Torn ACL in Dogs: Understanding Cruciate Ligament Injuries

Has your dog suddenly started limping after playing at the dog park? Or maybe they have been limping off and on for a while and you are concerned. It could be due to a torn cruciate ligament (also known as an ACL or CCL). ACL tears don’t just impact football players, or even humans in general. They can happen to any dog, especially young, healthy, and large-breed dogs.

Read on to understand how a torn ACL in dogs can happen, is diagnosed, and is treated.

Do Dogs Have An ACL?

First things first: is there a difference between an ACL and a CCL?

ACL stands for anterior cruciate ligament, and while in veterinary medicine, we typically use the term CCL (cranial cruciate ligament), the terms and function are similar. 

The cranial cruciate ligament is one of the ligaments (a fibrous piece of connective tissue) in a dog’s knee (stifle) that connects the thigh bone (femur) to the shin bone (tibia). Cranial means the front of the knee, and cruciate refers to the fact that it is one of two ligaments that forms a cross in the knee. The CCL acts to stabilize the knee joint by limiting forward movement of the tibia in relation to the femur.

Causes of Cruciate Ligament Tears in Dogs

The cranial cruciate ligament is known to rupture due to sudden trauma or through degeneration over time. Owners who witness a sudden presentation of limping caused by a CCL tear usually report that their dog was running and jumping in the backyard or dog park, or perhaps they were playing frisbee or flyball. Any activity that causes a fast, twisting motion of the knee (including high-impact sport) could potentially result in a torn cruciate ligament. 

The most common dogs seen in the veterinary clinic with torn CCLs are young, active, large-breed dogs. Another risk factor includes being overweight, and it has also been shown that genetics plays a part in the strength of the cruciate ligament. Some breeds are more prone to tears, such as German Shepherds, Labrador Retrievers, Newfoundlands, Rottweilers, and Staffordshire Terriers.

Symptoms of CCL Tears in Dogs

Pet parents may be concerned that their pet has a torn CCL if they see any of the following signs:

• Limping, including not wanting to put weight on the affected back leg
• Vocalizing, including crying or whining
• Trembling and sensitivity to touch of the leg
• Unwillingness to rise from a sitting position
• Difficulty climbing stairs
• Sitting with the affected limb out to the side of the body
• Decreased muscle mass of the bad leg
• Variable lameness with exercise that may resolve with rest
• Increased thickness of the joint capsule, especially on the inside of the leg

Diagnosing Cruciate Ligament Injuries in Dogs

Properly diagnosing a torn cruciate ligament in dogs requires a trip to your veterinarian, where they will: 

• Get a history of your pet’s lameness 
• Perform a physical exam
• Touch and feel (palpate) the leg for instability, pain, and abnormal popping of the joint. 

Your veterinarian will also perform one or two tests: a cranial drawer test or a tibial compression test. Both of these tests check for abnormal movement of the tibia forward in relation to the femur. It may be very difficult to perform this test on an animal who’s awake and in pain, so sedation may be necessary to adequately diagnose your pet’s lameness. 

Your veterinarian will also want to perform X-rays of both rear limbs. They’ll look for signs of swelling in the knee that is suggestive of a CCL tear. X-rays will also help to rule out other causes of lameness, including infection, cancer, arthritis, and patellar luxation (when the knee is not in the proper location). In some cases, your veterinary hospital may recommend an MRI or joint taps (collecting fluid from the joint).

How to Treat Torn Cruciate Ligaments in Dogs

Cruciate Ligament Surgery for Dogs

Surgery is generally recommended for your dog to regain optimal function of the knee. TPLO surgery is a common choice for this type of injury, but there are other surgical options as well. The best procedure for your pet depends on multiple factors, including the type of dog, the surgeon’s preference, and any compounding conditions (like a secondary meniscal tear). 

The purpose of the surgical correction is to recreate the function of the cranial cruciate ligament and to improve stability of the joint. Even though some arthritis will occur regardless of the treatment method, less arthritic changes will occur following surgical correction. All knee surgeries are done under general anesthesia, where your dog is asleep and given pain medication.

Surgery on the knee is more complicated than an average surgical procedure (like a spay or neuter) and needs to be performed by an experienced veterinary surgeon. Many veterinarians don’t feel comfortable performing this surgery in their practice due to the complexity and specialized equipment necessary. 

Non-Surgical Treatment for a CCL Tear

There are some non-surgical options out there, including pain medication and leg splints; however, they tend to be less successful than surgical intervention. This is because these treatments do not resolve the underlying instability present in the joint, and this instability causes more damage and arthritis over time. You may notice that lameness will initially improve, but the animal will never return to their pre-injury activity without recurring lameness.

Cost to Treat CCL Tears in Dogs

The cost of treatment can range anywhere from $2,000 all the way up to $8,000 or more. This number depends on the type of surgery performed, the size of the dog, the severity of the injury, and where the surgery is performed.

Dog CCL Tear Recovery

Recovery is just as crucial as the surgery itself. Your veterinary hospital will give you anti-inflammatory pain medication and strict post-operative instructions, including physical therapy and exercise restrictions that are necessary to improve future weight-bearing and usage of the limb. 

It’s very important to follow these exercise restrictions and to only allow your pet to go outside on a leash to prevent failure of the surgical correction and further injury. Typically recommended to start 24 to 48 hours post-op, physical rehab can range from icing and massage with passive range of motion exercises at home, to laser therapy and underwater treadmill. Post-op healing typically takes six to eight weeks before restrictions can be lifted.

How to Prevent Cruciate Ligament Injuries in Dogs

This is definitely a case where prevention is the best medicine. No one wants to put their beloved pet through this type of surgery and recovery, especially since research shows that approximately half of dogs with a cranial cruciate rupture end up experiencing a similar issue in the other knee. [1]

The best prevention for a cranial cruciate tear is to keep your pup at a healthy weight. If they are overweight, please speak with your veterinarian about ways to decrease their weight. Keeping your pet fit with regular walks and a nutritious diet is also important.

Reference

1. Harasen G. Latest research in orthopedics – more highlights from the 35th Annual meeting of the Veterinary Orthopedic Society. Can Vet J. 2009 Feb;50(2):194. PMID: 19412401; PMCID: PMC2629425.