Help! My dog is limping – Could it be a torn ligament?
This guide is a good starting place for anyone looking for more information on dog knee problems, specifically cruciate ligament injury in dogs. This article will give an overview of dog knee injuries covering everything from symptoms to recovery.
What is a Cruciate Ligament Injury?
An injury to the CCL (also known as the cranial cruciate ligament and sometimes called the ACL) can cause lameness in dogs, and is one of the most common causes of rear leg lameness. The function of the cruciate ligament in dogs is to stop the femur (large bone at the top of the leg, above knee) and tibia (smaller bone at bottom of leg, below knee) from rubbing against one another. When the cranial cruciate ligament is torn or ruptured the leg loses stability because these bones are now free to move back and forth on top of one another, causing friction, inflammation, possible meniscal injury and eventually arthritis.
During activities with a healthy dog ACL ligament there will be tension on the ligament, preventing the femur from pressing into the tibia, creating a sliding motion for fluid movement. If your dog is walking or running with a cruciate ligament tear there will be no tension on the CCL, allowing the bones to unnaturally move together, causing pain, lameness and an aversion to using the leg. The best way to think of this would be to envision the ligament like a rubber band, but instead of holding the bones together, the rubber band is in place to prevent the bones from coming into contact. When the rubber band is snapped, there is no longer a gliding joint in the knee and there is contact between the bones.
Acute vs. Chronic Causes of Cruciate Ligament Injury
Acute injury is generally associated with trauma. If the CCL (also referred to as ACL because of it’s similar function to the human ACL) is injured acutely it will most often be due to improper rotation of the knee and hyper extension. This can occur in many different ways such as a dog taking a misstep off a curb, stepping into a divot, jumping or becoming stuck, using a jerking motion to free him/herself.
Chronic injury of the canine ACL is generally associated with disease, age related degenerative changes of the ligament, excess weight (obesity) and conformation of the knee joint (certain large breed dogs are more prone to these types of injuries due to the way their back legs are formed). In the case of chronic injury of the cruciate ligament, there is very little that can be done to prevent the injury from taking place.
Small and large dogs fair differently with the same type of ACL injury. Studies have shown that dogs weighing less than about 25 pounds can experience a full recovery from ligament damage without surgery. This is not true in dogs above the 25 pound threshold. While dogs over 25 pounds may appear to be improving with conservative methods, these larger dogs rarely return to their full function without any issue. This is not to say that there has never been a case of a medium to large sized dog recovering from a torn CCL with only conservative management, but does demonstrate that smaller dogs have an easier time fully recovering using the conservative approaches.
Symtoms of a torn, ruptured or injured CCL will vary from dog to dog, and depending on whether the injury was acute or chronic in nature. Some dogs with a fully torn cruciate may only exhibit mild lameness, while others with a tear may not bear any weight on the leg at all. This again varies based on the type of dog, their size and whether other structures within the knee (particularly the meniscus) were also damaged. Below are some of the most common symptoms associated with a dog knee ligament injury.
Symptoms of a Dog ACL Tear:
1. Decreased range of motion.
2. Hind leg extended straight when sitting down (this is known as the sit sign).
3. Crackling noise of bones rubbing against each other – the medical term for this is Crepitus.
4. Dog exhibits signs of pain when knee (stifle) joint is touched.
5. Exercise intolerance.
6. Limited range of motion or mobility.
7. Stiffness, limping or unwillingness to use the leg after exercise.
8. Knee joint is swollen and/or hot to the touch.
9. Thick, tight, hard and/or firm feel to knee.
10. When standing will only place weight on the toe instead of using entire foot (called toe-touching). An early sign of toe-touching is to only have weight on one side of the body when standing.
There are other conditions with symptoms similar to a dog ACL injury such as: arthritis, knee sprain, meniscal injury, hip dysplasia, patellar fracture, patellar luxation, myelopathies, lyme disease and others. Please schedule an appointment with your vet if your dog shows any of the CCL tear symptoms listed above.
What if my dog’s CCL is never repaired?
This, again, depends on their size, breed and a number of other factors. Some dogs without a CCL may do just fine, while others may use the ability to use their leg. One truth for any dog without a supporting knee ligament is the fact that they will be more succeptible to injuring other structures within the knee, particularly the meniscus. The role of the mensicus in the knee is to act as a cushion, and absorb shocks. Damage to the meniscus is serious and typically leads to arthritic change and lameness.
What to Expect During Your First Veterinary Visit for a Suspected CCL Injury
Consultation and Review of Symptoms
Your veterinarian will review your dog’s symptoms and time of onset. Going through a detailed history will allow your vet to determine if conditions with similar symptoms may be ruled out at this time.
Your veterinarian will want to watch your dog walk and run to see how they are balancing their weight and using the affected leg.
Palpation of the Joint
Your veterinarian will touch your dog’s knee to assess the joint looking for signs of:
- Swelling or Inflammation
- Loss of Muscle Tone
- Pain or Soreness
- Range of Motion
- Popping of the Joint
- Fluid Accumulation
Drawer Sign Test
During the drawer test the veterinarian with stabilize your dog’s femur with one hand while manipulating the tibia with the other. If the tibia moves forward, known as a positive drawer because of the way the bone moves similar to a drawer being opened, the ligament is ruptured. A negative drawer sign does not necessarily mean your canine does not have a cranial cruciate injury, and false negatives can happen if your pet is tense, if the injury is old and if there is arthritis.
Tibial Compression Exam
Another test, similar to the eliciting the drawer sign, is the tibial compression test. During this exam your veterinary physician will stabilize the dog’s femur with one hand, while flexing the ankle with the other. In dogs with a ruptured cranial cruciate ligament, the tibia will display forward motion upon flexion of the ankle joint. Again, a negative tibial compression exam does not rule out a cruciate ligament injury, and many factors can contribute to a false negative result.
How to Test a Dog for a Knee Ligament Injury
X-Rays for CCL Injuries
Radiographs are usually taken, not to diagnose a cruciate ligament injury (soft tissue damage is not clearly visible on x-ray), but to rule out other diseases such as cancer and hip dysplasia. An xray will confirm the presence of fluid in the joint as well as arthritis, which will help to confirm the diagnosis of a cruciate ligament injury.
Ultrasound for CCL Injuries
Ultrasound may be used to positively diagnose a CCL injury. Unfortunately a minority of medical clinics are equipped to do ultrasound, and many veterinarians rely on the results of the consultation with you, physical exam and ruling out any other conditions by x-ray to make the diagnosis of a CCL injury.
My Dog Has Received a Positive Diagnosis of a CCL Injury – What Are My Treatment Options?
There are two major avenues for treating a dog knee ligament injury – conservative management or dog knee surgery.
What Is Conservative Management?
Conservative management is a non-surgical option for treating cranial cruciate ligament (CCL) injuries in dogs. Depending on the size of your dog, the severity of the injury, presence of other damage (particularly to the meniscus – remember, this is the part of the knee that acts as a shock absorber) and the duration of time since the onset CM may be a good option for your dog. As mentioned above, dogs weighing less than 25 pounds tend to have better outcomes using conservative techniques than larger dogs.
A variety of techniques can be used if you choose Conservative Management (CM) for your pet.
Conservative Management Includes:
“Standard” Conservative Management
- Rest – Your dog should remain inactive during the recovery period, abstaining from rough play, prolonged exercise or any movement that may cause any pressure or unwanted movement within the knee joint.
- Weight Control (and reduction if necessary) – One way to reduce stress on the joint is to keep your dog’s weight under control, and if possible, underweight is better during the recovery process.
- Anti Inflammatory Medications – There are a number of Holistic (ex – Yucca Root) and Prescription (ex – Rimadyl) medications available that can help to make your pet more comfortable as the knee heals.
“Optional” Conservative Management
- Dog Knee Brace – There are a variety of dog knee braces available including the orthopets canine stifle brace and atrac dynamic brace.
- Veterinary Acupuncture – Acupuncture for dogs is available, and can help to de-stress your pet as their body heals.
- Veterinary Chiropractic - A chiropractor can work with your dog to make sure your pet is free from any subluxations or other blockages.
- Physical Therapy for Dogs – Working with a certified canine physical therapist can help to ensure your dog maintains muscle tone and range of motion in the leg following their injury.
What Are The Different Types of Surgery for Dog ACL Injuries?
Dog Knee Surgery Options:
TPLO Surgery (tibial plateau leveling osteotomy)
This surgery adjusts the slope of the tibial plateau (preventing unwanted forward motion) by cutting and rotating the top of the tibia, and keeping it in position with a bone plate (which can be removed after healing).
TTA Surgery (tibial tuberosity advancement)
The TTA surgery also focuses on changing the angles of the bones within the knee joint. In a TTA the tibia is cut and moved forward to create stability. The new position of the bone is held into place with a bone plate (which can be removed after healing).
TTO Surgery (triple tibial osteotomy)
The TTO is a combintation of the TPLO and TTA techniques. It moves the tibial crest forward, as a TTA does, and also adjusts the tibial plateau to 90 degrees, as the TPLO does.
Tightrope CCL is an extra capsular technique using the lateral suture stabilization (LSS) procedure in conjunction with a material called FiberTape to provide bone to bone stabilization.
Extra Capsular Suture (traditional repair, extracapsular imbrication)
This is referred to as a traditional repair because this was once the conventional treatment for CCL tears. The extra capsular suture uses a strong leader line suture in a figure eight pattern around the knee to provide stability and keep the knee in a normal position.
Fibular Head Transposition (fibular head transfer)
The fibular head transfer surgery utilizes another ligament in the knee, the lateral collateral ligament, to take the place of the CCL. In this surgery the fibula is rotated so that the lateral collateral ligament can perform the function of the CCL.
Dog CCL Surgery Recovery
Depending on where the ligament surgery was performed, your dog may stay overnight to be monitored and receive pain medications following the procedure. TPLO surgery recovery can be different from TTA surgery recovery, so it’s important to follow the recommendations of your vet during the post operative period. Your dog’s sutures will be removed within a week or two of the procedure, and follow up appointments are typically done at 2 weeks, 4 weeks, 8 weeks and 12 weeks. Again, depending on the type of surgery done, radiographs may be done during these follow up appointments.
During the 6-14 week period following surgery it is very important to severely limit your pet’s activities. For approximately three months following dog knee ligament surgery your pet should be confined to a crate, small room or enclosed area when you are not able to be with your pet. You will probably want to make use of a dog cone collar – Elizabethan collars or Pro collars are my favorite. Make sure to post operative doggy proof your house and make sure they have no opportunity to slip, slide, jump up onto furniture, climb up stairs or engage in any activity that may damage the healing knee.
While outside you should accompany your dog for bathroom breaks, and they should always be controlled on a leash – you never know when a post operative dog may get the urge to chase a squirrel! You may increase the length of walks during the recovery period under the recommendation of your veterinarian and judging by how well your dog is recovering. I strongly recommend not letting your dog off leash at all during the first few months following surgery just to be on the safe side. Your veterinarian will most likely encourage you to have your pet use the injured limb immediately following surgery, but do not overdo it. Physical therapy during this time can also be very beneficial, and swimming is a great way to ensure your dog gets to use their leg (helping to maintain strength and muscle mass) without engaging in any activities that may be harmful to the knee.