Downeast Dog News

Is There an Epidemic of ACL's?

By Judith K. Herman DVM, CVH | Oct 01, 2020

Q. My lab has been off and on lame in his right hind leg. At first, they thought he had Lyme, but the test was negative. Now they feel he injured his knee called an ACL. This doesn’t sound good.

A. Anterior cruciate ligament (ACL) or cranial cruciate ligament (CCL) are the same thing and is the name of one of the two ligaments that form a cross in the knee joint, known as the stifle in the dog. (I will use knee in this article.) These ligaments allow the knee to bend properly.

Injury can occur suddenly with blunt trauma. I saw a Husky who was run over by another Husky. She was very lame, and when I opened the knee to repair it, you could see the blood clot on the end of the torn ligament! Other dogs will strain their ligament over time. Eventually the strain weakens the ligament until it frays and tears. These dogs are off and on lame; eventually they become lame all the time. It is very common, when one ligament tears, the ligament in the other knee will tear.

Why do so many dogs have ligament issues in their knees and others don’t? We don’t know all the reasons for torn ligaments in the dog, but with more information on why, the better we can avoid such damage.

Let’s start with the first known fact. Overweight dogs at any age have more joint issues. A study done at Cornell University showed a litter of Labrador pups free fed puppy food verses a litter free fed adult food who had more joint problems than the adult feed group. The puppy food group were overweight and had more stress on their growing bones and joints. At any life stage, a dog who is overweight will suffer more joint problems than a dog of normal weight.

It is also known that early spay/neuter will slow down the closing of growth plates in the long bones of a dog. The slowing down of the closure will cause the pup to develop abnormally long legs and change the angles of his joints. The legs become straighter. If you think of the angles of the joints, like the hip to the knee to the hock, as shock absorbers, you will understand that a dog with normal angulation, joint angles, will have less wear and tear than a dog with straighter angles. The straighter the angle the more pressure there is on the joint. This pressure will eventually cause the joint to degenerate.

Sometimes a breed of dog has straighter legs than another breed. This is genetics. For the most part if Fluffy is going to be a house pet and goes on walks around the neighborhood, straight legs aren’t a problem. If your dog bounds through the woods or is an athlete, poor conformation will affect his ability to perform.

The last point to mention for causes is being in good condition. Fluffy can be a lap dog, or Bozo can be an agility and dock diving dog; just like us to stay healthy and injury free, they need to be fit. It doesn’t take much to work those muscles each day. If they exert themselves only on the weekends, there will be more injuries.

The objective of treatment for this injury is slowing down damage to the joint. It can be surgery. Depending on the weight and size of the dog, the type of surgery will vary. It may be a non-surgical intervention such as physical therapy, laser, nutraceuticals, acupuncture, prolotherapy, and homeopathy.

The bottom line is injuries happen but being proactive can avoid a lot of heart ache and money. Keep your best friend’s weight down, stay active throughout the week instead of just on weekends. Lastly, pick activities for you and your dog to enjoy and that they are built to do.


Judith K. Herman DVM, CVH

Animal Wellness Center

Augusta, Maine