A vet bandages a dog's front leg.

Ruptured Cranial Cruciate Ligament (ACL) in Dogs

Overview of Ruptured Cranial Cruciate Ligament in Dogs

The cranial cruciate ligament, also referred to as anterior cruciate ligament or ACL, is located within the stifle (knee) joint and acts to stabilize the femur on the tibia. The ligament can be torn as a result of an acute traumatic event or more commonly it ruptures due to a slow progressive breakdown of the ligament.

When the tear is sudden and complete, lameness may be severe and such that your dog refuses to bear weight on the leg. When the tear is partial or incomplete an intermittent lameness that is more noticeable after heavy exercise may be seen. Your dog may seem more lame on some days than others.

In large dogs (greater than 30 pounds), the joint usually becomes arthritic and the joint thickens if surgical stabilization is not performed.

What to Watch For

Symptoms of Ruptured ACL in dogs include:

Diagnosis of Ruptured Cranial Cruciate Ligament in Dogs

The diagnosis is generally made by your veterinarian during the physical examination. Your veterinarian will want to know whether the lameness occurred gradually or suddenly, whether it is intermittent or continuous, and whether or not it is exacerbated by exercise.

Your dog will be observed at rest, walking and trotting. The leg will be palpated (felt) and the knee joint will be evaluated for swelling, evidence of pain, thickening, “clicking” on flexion and extension, and the range of motion (flexion and extension) determined.

Specific tests to evaluate the integrity of the cranial cruciate ligament include a cranial drawer test or a tibial compression test, which are used to determine if there is increased movement in the joint. The movement in one knee will be compared to the movement in the other rear limb.

Both stifle joints may be radiographed for comparison. X-rays may show joint swelling and various degrees of arthritis depending on the length of time the rupture has been present.

Treatment of Ruptured Cranial Cruciate Ligament in Dogs

Home Care and Prevention

Depending on the type of surgery that has been performed, your dog may go home with a soft padded bandage on the leg. If this is the case, check the toes daily for swelling or discomfort and keep the bandage clean and dry by putting a plastic bag over the foot when your dog goes outside to go to the bathroom.

If there is no bandage, the incision can be monitored for swelling, redness or discharge.

Stitches or staples should be removed at 10-14 days.

Regardless of the surgical technique used, your dog should be kept quiet for a period of six weeks, with no jumping on or off furniture. Don’t let your pet go up or down stairs if possible and allow only short leash walks to go to the bathroom.

Anti-inflammatory medication may be prescribed for the first week following surgery.

After six weeks you can begin to increase your dog’s exercise slowly and gradually until he returns to his normal levels approximately sixteen weeks after surgery.

In cases of acute cruciate ligament rupture there is nothing to prevent the injury from occurring. When the problem is intermittent and more chronic, prompt veterinary attention and treatment can reduce the amount of arthritic damage that will occur within the knee joint.

In-depth Information on Canine Ruptured Cranial Cruciate Ligament

Sudden onset hind leg lameness following cruciate ligament injury can be so severe as to produce lameness as profound as a long bone fracture. Unlike a fracture, swelling and pain are restricted to the stifle (knee) joint.

Other Causes of Hind Limb Lameness

In-depth Information on Diagnosis

It is important to discuss the history of the lameness, whether the problem was sudden in onset or appeared gradually over a period of months, improving with rest but always getting worse after exercise.

In-depth Information on Treatment

The majority of small dogs (86 percent in one study) did not require surgical intervention and did just as well with strict rest, weight loss and the use of short courses of anti-inflammatory medication. Should the lameness persist, then surgery is recommended. Restriction like this for 6-8 weeks will not detrimentally affect the surgical outcome, should it prove necessary later on.

Surgical Options For Treating Torn ACL’s in Dogs

Broadly speaking there are two categories of surgery known as intracapsular techniques, where an effort is made to replace the damaged cruciate ligament with a natural or synthetic replacement, or extracapsular techniques, which aim to restore the function of the cruciate rather than the ligament that was damaged. Over recent years, intracapsular techniques have become less popular. The following are major extracapsular techniques:

Follow-up Care for Dogs with Torn ACL’s

Following surgery, many dogs remain hospitalized overnight in order to be monitored for full anesthetic recovery and to receive appropriate analgesic medication.

The use of a soft padded bandage to cover the leg after the procedure varies with the surgery and the surgeon. The bandage offers some comfort and reduces some of the postoperative swelling but, in fact, offers minimal support. If a bandage is used it should be kept clean and dry by placing a plastic bag over the foot every time the dog goes outside. The toes should be felt at the bottom of the bandage and assessed for swelling, sweating or pain, at least once a day.

If there is no bandage present, the incision can be assessed for swelling redness or discharge. In the case of a TPLO surgery, there is also a small incision lower down the leg, toward the ankle. Some swelling around the ankle may occur. This is not uncommon and usually responds well and quickly to the use of hot compresses.

Stiches or staples should be removed in 10-14 days.

Strict rest is essential for the first six weeks following surgery which means, ideally, no going up or down stairs, no jumping on or off furniture, avoiding slippery surfaces and walks, and going out on a leash for bathroom purposes only. With the TPLO surgery in particular, many dogs can recover extremely quickly. Owners should beware of this “false sense of security” afforded by dogs doing very well very early following surgery, and continue the rest for the full six week period.

Anti-inflammatory medication can be helpful for the first week following surgery, such as deracoxib, aspirin or carprofen (Rimadyl®).

After six weeks of rest, a slow, gradual increase in exercise should begin, with slow leash walks getting longer and longer in small increments such that over a further six weeks your dog is going on thirty minute walks, with short periods off the leash with far greater freedom around the house, including the use of stairs. By sixteen weeks after surgery, there should be no restriction on exercise.

Prognosis For Dogs with Ruptured ACL Ligaments

Early diagnosis and treatment an help minimize the progression of arthritis in the knee joint so the sooner you make a decision on treatment the better for your dog.

It is estimated that about half (30% to 50%) of dogs that tear one ACL will tear the opposite ACL with 2 years. For dogs that are overweight – there is a 25% risk of rupture of the opposite leg in the 3 – 6 months after the leg ACL due to increased stress on the other leg.

The American College of Veterinary Surgeons documents that 40-60% of dogs with will develop a similar problem in the other knee at some “future time”. It is common for some dogs to have a partial tear in one knee that eventually develops into a full tear.

Prevention of Ruptured ACL Ligaments in Dogs

Obesity can be a risk factor for tearing the ACL in dogs. A regular exercise routine and keeping your dog at healthy weight and help minimize the risk.