I am Your Dog’s Gracilis Muscle

 

You might have never heard about a dog’s gracilis muscle, but this muscle is one that certain dog owners may never forget about once their dog develops problems with it. Just as in humans, a dog’s body is made of several muscles which allow force and motion. It is thanks to your dog’s muscles after all that your dog can maintain and change posture, move about, and ultimately live his life, considering that even the heart is muscle. The gracilis is an important muscle of your dog’s hind leg that can be in certain circumstances prone to injury. So today, let’s discover more about your dog’s gracilis muscle, the role it plays and potential problems this body part may be prone to.

Introducing Your Dog’s Gracilis Muscle

Hello, it’s your dog’s gracilis muscle talking! My name derives from the ancient Latin word “gracilis ” meaning slender, thin. And if you take a look at me by taking a peek at  the picture on the left, you may have a clear idea why I am called this way.

I am found in your dog’s hind limb, and more specifically, the inner surface of the thigh. I am categorized as a skeletal muscle meaning that I am a “voluntary muscle” anchored to bone and used to allow locomotion. 

I Create Motion

Yes, as mentioned, as many of your dog’s other muscles, I am responsible for allowing motion. What do I do exactly? I allow adduction of the thigh, that is, movement of  the limb towards the body, extension of the hip and extension of the hock. Quite a lot, for a thin muscle like me, huh?

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When Things Go Wrong

The most common type of injury affecting me, is a muscle contracture, also known as fibrotic myopathy. What exactly is a muscle contracture? The term may sound familiar but it’s different from a muscle contraction.

While a muscle contraction is the normal process of a muscle temporarily shortening when it’s being worked, a contracture is a pathological, abnormal shortening of muscle tissue, causing it to become resistant to stretching which can lead to long-term disability.

You see, when I am subjected to injury, scar tissue, under the form of fibrous connective tissue may form. However, sometimes, I may be almost entirely or completely replaced with fibrous connective tissue. Now scar tissue is less flexible than muscle fibers and therefore it leads to shortening which may limit my ability to allow a dog to to flex or extend the leg. Dogs affected by a gracilis contracture may therefore show signs of pain in the acute phases, lameness, a decreased range of motion and a characteristic gait.

The signature gait is characterized by the affected leg being raised with a jerky motion, with the hock flexed and rotated laterally, and a shortened stride due to the dog being unable to fully extend the ankle, knee, and hip joints. A video though is worth 1,000 words, so to give an idea of what happens to me when I am injured, you are better off watching it to see the gait.

In the greyhound racing business,  injury caused by me is often referred to as “dropped muscle” because affected dogs may develop a bulging area in the inner area of the dog’s thigh. Generally, this type of injury is most commonly seen in German Shepherds and Shepherd related breeds, but it can be present in many other large breed dogs with an active, working lifestyle.

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 “Although fibrous scar tissue provides tensile strength and plays a part in normal muscle healing, excessive scar tissue impedes muscle fiber regeneration and interferes with muscle contraction and relaxation, resulting in varying degrees of mechanical lameness.”~ Sherman O. Canapp

Did you know? Mechanical lameness refers to lameness that is not caused by pain but rather is triggered by a physical abnormality, such as presence of scar tissue, that prevents the normal motion of the leg.

As seen, I am an important structure that requires attention. If your dog is engaged in sporting events, it may help me, along with my other fellow muscles, if you could ensure proper conditioning and allow appropriate warm-ups and cool-downs. Passive stretching and massage before events is also helpful! Consult with your vet or a vet specializing in canine sports for the best ways to take care of me and prevent problems. I hope this has helped you understand me better,

Best regards,

Your Dog’s Gracilis Muscle

Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog has problems with his hind leg, please see your vet for diagnosis and treatment.

 

References:

• DVM360, Hind limb sprains and strains (Proceedings) retrieved from the web on December 26, 2016.
• Vaughan LC. Gracilis muscle injury in greyhounds. J Small Anim Pract 1969;10(6):363-375.
• Lewis DD, Shelton GD, Pias A, et al. Gracilis or semitendinosus myopathy in 18 dogs. J Am Anim Hosp Assoc 1997; 33:177-188.
• Vet Surgery Central, Semitendinosus and Gracilis Fibrotic Myopathy, retrieved from the web on December 26, 2016
• Preventing Injuries Focus on Canine Sports Medicine By Debra Canapp, DVM, CCRT, CVA and Chris Zink, DVM, Ph, retrieved from the web on December 26, 2016.

Photo Credits:

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