping, or rough play need to be restricted for at least 8-12 weeks after surgery. Leash walks should be kept short and gradual return to normal activity over several months. Even after healing, it is recommended to avoid high-impact activities that could stress the knee joint.
Steps can also be taken to help prevent re-injury to the repaired ACL or injury to the opposite knee, as dogs have a higher likelihood of bilateral ACL tears. Maintaining a healthy weight, doing low-impact exercise, providing joint supplements, and avoiding slippery floors or activities on unstable surfaces are important preventive measures (Dog ACL Surgery Recovery: A Week by Week Timeline, 2022). With proper care and rehabilitation, most dogs go on to live active lives after ACL repair.