Infraspinatus Contracture

Injury of the infraspinatus muscle is uncommon and is seen most often in highly active dogs, typically after intense exercise such as bird hunting. It may be more likely when a dog is not adequately conditioned beforehand. Prevention focuses on maintaining good overall fitness and increasing activity gradually, similar to recommendations for human athletes.

After a muscle injury occurs, the goal is to limit ongoing damage by controlling inflammation and using appropriate rehabilitation (physical therapy and supportive modalities such as laser therapy). In some cases, the injury heals with enough scar tissue to restrict shoulder extension, producing an infraspinatus contracture. This later-stage condition is generally not painful, but it can cause functional limitation. Surgical correction of this contracture is usually simple and highly successful. Most dogs return to full activity after surgery, and long-term problems are uncommon.

During running, a dog fully extends the shoulder and then uses the infraspinatus and other muscles to help flex and pull the limb back to propel the body forward. With prolonged or very vigorous running, the infraspinatus is susceptible to overuse, and fibers may tear, stretch, or otherwise become damaged. This is often observed early in bird-hunting season and is consistent with the “weekend warrior” pattern—enthusiastic but poorly conditioned dogs doing too much too soon.

A comparable scenario in human athletes is a hamstring strain, where muscle fibers tear during activity. Once the fibers are damaged, inflammation develops. This inflammatory phase is painful and is associated with warmth, swelling, and tenderness. Stretching the muscle—most notably during shoulder extension—is also painful. Dogs therefore tend to carry the limb in a way that avoids shoulder extension. Some will hold the leg up and move on three legs; others will take a much shorter stride, creating a clear limp.

A key feature of muscle healing is that it occurs largely through fibrosis (scar tissue) rather than true regeneration of severely damaged muscle cells. Over approximately 1–2 months, the acute inflammation resolves and pain diminishes, so the dog may appear more comfortable and use the limb more. However, as healing continues, scar tissue increases. Normal muscle is elastic, while scar tissue is not. As the scar matures, it becomes firmer and contracts, leading to a persistent lameness that often looks non-painful. Some dogs may even hold the foot off the ground while sitting.

At this stage, the disability results from a stiffened, scarred infraspinatus that prevents normal shoulder extension. The shoulder remains flexed but is well-healed and typically pain-free. Because the limb cannot reach forward normally, it effectively functions as a slightly shorter leg, impairing normal walking and running.

Diagnosis of infraspinatus contracture is commonly made through physical and orthopedic examination. Radiographs may be recommended to ensure there are no concurrent bone or joint abnormalities. If needed, advanced imaging such as musculoskeletal ultrasound or MRI can be used to evaluate the muscle and its tendon insertion more specifically.

A practical advantage of this condition is that the infraspinatus is only one of several muscles contributing to shoulder stability and flexion; dogs can generally function well without it. Surgical treatment takes advantage of this by releasing the contracted structure.

The procedure involves cutting the infraspinatus tendon near its attachment to the humerus and releasing nearby tissues as needed to restore full shoulder range of motion. The release can be immediate and sometimes produces an audible or palpable “pop” as the restriction resolves. After the small surgical incision heals, dogs typically appear comfortable and functional, without the need for strict long-term limitations.

Because the surgery is relatively minor and causes limited tissue disruption, postoperative pain is usually moderate for a few days and is typically well controlled with standard pain management. By about two weeks, dogs are commonly comfortable at the incision site.

A potential minor complication is an incisional seroma, a fluid pocket under the skin near the surgical site, which may form due to fluid leakage or tissue motion. Most seromas resolve on their own, sometimes aided by warm compresses. If a seroma becomes large and does not reabsorb, it may need needle drainage. Careful technique and strict rest for about four weeks can reduce the likelihood of seroma formation.

Once healing is complete, most dogs can return to normal activity without restrictions. Gradual reconditioning is advised before future intense exercise to help prevent similar issues in the opposite shoulder.