Using acupuncture to manage severe pain in horses and other animals is not a novel concept, but veterinarians have been hard at work lately combing research studies to better understand this complementary therapy’s usefulness, efficacy, and safety. During a presentation at the 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas, James Kenney, DVM, an equine practitioner from Clarksburg, N.J., presented an overview of acupuncture and equine pain.
"According to the World Health Organization, the effectiveness of acupuncture has been established in controlled clinical trials (in humans), and the use of acupuncture to control chronic pain is comparable with morphine without the risk of drug dependence and other adverse side effects," Kenney explained.
After an in-depth discussion of the physiologic mechanisms behind acupuncture and pain control, Kenney discussed clinical research on the use of acupuncture in animals.
"Currently, much of the practice of acupuncture in animals is based on the results of pilot research studies, case reports, and clinical experiences," he explained. "Compared with human acupuncture, the clinical application of veterinary acupuncture is in the early stages of development as a science."
Based on the findings of a 2006 systematic research review, he noted, there’s "no compelling evidence to recommend or reject acupuncture for any condition in domestic animals." Clinical trials are still yielding a mixed bag of results for acupuncture’s efficacy for treating a variety of ailments in horses:
Thoracolumbar Pain "Controlled clinical trials have shown significant improvement of thoracolumbar pain (i.e., back pain located between the withers and the pelvis) in horses using objective methods of pain evaluation," he explained. In one such study, he said, 15 horses in three research groups were treated with electroacupuncture (EA), phenylbutazone (Bute), or saline (controls). Using thoracolumbar pain scores, a blinded independent researcher concluded that the horses treated with EA had lower pain scores than horses treated with Bute and saline.
Another team of researchers conducted a randomized, double-blinded study on 23 sport horses with back pain. Kenney explained that the investigators identified each horse’s painful points using pressure algometry before employing EA at specific locations corresponding with those painful areas. "After five treatments, pressure-induced pain was significantly reduced at (painful points) in the treatment group compared with the control group," he noted.
Hoof Sole Pain Researchers have used controlled studies to evaluate acupuncture’s impact on lameness caused by sole pain, Kenney said. He discussed one study in which two independent evaluators assigned lameness scores to horses with artificially induced sole pain. The same evaluators examined the horses after they were treated with EA, a bupivacaine nerve block, or a saline nerve block. They found that EA reduced lameness scores significantly as compared to horses treated with the saline nerve block.
Visceral Pain While EA has been shown to help reduce visceral (internal organ) pain, regulate gastrointestinal motility, and improve regional blood flow, a study indicated that it was not quite as effective as butorphanol (a morphine-derived analgesic) for relieving pain elicited by rectal distension in one study.
In another study in which investigators assessed acupuncture’s potential for relieving pain caused by small intestine distension, Kenney noted that EA was ineffective in reducing the acute clinical signs. "These results indicate that acupuncture does not have a strong enough analgesic effect to block severe gastrointestinal pain."
Research in Other Species
Kenney briefly discussed clinical research in dogs supporting the use of acupuncture for certain situations:
- EA administered for canine postoperative following intervertebral disk disease surgery significantly decreased the amount of fentanyl (an opiate analgesic) required for pain during the first 12 hours as compared to controls. Researchers on the same study indicated pain scores were lower in the EA group 36 hours after surgery as well, but these values did not differ from controls at any other time period; and
- Researchers found that dogs treated for chronic hip pain resulting from hip dysplasia with gold bead implants had reduced pain and greater mobility than a control group at two weeks, three months, and six months following treatment.
"As is the case for humans, few adverse side effects have been associated with acupuncture in animals," Kenney explained. "In a review of 1,292 acupuncture treatments that were performed on 221 animals (cats, dogs, cattle, and horses), adverse reactions to acupuncture needles totaled four of 12,274 needles, or approximately one per 3,000 needles.
"Two of these reactions consisted of transient superficial edema (temporary fluid swelling) of the skin, and as they neither required treatment nor appeared to be painful nor were other more serious signs present, they were considered to be clinically trivial," he continued. "There was one abscess, which resolved with antibiotic treatment, and one seizure event in a 7-year-old spayed female Beagle that resolved without treatment and did not reoccur within a seven-month follow-up period."
Specifically in horses, 377 treatments performed on 74 horses yielded similar results. Kenney reported that a 10-year-old Hanoverian gelding being treated for–among other ailments–heel pain experienced mild swelling on the bulbs of his hoof at the treatment site. Kenney reported the swelling subsided after one week.
"There is a well-researched scientific basis for the mechanism of acupuncture analgesia, the extent and depth of which continue to expand," Kenney concluded. "Although there is research to support EA as an evidence-based practice for the management of back pain in horses, additional studies are needed in other clinical situations where analgesia may be required."