You play tennis long enough, you will likely tear your rotator cuff,” says Tufts veterinary orthopedist Michael Kowaleski, DVM. “A dog does dog things long enough — landing on his front legs jumping down the stairs, and so on — and the shoulder cuff can eventually get torn that way, too.”
In fact, shoulder lameness resulting from wear and tear in middle-aged and older large-breed dogs is fairly common. As in people, the cuff of muscles that supports the shoulder joint can tear, stretch, or otherwise become compromised after years of use. You’ll often see an affected dog limping in pain on a front leg. But whereas a person can wear a sling for weeks to months to repair the injured muscle and follow instructions not to use the affected arm while it heals, a dog cannot. “Try telling a dog not to jump off the back deck, which he might have been doing every single day for most of his life,” Dr. Kowaleski says. “He doesn’t get the concept of ‘restricted activity.’”
Fortunately, he doesn’t have to.
Enter extracorporeal shockwave therapy
Sometimes, a joint problem bad enough to require surgery is caused by a tear in one of the ligaments that stabilizes the joint. The tear makes the joint too loose, which leads to lameness — and pain. But a surgery can stabilize the joint by cutting the bone in the area in such a way as to change the force in the joint so the ligament is no longer needed. The dog is back on his feet the next day, with complete healing occurring within just a few months.
But the shoulder joint is unique, with only muscle composing the cuff that holds it in place. There’s no ligament for a surgeon to manipulate. Thus, when the cuff tears, “it’s a different mechanism of ‘too loose,’” Dr. Kowaleski says. “You have to repair the muscle itself, which is what makes surgery so difficult to recover from.”
Fortunately, by aiming shockwaves at a dog’s shoulder with a technique known as extracorporeal shockwave therapy, a veterinarian can heal the muscle. “At Tufts, it’s our first line of treatment for a dog with a shoulder problem,” Dr. Kowaleski says. “By the time a dog gets to us, he usually has been limping for months, putting as little weight as possible on the affected leg. He has already been rested and given pain relievers, and they haven’t worked. The shockwave therapy combined with rest usually does the trick.”
How shockwave therapy works
Extracorporeal (outside the body) shockwave therapy looks a lot like ultrasound. The doctor runs a probe with a squishy tip along the dog’s shoulder, aiming the waves at the damaged muscle tissue. They penetrate the dog’s body by two inches, vibrating the injured muscle as they do so. The vibrations accomplish a number of things:
Release of growth factors. These growth factors released by cells in the area stimulate growth of fibrous tissue, which helps tighten the muscle via scarring. That provides more stability for the joint.
Breaks up mineral deposits. Calcium deposits can develop in the injured muscle tissue, and that hardness occurring where it’s not supposed to can increase pain. But the shock breaks the mineral deposits into multiple pieces. It’s similar to breaking up bladder or kidney stones with shockwaves. “Different machine, same technology,” Dr. Kowaleski says.
Creation of new blood vessels. The shockwaves cause the release of cytokines, proteins released from certain cells that are necessary for blood vessels to form. The process is called neovascularization, and the extra blood vessels help carry oxygen and other nourishment to damaged muscle to help it heal better.
Increased collagen formation. The shockwaves encourage collagen to form in the affected area, which helps rebuild compromised muscle.
Shockwave therapy even has a painrelieving effect, which is why some veterinarians also use it on elbow, hip, or knee arthritis in dogs. But it can actually heal a rotator cuff.
If your dog is diagnosed with a rotator cuff injury that is causing him limited mobility and great pain, it’s worth having a discussion with your pet’s doctor about whether extracorporeal shockwave therapy might be the way to go.
