Sweeney Shoulder Explained

Sunday, February 26, 2012
Posted by America’s Horse

For Rebekah Ellis, it was a horse owner’s worst nightmare when she found her horse shaking uncontrollably in the corner of the pasture in May 2009, unable to walk after apparently being kicked by another horse. “It was awful,” Rebekah says about finding her beloved horse, Fancy Bonanza Doll. “I tried to move her, but she would not budge. I called the vet out, and there was no visible injury that we could see. He finally got her to walk by smacking his hat to her butt. Her walk was horrific.”
Rebekah had three vets from the Kenosha, Wisconsin, area examine “Fancy,” with little success at a diagnosis. She then took the mare to a specialist, who determined that it was an injury to the suprascapular nerve, a condition commonly called “Sweeney shoulder.”

The suprascapular nerve controls the shoulder muscles that bring the front leg forward. Without proper nerve function, the muscles along the shoulder blade cannot function correctly. The muscles degenerate, and the horse is unable to move her leg properly.

Dr. Ed Boldt of Performance Horse Complementary Medicine Services in Fort Collins, Colorado, explains that the condition was first seen more than a century ago as the result of poor-fitting harness on working draft horses. The collar placed too much pressure on the nerve and caused damage.

With working draft horses much less common, now the Sweeney shoulder condition is usually caused by a traumatic injury, according to Dr. Justin Harper of Texas Specialty Veterinary Services in Boerne, Texas. He says most cases are seen after a natural disaster like a hurricane or tornado when horses spook and run into a tree or other object and cause traumatic damage to the shoulder. A blow to the area can also cause it, like with Rebekah’s horse being kicked.

Since the condition is now much more rare, many vets are unfamiliar with the injury. Dr. Boldt says in his 26 years of veterinary practice, he has seen fewer than 10 horses with Sweeney shoulder injuries.

At first, the symptoms may be hard to pinpoint.

“If the nerve is damaged, the horse will not want to put his leg forward,” Dr. Boldt says. “Sometimes that will be subtle, but then over time, the muscle starts withering and shrinking because it doesn’t have that nerve supply. In an advanced case, the muscle in the front part of the shoulder, right on the shoulder blade, is going to be atrophied.”

As with most injuries, the quicker the horse owner or veterinarian identifies the problem and begins treatment, the more likely the horse is to make a full recovery. However with a damaged nerve, the prognosis is uncertain.

If you suspect your horse has this condition, Dr. Harper recommends a full examination with radiographs to rule out fractures of the forelimb. After diagnosis of Sweeney shoulder, the horse should receive a regimen of nonsteroidal anti-inflammatory agents and pain medication. The horse should also be on a controlled-exercise regimen and physical therapy.

Dr. Boldt has treated horses with suprascapular nerve damage using electrostimulation therapy with some success.  “It is basically electroacupuncture, running electricity through the affected area similar to a transcutaneous electrical nerve stimulation (TENS) unit in people.”  This approach helps give the nerve time to heal while controlling the horse’s pain and keeping the horse active so the muscle doesn’t atrophy.

Dr. Harper explains: “With any injury of the musculoskeletal system in the horse or any other animal, pain causes the problem to become worse over time, so if you can break that pain cycle, then the animal is going to use that leg or limb and therefore eliminate some of the secondary complications that happen from nerve injury or muscle injury, such as contraction and disuse atrophy.”

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Photo: Eight months after surgery, Fancy enjoyed romping in the pasture. The muscles affected by the injury were still noticeably smaller than normal, but she continued to improve. Photo courtesy Rebekah Ellis.