Original Research
Use of Acupuncture to Induce Cyclicity in Anestrous Mares

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Abstract

Acupuncture is part of an Eastern system of medicine used for diagnosing, treating, and preventing disease. It has been used for the treatment of reproductive disorders in both human beings and domestic species. We hypothesized that acupuncture could be used to induce cyclicity in anestrous mares. In experiment 1, six anestrous mares were treated with acupuncture at Bai Hui, governing vessel (GV)-2, bladder (BL)-22, BL-23, BL-31, and BL-33 twice a week for 3 weeks, then once a week for an additional 8 weeks, whereas six anestrous mares served as controls. In experiment 2, six anestrous mares received acupuncture stimulation at Bai Hui, GV-1, BL-22, BL-23, and BL-28, with electroacupuncture (10 minutes at 50 Hz) at BL-22 and BL-28 bilaterally. In addition, vitamin B12 (3 mL, 1,000 mcg/mL) was injected in the vaginal fornix at the 3, 6, and 9 o’clock positions around the cervix. Six anestrous mares served as controls. Examinations and treatments were carried out twice a week until ovulation. In both experiments, ovarian activity was examined in all mares by transrectal ultrasonography and blood sample was obtained twice a week to determine progesterone concentrations. The time to first ovulation for experiment 1 was 14.0 ± 0.7 and 13.5 ± 1.0 weeks (mean ± SD) for the control and acupuncture groups, respectively (P = .60). In experiment 2, the time to ovulation was 9.0 ± 0.6 and 10 ± 0.3 weeks (mean ± SD) for the control and acupuncture groups, respectively (P = .19). No significant difference was found between the treated and control mares in either study.

Introduction

The mare is a seasonal long-day breeder, with an 11-month gestation period. Mares naturally cycle during the late spring and summer, and would therefore normally foal in late spring or early summer. Nevertheless, many breed registries have assigned the annual birth date for horses in the Northern Hemisphere as January 1. Horse breeders therefore strive to have their mares foal as early in the year as possible, which likewise requires breeding early in the year. This creates difficulties because most mares are in anestrous during the winter. Hastening the onset of cyclicity by shortening anestrous is necessary to attain the goal of having mares foal earlier in the year.

Current methods for shortening the winter anestrous period and hastening cyclicity involve using either artificial light [1], [2], gonadotropin-releasing hormone analogs [3], [4], follicle-stimulating hormone [5], [6], follicular aspiration [7], or dopamine agonists such as domperidone or sulpiride [4], [8], [9]. Acupuncture has been used to treat reproductive disorders in human beings, horses, and production animals [10], [11], [12], and may offer an alternative method to shorten the winter anestrous period in mares.

A variety of point combinations have been used to influence reproductive function in other species [11], [13]. The most common points used are located in the conception vessel, the governing vessel (GV), and the bladder (BL) and kidney meridians, which lie alongside the dorsal spine and ventral midline [11], [13], [14]. Meridians are described as channels in which the energy flow of the body travels. Stimulation along points of the channels are said to move the energy flow toward or away from the target organ, as needed, thereby stimulating normal function. This change of energy flow is thought to stimulate the secretion of reproductive hormones [15].

Lin et al. [12] suggested that anestrous can be successfully treated with electroacupuncture at Bai Hui and GV-2 provided the animal is in otherwise good health. Although there have been no studies documented in physiologically anestrous mares, results from the use of acupuncture in other species have shown promising results. Fung treated 35 cows in anestrous due to ovarian pathology using a single-treatment at acupuncture site GV-2 and stimulated ovarian cyclicity in 91.5% of the cows [11]. Similarly, electroacupuncture treatment in rabbits has shown success in induction of ovulation [13].

Stimulation of acupuncture sites related to the reproductive tract in the cow and rabbit is proposed, but not proven, to activate the hypothalamic-pituitary axis. This could result in gonadotropin-releasing hormone secretion from the hypothalamus and the release of follicle-stimulating hormone and luteinizing hormone that stimulate ovarian activity [10]. If acupuncture will stimulate mares’ ovaries to produce follicles and start cycling during the anestrous period, then earlier breeding and subsequent foaling closer to January 1 can occur. The overall goal of this study was to induce earlier cyclicity and ovulation in anestrous mares using acupuncture treatments. The specific objectives were to document ovarian follicular activity, and ovulation in anestrous mares treated with dry needle acupuncture at the Bai Hui, GV-2, BL-22, BL-23, BL-31, and BL-33 acupuncture points in experiment 1 and with dry needle acupuncture at the Bai Hui, GV-1 and BL-23 points and electroacupuncture at the BL-22 and BL-28 points in experiment 2.

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Materials and Methods

This study was approved by the Institutional Animal Care and Use Committee at Louisiana State University.

Experiment 1

During the months of November and December 1999, all 12 mares in this study displayed a normal anestrous period as evidenced by absence of follicles >20 mm on the ovaries, and plasma progesterone concentration <3 nmol/L.

The time, in weeks, to ovulation was 14.0 ± 0.7 and 13.5 ± 1.0 (mean ± SD) after initiation of treatment for the control group and the acupuncture group, respectively (Fig. 5). Although two of the six treated mares ovulated before any of the control mares, there was no

Discussion and Conclusion

There are several acupuncture sites that have been noted to cause a stimulation of the ovaries in human beings as well as in animals. The acupuncture sites used in this study are only a few of the suggested points reviewed in the literature; however, no reported treatment involves stimulation of more than six paired points. The points chosen were, to the best of knowledge of the researchers, found to be the most efficient way to target the ovaries.

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Acknowledgments

Research was funded by the American Association of Equine Practitioners Therapeutic Options Research Grant.

The authors thank Dr. K Wolfsheimer, Endocrine Diagnostics and Consultation, Baton Rouge, LA, for assistance with the progesterone assays.

Current address: 4315 Marsh Bend, Deland, FL (A.S.N.-M.); Department of Veterinary Clinical Sciences, Veterinary Teaching Hospital, Columbus, OH (C.P.); Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA (L.C.); Veterinary Emergency Clinic and Referral Center, Toronto, Ontario, Canada (G.P.).

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