The Science Behind Acupuncture

The Science Behind Acupuncture

Photo: Anne M. Eberhardt/The Horse

Exploring the evidence regarding the use of acupuncture in equine medicine

Following President Nixon's visit to China in the 1970s, reports of acupuncture use began to crop up in the U.S. media. Fascination with acupuncture and other forms of complementary and alternative medicine (CAM) such as Chinese herbal medicine took hold, and today these forms of medicine are being used more frequently.

However, according to Peggy Fleming, DVM, AP, owner and operator of Florida Acupuncture Center, in Dade City, "controversy still exists over the efficacy of these therapies, including acupuncture."

The most widely recommended use of equine acupuncture has been to help manage chronic pain. Dietrich Graf von Schweinitz, BSc, DVM, MRCVS, Cert Vet Acu (IVAS), president of the Association of British Veterinary Acupuncturists and a veterinary surgeon at Southern Hills Equine Veterinary Clinic Ltd., in Putternham, Guildford, U.K., believes acupuncture is an effective treatment for chronic pain, among other conditions.

As presented by Graf von Schweinitz at the 49th British Equine Veterinary Association Congress, held in 2010 in Birmingham, England, other indications for acupuncture have been proposed (although scientific evidence to back them up is lacking), including:

  • Diagnosing and treating musculoskeletal and neuromuscular disorders;
  • Identifying causes of poor performance and training resistance; and
  • Addressing eye problems; skin diseases; endocrine (hormonal) disorders; circulatory and lymphatic faults; respiratory conditions (heaves or chronic obstructive pulmonary disease); digestive disorders (colic); and reproductive problems.

In this article we will look at what acupuncture is, explore some theories and hypotheses that could explain how acupuncture might work, and describe studies that have been conducted to evaluate acupuncture's efficacy in some of the above-described scenarios.

What is Acupuncture?

Ed Boldt Jr., DVM, owner of Performance Horse Complementary Medicine Services, in Fort Collins, Colo., describes acupuncture as "the insertion of a needle through the skin at specific acupuncture points to treat or prevent disease, including pain." One controversy lies in the fact that after decades of work researchers have not yet demonstrated that such "specific" acupuncture points exist.

"In addition to using solid, usually stainless steel needles, acupuncture therapy includes using other means of stimulating acupuncture points such as aquapuncture, hemoacupuncture, and cold laser/infrared (IR) stimulation," Boldt explains.

The traditional technique of using only the needle is referred to as "dry needling." Aquapuncture involves injecting a small amount of fluid (e.g., vitamin B12) into the acupuncture point--acupuncturists explain this is done so the liquid will continue to stimulate that point after the needle is removed. Hemoacupuncture involves "bleeding" an acupuncture point with a hypodermic needle. Cold laser and IR units can be applied to "hard-to-reach" acupuncture points, such as the head (eyes) and legs, which would otherwise be difficult or unsafe to treat using other acupuncture techniques. Electroacupuncture involves the electric stimulation of acupuncture needles once they have been inserted through the horse's skin at the selected acupuncture points.

How Does it Work?

Various theories and hypotheses exist to explain how exactly acupuncture could benefit animals. Many of these suggest acupuncture's effects are at least partly attributable to the release of endorphins and monoamines, which are special chemical messengers (neurotransmitters) involved in natural analgesia (i.e., pain relief).

Fleming explains that by strategically inserting needles along individual meridians at specific acupuncture points, a veterinary acupuncturist can conceivably balance the flow of energy through a horse's body.

"Acupuncture needling causes microtrauma that can induce a small, controlled inflammatory effect," adds Boldt, who believes the inflammation improves local tissue blood flow.

But do we know that these acupuncture points and meridians really exist? According to David Ramey, DVM, a private equine practitioner in Southern California, the consensus of scientific information says, overwhelmingly, no.

"A review of the existing historical and experimental evidence provides no convincing evidence that either acupuncture points or meridians exist as discrete entities," Ramey wrote in his article, "A Review of the Evidence for the Existence of Acupuncture Points and Meridians," which he presented during the AAEP's 46th Annual Convention, held in 2000. "No evidence for the existence of such things has been provided since," Ramey adds.

Why Use Acupuncture?

Despite opposing viewpoints, some veterinarians are applying acupunture in their daily practice. According to Graf von Schweinitz, acupuncture facilitates and stimulates the body's natural healing capabilities and helps return the nervous system to its "normal" level of activity to decrease pain and/or restore basic body functions. "This includes reducing anxiety, increasing the levels of endogenous (naturally occurring) opioids, and normalizing the autonomics (involuntary nervous system that regulates all visceral activity)," he explains. Thus, he says one reason owners and veterinarians might turn to acupuncture is to reduce their use of pharmaceutical drugs.

For instance, Graf von Schweinitz believes "horses treated with acupuncture for certain conditions such as chronic pain due to musculoskeletal disorders can result in the reduction of non-steroidal anti-inflammatory drugs like phenylbutazone (Bute) or steroids."

Using these drugs less, especially in older horses, can help minimize the (relatively uncommon) occurrence of drug-related side effects such as liver and kidney damage. However, research results have not shown that acupuncture actually reduces the need for such medications in horses.

Yes, But Does it Work?

With the widespread adoption of evidence-based medicine, researchers have conducted and published a number of scientific studies attempting to answer the question of whether acupuncture works for horses with particular conditions. Below we briefly describe a few of the most up-to-date studies assessing acupuncture's efficacy in diagnosing, preventing, or managing musculoskeletal, respiratory, and reproductive tract disorders.

Musculoskeletal Disorders Let's look at how acupuncture can help practitioners actually diagnose lameness in horses, rather than just treat chronic pain. Brad Luckenbill, DVM, from The Pony Express Veterinary Hospital Inc., in Xenia, Ohio, is an acupuncture proponent and has presented his views of integrating acupuncture into a standard lameness examination at various veterinary conferences including the North American Veterinary Conference. According to Luckenbill, veterinarians can use acupuncture in concert with visual assessment, flexion tests, diagnostic joint blocks, and imaging techniques (X ray or ultrasound). The acupuncture phase of a lameness examination includes checking the horse over for sore acupuncture points.

Luckenbill notes that the front foot and fetlock; the knee; the shoulder, neck, and back; and the hips, stifles, and hocks all lend themselves to evaluation via an acupuncture examination. In contrast, he explains that the hind feet, fetlocks, pastern joints, and tendons cannot be evaluated using acupuncture.

Respiratory Tract Disorders Respiratory tract disorders are the second-most-common cause of poor performance in athletic horses and are an important quality-of-life concern even in nonathletic or older horses--for example, those with inflammatory airway disease (IAD). In athletic horses "roaring," also known as laryngeal hemiplegia, is a relatively common cause of poor performance. Paralysis of the left recurrent laryngeal nerve causes the left arytenoid cartilage (part of the larynx or voicebox) to "droop" into the airway, obstructing air passage. Attempts to manage this condition via medical or surgical approaches might either be unsuccessful or impractical (e.g., if the condition develops during the sale season, precluding surgical treatment). Thus, acupuncture has been proposed as an alternative treatment option.

One research team from the University of Florida and the College of Veterinary Medicine at Chonbuk National University, in South Korea, performed electroacupuncture in 18 Thoroughbred racehorses diagnosed with mild to moderate laryngeal hemiplegia. Horses were treated once per week for a total of three to seven sessions per horse, depending on how severe (which grade) the hemiplegia was (i.e., the more severe, the more sessions). The grade of laryngeal disease improved in all horses, and most horses tolerated the procedure well without requiring sedation. However, there was no objective measure (of airway function post-treatment), and the study authors suggest that a controlled study is needed.

An Austrian research team also assessed veterinarians' ability to detect equine herpesvirus-1 (EHV-1) infection with acupuncture in horses exhibiting decreased performance. All 40 horses included in the study underwent physical and neurologic examinations. The researchers then tested case and control horses' acupuncture points on the bladder meridian for sensitivity reactions. The study results revealed a significant difference in skin sensitivity in the cervical (neck), sacral (pelvic), gluteal, and flank regions between case and control horses. Specifically, all case horses were sensitive when researchers manipulated all the acupuncture points thought to be associated with EHV infections. In contrast, few control horses were sensitive to manipulation of these same acupuncture spots. However, the study authors were unable to actually detect the presence of the virus in any of the study horses' blood samples, or any difference in antibody levels against EHV between the case and control horses. Thus, they did not detect an "unequivocal" association of acupuncture point sensitivity with EHV infection.

Researchers also have been looking at using acupuncture to treat heaves (IAD, formerly known as chronic obstructive pulmonary disease). In a study authored by Michigan State researchers and published in 2004, "A single acupuncture treatment during an attack of heaves causes no more improvement in lung function than does handling the horse." These results prompted the study authors to conclude, "Acupuncture should not replace conventional medical treatments for heaves."

Reproductive Issues Some researchers and reproductive equine veterinarians are using acupuncture for many reproductive conditions. Wendy Schofield, DVM, previously of Hagyard Equine Medical Institute and currently in Key West, Fla., looked at the body of available research and reviewed the use of acupuncture in equine reproduction in 2008.

"Despite the limited body of clinical data on the use of acupuncture in horses, there are already some convincing studies in other species that demonstrated that acupuncture can impact the hypothalamic-pituitary-gonadal axis," says Schofield. This axis refers to a link between the hypothalamic region of the brain, the pituitary gland, and the gonads, which all produce hormones (e.g., follicle-stimulating hormone, estrogen, and testosterone) that impact and control reproduction.

According to a 2008 review article on the use of acupuncture in reproduction medicine (published in Theriogenology), some veterinarians view acupuncture as a successful technique for treating uterine fluid and urine pooling in mares, especially when used in conjunction with conventional treatment methods such as oxytocin uterine lavage and antibiotic infusions. The review article also states mares in anestrus (not cycling), transition (the period between the anestrus, nonbreeding season and the breeding season), or those with irregular cycles might benefit from acupuncture.

"Although there is insufficient evidence to support the theory that acupuncture can potentially cause abortion in mares, acupuncture should still be pursued carefully in pregnant mares, and electroacupuncture should be avoided," Schofield cautions.

Acupuncture in stallions has primarily been used for pain management (e.g., chronic back pain or other musculoskeletal issues), but veterinarians have also made efforts to treat cryptorchids (male horses with one or both testicles retained in the abdomen) and manage behavior issues such as poor libido or excessive aggression with apparently encouraging results; however, acupuncture has not been as well-studied in stallions as in mares.

"The physiology of acupuncture and its efficacy remain to be defined," Schofield adds, noting she believes veterinarians should continue to study acupuncture in equine reproduction.

Take-Home Message

In 2006 a systematic review was published in the Journal of Veterinary Internal Medicine reporting on the effectiveness of acupuncture in veterinary medicine. The authors of that report wrote, "On the basis of the findings of this systematic review, there is no compelling evidence to recommend or reject acupuncture for any condition in domestic animals." The authors did, however, concede that "some encouraging data do exist that warrant further investigation in independent rigorous trials."

In light of increased interest in and use of CAM in the equine industry, data generated via well-designed, controlled clinical trials will certainly be welcome to help support or refute using acupuncture in horses. Even so, "calls for good data have now been made for a few decades, but a strong body of evidence is still lacking," says Ramey.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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