The Use of Acupuncture in Small Animal Reproduction
Joni L. Freshman, DVM, MS, DACVIM
AcuPets
3060 Woodview Court
Colorado Springs, CO 80918
Canine Consultations
3060 Woodview Court
Colorado Springs, CO 80918
Corresponding Author
Joni L. Freshman, DVM, MS, DACVIM
3060 Woodview Court
Colorado Springs, CO 80918
Phone: (719) 210-3918
FAX: (719) 457-5913
e-mail: tervet@zephyre.net
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1. Introduction
Acupuncture is an ancient technique; fish and bone needles may have first been used in
China approximately 3000 years ago (1, 2). In 650 BCE Bai-le Zhen Jing, considered an
expert in equine acupuncture, wrote the Canon of Veterinary Medicine (3). In the late
Zhou dynasty (400-200 BCE) the Yellow Emperor’s Classic of Internal Medicine (Huang
Ti Nei Ching) was written (3). This is considered a key acupuncture text.
Chinese medicine, including acupuncture, was based on thousands of years of
observation of patterns of illness and wellness. These concepts are quite different from
conventional Western paradigms of disease and body function. We now have
neurophysiologic bases for many of the observations of how acupuncture affects the
body. Acupuncture’s effectiveness is correlated with its effects on the neurophysiology
and hormonal mechanisms of the body.
In-depth knowledge of Chinese medicine paradigms is not necessary for the successful
use of acupuncture; however it may lead to a deeper or different understanding of
complex disease. This author does not consider biomedical acupuncture and TCM
acupuncture to be mutually exclusive. We should not ignore the new scientific
information that delineates the mechanism of action of acupuncture. We should also not
ignore thousands of years of observational information simply because we can now detail
the neurophysiologic basis of acupuncture’s effects.
Acupuncture typically refers to the use of needles alone (dry needles). Also included in
the modality are aquapuncture, the injection of liquid—often B12—into acupoints, and
electroacupuncture stimulation (EAS). Moxibustion is the addition of a burning herb over
acupoints or in association with the needles placed in acupoints.
2. Physiology of acupuncture
The location of acupoints in small animals has been transposed from information in
humans and other animals (horse, cow), as the use of acupuncture in companion animals
is relatively recent. Current research is ongoing to histologically define acupoint
locations in the dog.
Acupuncture points typically correspond with points where small nerve bundles penetrate
the fascia, are close to nerves, or close to blood vessels which have their own innervation
or motor points in muscle (4, 5). The TCM meridians or channels often follow the
propagated sensation along a nerve, and some may follow lymphatic channels (4, 5).
A brief review of specific neuroanatomy and physiology is necessary to understand the
biomedical mechanism of acupuncture action. There are specific nerve fiber types within
peripheral nerves. The fastest conducting is A-alpha, a large diameter fiber from Golgi
tendon organs and muscle spindle endings (5, 6). A-beta and A-gamma originate from
cutaneous tactile receptors and flower-spray endings of muscle spindles (5, 6). A-delta
fibers are small diameter, thinly myelinated, and carry temperature, pricking and sharp
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pain, and crude touch (5,6). C fibers, being unmyelinated, are the slowest conducting, and
carry itch, temperature, crude touch, and aching and burning pain (5,6).
Central nervous pain pathways are of interest. The A-delta and C fibers in the peripheral
nerves pass through the dorsal roots and ascend or descend, synapsing on interneurons in
the dorsal horn of the spinal cord (6). A-delta fibers mostly carry mechanical and
temperature-associated pain and terminate in Lamina I of the dorsal horn, activating
neurons of the neospinothalamic tract (5,6). Neospinothalamic tract neurons cross to the
opposite side of the cord as well as ascend on the ipsilateral side, and ascend to the brain
in the anterolateral columns (5,6). Most then synapse in the thalamus—a few terminate in
the reticular areas of the brainstem and in the posterior nuclear group of the thalamus
(5,6). C fibers carrying pain information terminate in Lamiae II and III of the dorsal horn
(substantia gelatinosa)(5,6). Signals pass through one or more neurons in the dorsal horn
then enter Lamina V of the dorsal horn (5,6). These neurons have axons that travel, with
relays, to the brain, terminating in the brainstem, reticular nuclei of the medulla, pons,
and midbrain, the tectal area of the midbrain, and the periaqueductal gray (PAG) around
the aqueduct of Sylvius(6). From the brainstem, pain signals are relayed to the
intralaminar nuclei of the thalamus, the hypothalamus, and other areas of the brain (5,6).
Pain control in the nervous system has three main components. The PAG sends axons to
the nucleus raphe magnus (NRM)( 6,7). The NRM sends axons down the dorsolateral
tracts of the spinal cord (6,7). These axons access the pain inhibitory complex in the
dorsal horn of the cord, so pain can be blocked prior to transmission to the brain (6,7).
Several neurotransmitters are key in pain control. Enkephalins are secreted by neurons of
the PAG and hypothalamus, released at the NRM and at interneurons in the spinal cord
(6,7). In the cord, enkephalins cause presynaptic inhibition of A-delta and C fibers, due to
blockage of calcium channels (6,7). This blockage appears to be fairly longlasting.
Serotonin (5-HT) is secreted by neurons in the NRM that terminate in the dorsal horn of
the spinal cord (6,7). Endorphins are secreted by neurons that synapse onto the
spinothalamic tract to provide postsynaptic inhibition (6,7). Serotonin and norepinephrine
may act synergistically in the cord to block pain transmission (6,7). There are many other
interactions within the brain that act to control and inhibit the transmission of pain
information.
The gate control theory is a widely cited concept, although it does not explain all
acupuncture effects (8). Specifically, signals in large-diameter, rapidly-conducting
afferent fibers carrying nonpainful information regarding pressure, touch, and vibration to
the substantia gelatinosa by synapsying on inhibitory interneurons close the “gate” to
ascending pain transmission traveling along slower fibers, thereby preventing
transmission of that information (8). The A-delta fibers most likely are the “gate-closing”
fibers (9).
Low –frequency stimulation of an acupuncture point activates small-diameter neurons
within peripheral nerves. These neurons then synapse in the dorsal horn of the spinal
cord. By relay, the spinal cord, brainstem, and hypothalamic-pituitary areas are activated
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to release neurotransmitters. These neurotransmitters act to inhibit transmission of painful
stimuli.
Neuroendocrine effects are also achieved via opiate pathways. While the precise
pathways by which internal organs and hormonal activation are affected are not as well
defined as is acupuncture’s effect on pain, the overall concept is that of segmental
association. Each segment is comprised of a dermatome, myotome, sclerotome and
viscerotome (10). While these components may move some distance from each other
during embryonic development, they retain a shared innervation (10). Each part of a
segment can and does affect the other parts. In general, the sclerotome is the most cranial
of the segmental parts, with the dermatome more caudal and the viscerotome most caudal
(9). Stimulation of the skin or muscle of a particular dermatome or myotome can
influence internal organs that have the same segmental innervation via musculo-visceral
and cutaneovisceral reflexes (10).
Visceral pathology is projected to the spinal cord via a number of pathways.
In humans these include sympathetic fibers to spinal segments C8-L2, via the phrenic
nerve to C3-C5, via the pelvic nerves to S2-S4, and via the vagus nerve to the brainstem
and C1-C2 (10).
Multiple other physiologic effects of acupuncture have been documented. These include
vascular effects and effects on the immune system (6).
With acupuncture point stimulation there is initial local vasoconstriction that lasts for
seconds (11). This is followed by a prolonged vasodilation phase that may last up to two
weeks, increasing perfusion to the area (11). Acupuncture has been documented to cause
enhanced humoral immunity, increased WBC count, antibody levels, and phagocytic
activity (12).
3. Traditional Chinese Medicine (TCM) concepts
A complete review of TCM concepts is outside the scope of this article and is available in
other resources ( 3, 13, 14)). However, it is useful to identify particular concepts, as the
terminology is shared in all use of acupuncture in human and veterinary medicine.
Acupoints are arranged on particular channels or meridians, although there are also some
special points outside these guides. The channels have specific names that include those
of particular organs (bladder, gall bladder, heart, etc). These names refer to the TCM
view of the organ, which is not necessarily, completely, or at all connected to the
conventional or Western concept of that organ. When working with acupuncture, it is
important to divorce that connection in one’s mind and associate the TCM names with
the TCM meanings: it is truly a different paradigm.
Qi (pronounced “chee”) is considered the vital force of the body, or by some, it is
considered to be the blood, nerve conduction, and lymph flow (2, 13,14). There are
varieties of Qi, and a variety of functions that it performs. Pathology of Qi is a main
cause of illness or dysfunction in TCM (2, 13).
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The internal organs, and indeed all of creation, are divided into Yin and Yang in TCM.
These are complentary concepts; in fact one really cannot exist except in relation to the
other. Yin is darkness, dampness, female, slow, cold, etc.(2,13) Yang is light, dryness,
heat, male, quickness, etc. (2,13) Imbalance allowing an excess or deficiency of one or
the other in any particular organ system is an underlying cause of illness in TCM.
Traditional Chinese Medicine also utilizes the Five Phase Theory, where each element of
existence is considered part of the cycle of change of five basic elements: Wood, Fire,
Earth, Air, and Metal (2,13). Once again, these are not the actual items they describe, but
concepts of being. There are various cycles that involve these elements, and these cycles
are used for diagnosis and treatment of dysfunction in TCM (2,13).
The understanding of a completely foreign system does not come easily to the Westerntrained mind, but the basic understanding of the concepts is necessary to allow the
acupuncture practitioner to read, communicate, and understand the acupuncture literature,
and can lead to a deeper, or different, understanding of the practice.
4. Use of acupuncture in reproduction
Unfortunately, there is a shortage of scientific study published, particularly in the English
language. However, some useful studies are available and will be discussed here.
4.1
Fertility effects-male
The use of acupuncture in men with idiopathic infertility was evaluated, with twentyeight men in the treatment group and twelve men in the untreated control group (15).
Treatment was performed twice weekly for five weeks. Samples were evaluated
quantitatively using transmission electron microscopy. Significant improvement was
seen in percentage and total number of structurally normal spermatozoa (15). However,
specific sperm pathologies remained statistically unchanged (15).
In a prospective controlled study of men with subfertility sixteen patients were treated
twice a week for five weeks, while sixteen men were untreated (16). Semen evaluation
was performed prior to and one month post treatment. Improvement in total functional
sperm fraction, percentage of viable spermatozoa, total motile spermatozoa per ejaculate
and axonemal integrity were significantly improved.(16) There was a high correlation
between axonemal integrity and sperm motility in this study (16). Additional studies
reported similar improvement in men with impaired fertility or semen abnormalities
(17,18,19).
4.2
Fertility effects-female
Definitive work is lacking, but studies suggest that the neuropeptides released due to
acupuncture stimulation may act on gonadotropin releasing hormone (GnRH) (20). One
study showed improvement in women with uterine artery blood flow impedance when
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treated with EAS twice weekly for four weeks, however no control group was included
(21).
Another study reported on 34 women with ovulatory dysfunction, treated with
acupuncture at BL 18 and 23, CV 3 and 4, and SP 6 (22). Patients were treated on varied
schedules and no controls were included. Marked improvement was seen in 35.29% of
patients with some improvement in 82.35% of patients (22). A recurring theme in
published reports is the lack of controls and strict regulation of methods and data
collection.
In women undergoing assisted reproduction technology, acupuncture improved
pregnancy rate when performed 25 minutes prior to and after embryo transfer, with
pregnancy rate of 26.3% in controls and 42.5% in the acupuncture group (23).
Some animal studies are available as well. One study evaluated repeat-breeder dairy
cattle previously treated with GnRH with a 30% success rate (24). Cows and heifers that
did not respond to GnRH were treated with aquapuncture (5-10 ml of 50% glucose
solution) at points BaiHui and Shenpeng (24). The study reports that “most” animals
showed signs of estrus within fourteen days of treatment (24). After artificial
insemination 77.7% had elevated progesterone and 66.6% were palpated pregnant per
rectum (24). However, actual delivery occurred in only 44.4% (24).
A study of anestrus sows compared injection of GnRH with acupuncture at points on the
back (treatment points) and points on the forelegs (sham points) (25). Three of four sows
treated with acupuncture at appropriate points entered estrus, while only one of four did
so out of each of the other two groups (25). In addition, the sows in the actual treatment
group also developed a rise in progesterone (25).
No scientific studies on companion animal reproduction published in the English
language are currently available. While this author believes it is likely that acupuncture
can be helpful in cases of infertility due to the neurophysiology involved, no
recommendations can be made based on scientific study. The use of particular points can
be selected based on TCM principles or from studies in humans and other species.
4.3
Acupuncture in pregnancy and parturition
Caution is recommended in the routine use of acupuncture during pregnancy, particularly
in the first and trimesters (26). Needling the caudal abdomen or back and needling of
distal points on the legs is particularly contraindicated, due to the risk of possible
miscarriage (26). This introduces the idea of possible use of acupuncture as an adjunctive
treatment in medical abortion in the bitch, an area which should be explored. Particular
study of the use of acupuncture during pregnancy is recommended prior to undertaking
its use in treatment of routine problems in pregnant animals.
Acupuncture has been successfully used to minimize severe morning sickness
(hyperemesis gravidarum) in women (27). Acupoint PC6 was utilized in a prospective
placebo controlled study, where a sham acupoint was used as a control. Although the
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numbers were small, the efficacy of acupuncture at PC6 in controlling the hyperemesis
was 90%, acupressure at PC6 was 63.6% with efficacy of sham acupuncture 12.5% and
sham acupressure 0% (27). This may be of use in treating bitches that have severe
anorexia and vomiting at 3-4 weeks of gestation. The mechanism of action is believed to
be the increase in hypophyseal secretion of beta-endorphins and ACTH causing
inhibition of the chemoreceptor trigger zone and vomiting center (28).
Moxibustion has been successfully used to rotate breech pregnancies in women prior to
parturition. In a randomized study of 226 women, the patients treated with acupuncture
and moxibustion at BL 67 had a cephalic presentation in 53.6%, whereas the control
group, observed only, had a cephalic presentation in 36.7% (29). Similar results were
seen in a randomized study of 67 women, with breech correction present in 76.4% and
only 45.4% of the control group (30).
Acupuncture has been used to induce cervical ripening and labor in women (31)
Acupoint BL 67 has been used to accelerate cervical dilation with reported 75% success,
although details of the study parameters are lacking (32). Electroacupuncture stimulation
of LI 4 and SP6 resulted in increased frequency and duration of uterine contractions,
although again study parameters are not adequately stated (32). This author has had
success with EAS at these and additional points to strengthen uterine contractions during
labor in the bitch, equal to or greater than that achieved with oxytocin and calcium
administration when observed on a tocodynomometer (unpublished data), although the
case numbers are small. The use of EAS in this manner is more labor and time intensive
than the conventional administration of pharmacologic agents. Use of acupuncture during
labor in women reduced the use of meperidine for pain management from 37% to 11%,
indicating efficacy in moderating the pain of parturition (33). In a randomized tiral of 46
women, acupuncture significantly decreased the need for epidural anesthesia from 22% in
the control group to 12% in the treated group, with no adverse effects reported (34). In a
randomized study of 75 women in labor, acupressure at SP6 reduces labor pain scores at
all time points and significantly decreased the total labor time in treated women (35).
4.4
Lactation effects
A case report noted that a woman treated with acupuncture for post-mastectomy pain
developed lactation in the remaining breast, although she had not previously lactated for
four years (36). The acupuncture treatment she had received included SI 11, a point used
in TCM to promote lactation (36). Quantitative analysis has demonstrated an increase in
the production of prolactin and oxytocin following acupuncture at SI 11 in rats (37).
This author has had dramatic success in stimulating milk production and milk letdown in
postpartum bitches using acupuncture at SI 11 and LI 4. Other points that have been
recommended, depending upon presentation of the patient and TCM evaluation, include
ST 36, SP6, SI 1, BL 17, 20 and 23 (38).
4.5
Neonatal resuscitation
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The use of acupoint GV 26 for resuscitation and stimulation is widely practiced. Special
training and needles are not required for success, as the point, located midline on the
philtrum at the junction of its dorsal and medial third, is readily accessed and a 25 g
needle can be utilized. Stimulation is provided in a strong manner, with a pecking motion
(39). Stimulation of GV 26 increases blood pressure and stimulates the brain inspiratory
centers (39).
In summary, while published scientific data on the efficacy of acupuncture in small
animal reproduction is lacking, there is both historical information and scientific data in
other species that support its use. Study of this modality in companion animal
reproduction is needed and encouraged, and its use may be very helpful in a variety of
clinical presentations.
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