‘Tis the season for… knee injuries?

15 May

Ah, Spring. The air is warm. The grass is green. The bunnies are frolicking on the lawn. And your dog, fresh from a hard winter spent snoozing on the couch, just came up lame after chasing something cute and furry across the yard.

Cruciate Ligament tears in dogs is, unfortunately, a common injury , and one of the leading causes of hind-leg lameness. The cruciate ligament reaches from the upper legbone to the lower leg bone in the dog, and is an important factor in keeping the knee stable. When this tears, the knee joint moves around far more than it should, causing pain and leading to arthritis and dejenerative joint disease. Think football injury in people. It’s very uncomfortable for the dog.

While all breeds of dogs (and even cats, though it is uncommon) are at risk for this injury, there is a number of predisposing factors. Large breeds, especially dogs who are overweight, are at increased risk. Middle-age dogs are more likely to rupture their cruciates, and for whatever reason, spayed females are at an increased risk. There are breed factors too– Labs and Rotties are overrepresented. Pit bulls are another type of dog frequently affected. And not to leave out the little dogs, Cocker Spaniels have a higher than average occurrance of this problem. Small breed dogs with kneecaps that slip out of place (luxate) are at higher risk because there is already stress and instability in the knee joint.

But one of the biggest risk factors is Weekend Warrior Syndrome. You know the dogs I’m talking about– during the week, they spend most of their time sleeping on the couch while their family is away at work or school or evening activities. But on the weekend, everybody has time to exercise the dog, and he’s got tons of energy but maybe he isn’t as physically fit as he thinks he is. He goes tearing off after a rabbit, or maybe he’s just romping in the yard, being a dog, and bam! He is limping dramatically.

The hurty knee sit.

The hurty knee sit.

The weird thing about cruciate ligament injuries is that they can be a chronic issue. The ligament can stretch or tear just a little bit at a time, so you might notice your pooch being a little stiff for a few days, limping a little bit, and then it goes away and he’s fine. You might see him sitting funny, with one of his legs propped out to the side. He might especially have trouble after he’s been resting and still for a while. He might sometimes walk with a limp, only putting down his toes instead of his whole foot (referred to as “toe touching”) but then it goes away. And then one day he jumps out of the car or off the couch– nothing unusual at all– and he’s hurt. Because all this time, his ligament has been tearing a little bit at a time, and then all of a sudden– like an old shoestring– it finally tears the whole way through.

When this happens, especially in a big dog, the best course of action is surgical repair.

In small dogs (under 30 pounds), it is possible to get away without surgery. There is an increased risk of arthritis and chronic lameness with the non-surgical route. Strict crate rest is imperative for at least 8 weeks following injury. The dog must be leash-walked to potty and there can be no running or jumping at all. Usually pain and swelling is managed with a non-steroidal anti-inflammatory medication prescribed by your vet.

This conservative course of action can be an option in a larger dog too, especially when money is an issue or the dog is older and a couch-potato, but the outcome is generally not as good. The weight of a big dog, especially if he is overweight, just makes for a more difficult healing process and increased arthritis, and the increased work asked of the opposite leg makes it more likely to have a problem as well. Unfortunately, once a dog tears one cruciate ligament, his chance of tearing the other is 30-40%.

There are a variety of different types of surgery to repair a knee with a torn cruciate ligament. The surgeon will choose which surgery is the most appropriate based on size, weight, structure, activity level, and his own comfort with the procedure.

One of the most common surgical repairs is called an extracapsular or “fishing line” repair. In this surgery, the torn ligament is replaced by a nylon cord threaded through holes drilled in the bones to recreate a ligament. The idea is to keep the knee stable enough for long enough for the body to form scar tissue to keep the knee stable on its own. This procedure can work wonderfully for some dogs, especially smaller, less active dogs.

For larger or more athletic and active dogs, often a surgeon will look toward a surgery that changes the angles of the knee so that the bones stay where they belong.

The first of these two surgeries is called a Tibial Tuberosity Advancement (TTA). Basically, the very front of the tibial bone is cut and angled forward to change the physics of the knee, keeping the femur from sliding. This stabilizes the knee and lets the dog resume a normal, active lifestyle with less of a risk of developing severe arthritis in the joint with time and wear.

The second common surgery that involves changing the angles of the bones of the knee is called a Tibial Plateau Leveling Operation (TPLO). Again, this is a surgery that involves cutting bone and this time rotating it to provide more stability.

11 years old and lookin' good with two bum knees.

11 years old and lookin’ good with two bum knees.

Both of these surgeries are extremely effective, but unfortunately they also come with a fairly large pricetag. The good news is that they are generally successful as long as the post-operative instructions for restriction, range of motion exercises, and a very gradual return to normal activity are followed.

There is a very owner-effort-intensive period following surgery. The dog must be kept quiet, must be leash-walked to potty, and cannot be allowed to run or jump. For many dogs, this involves being kept in a crate. It’s hard to keep a dog mentally entertained enough to keep him sane while he’s not allowed to run or play, but it’s crucial if the surgery is going to be successful. When you get tempted to let your dog have “just a little bit of freedom”, just visualize the enormous vet bill you just paid to have his knee fixed and remember how much you don’t want to pay to have it fixed a second time.

Rehab is another option for post-op dogs. A variety of exercises are used to help increase the strength in the repaired leg in ways that are safe and gradual. A lot of times, an underwater treadmill is used, so that a dog is able to walk and use the leg without having to bear all of his weight on it.

So the good news is that for this common injury in dogs, there are a lot of options and surgery is generally successful. The downside is that surgery and rehab are very expensive, the recovery process is quite time-consuming and can be stressful, and the dog will end up with some measure of arthritis in the injured knee no matter what. But surgery does make a tremendous difference, especially for dogs who are high-energy and athletic, and many of them can return to the lively, fun life they were leading before they got hurt.

For more information, check out these websites:
ACVS page for Cranial Cruciate Ligament Disease
Information about rehab for dogs from West Chester Veterinary Rehab

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Posted by on May 15, 2014 in Dogs, Health


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