The Modern Equine Vet
December 2021
Vol 11 Issue 12 2021
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Chiropractic Care

Can Chiropractic Care Reduced Pain and Stiffness in Limb Lameness?

 By Marie Rosenthal, MS

Although a new study found no significant changes in lameness scores after chiropractic care, there were significant changes in the severity of pain. Some locations also saw less muscle stiffness and hypertonicity.

“Therefore, we concluded that chiropractic care may be beneficial for addressing compensatory pain that results from a primary lameness,” explained Samantha Parkinson, DVM, a veterinary resident at Colorado State University, College of Veterinary Medicine, who presented the data at the American Association of Equine Practitioners Annual Convention & Trade Show, which ran from Dec. 4–8, in Nashville, Tenn.

Interest in chiropractic care for horses has been increasing. One of its advantages is that it “is affordable to the majority of our veterinary clients,” she said, but should it be recommended for lameness involving the limbs?

Dr. Parkinson and her colleagues did a study to evaluate the effects of chiropractic care on limb lameness and concurrent axial skeleton pain and dysfunction.

The interactions between the axial and appendicular skeleton are important to consider when trying to intervene in a horse with lameness. “When one leg is lame, there’s altered weight-bearing to increase the weight on the other 3 limbs as the horse attempts to unload the painful leg,” she said, which results in changes throughout the axial and appendicular regions.

Previous studies found that horses with primary limb lameness have back pain in 23% to 32% of cases; and horses with primary back pain have a concurrent limb lameness in 68% to 85% of cases. “This highlights the importance and the significance of these interactions and our need to be able to address them,” she said.

“While we have evidence supporting the use of chiropractic for axial skeleton pain, we haven’t to date looked at its effect on lameness,” she said.

The goal of their study was to evaluate the efficacy of chiropractic care in reducing limb lameness and concurrent axial skeleton pain and disfunction. “We hypothesized that chiropractic treatment would improve measures of lameness, as well as our axial skeleton pain and dysfunction,” she said.

Twenty polo horses with grade 1-to-3 lameness on the AAEP lameness scale were enrolled in the blinded randomized controlled clinical trial. Ten horses were in each group. Some horses had multilimb lameness. Horses with grade 4 or 5 lameness were excluded from the study because the researchers felt they needed more work-up.

They were evaluated at day 0, day 14 and day 28 by a single, blinded examiner.

A different blinded examiner, trained in chiropractic care and boarded in sports medicine rehabilitation, provided chiropractic treatment for 10 horses on day 0, 7, 14 and 21. Both the axial and appendicular skeletons were evaluated and restrictions—the chiropractic term for pain, stiffness and restricted motion—were addressed individually.

The control horses were asked to stand for an equivocal amount of time.

They used both subjective and objective methods for assessing the success of the treatments. For the subjective lameness exam, a single examiner watched the horse trot in a straight line on asphalt and scored each limb 1 through 5. The scores were added for a cumulative score.

The objective lameness score used the Equinosis lameness locator with 2 inertial sensors, which evaluate asymmetry, and 3 measurements were taken with a gyroscope along the spine.

They then checked spinal reflexes, and the horses’ range of motion and stretching.

The spinal examination palpated the neck in the thoracolumbar and gluteal regions for pain, stiffness and muscle ethnicity.

“Finally, we evaluated spinal flexibility using 5 different baited carrot stretches to assess the flexibility throughout the cervical spine, as well as the thoracolumbar regions,” she explained. “Using carrots, we asked the horse to flex by holding the treat at the level of the withers for an upper cervical stretch. Next, we moved the treat to the level of the girth, asking the horse to bend the middle cervical region. And finally, we moved the treat to the level carpus asking for a caudal cervical flex.

“The last 2 stretches involved, both combined cervical and thoracolumbar stretches,” she said.

There was no change in measures of lameness, nor in mechanical nociceptive thresholds between the treated and untreated horses, she said.

However, “there were significant changes noted in the severity of the pain in our treatment group,” she said, both in spinal pain severity and affected cervical vertebral levels.

They also saw a decrease in muscle hypertonicity and spinal stiffness in a number of locations in favor of the treated group.

Dr. Parkinson said the study had several limitations. They did not localize the origin of the lameness, and the lameness was not addressed nor treated because they wanted to evaluate the effects of chiropractic care alone.

In addition, the animals were second-career polo ponies, with bilateral multilimb lameness. Since the lameness locator is looking for asymmetries, they might be less prominent in a horse with bilateral lameness.

“Additionally, the majority of them had chronic lameness. When we have chronic lameness, we increase our risk of central sensitization or the development of neuropathic pain, which may not be amenable to chiropractic care,” Dr. Parkinson said.

More study is needed “to determine where chiropractic may be the most beneficial and where it will have the largest effect,” she said. MeV

Chiropractic Care

Chiropractic care is a form of manual therapy that affects the musculoskeletal and nervous systems by using a high velocity low amplitude (HVLA) thrust during motion palpation of the horse.

Individual joints and articulations are evaluated for pain, stiffness and range of motion. When alterations in these parameters are identified—also referred to as a restriction—a specific articulation is moved into the paraphysiologic space.

An HVLA thrust stimulates stretch receptors within the muscle to induce the muscle to relax.