546 Canine Sports Medicine and Rehabilitation
Acupuncture overview
Acupuncture is the insertion of fine, sterile
needles into specific acupuncture points to
create a physiological response. These physio-
logical responses are due to stimulation of both
the central and peripheral nervous systems.
Acupuncture stimulation releases endogenous
substances such as beta-endorphins, dynorphins,
enkephalins, serotonin, epinephrine, GABA,
cortisol and various hormones (Soligo et al.,
2013). The earliest scientific studies done on
acupuncture focused on its analgesic effects.
In the late 1970s researchers discovered that
acupuncture stimulation led to an increased
concentration of endogenous opioids in the
serum and cerebral spinal fluid (Pan et al., 1984;
He, 1987). Additional studies showed that
naloxone, an opioid antagonist, blocked the
effects of acupuncture and decreased the pain
threshold in acupuncture subjects (Mayer et al.,
1977). These were the first studies showing that
endogenous opioids played a role in the mecha-
nism of action of acupuncture analgesia.
Acupuncture stimulation increases the blood
concentration of the serotonin precursor free
tryptophan (Costa et al., 1982). Others have
shown an increase in serotonin in the central
nervous system (CNS) after acupuncture stimu-
lation (Zhong, 1989). Beta-endorphins stimulate
serotonergic nerves within the descending tract
to release serotonin (He, 1987). It is speculated
that acupuncture analgesia involves seroton-
ergic neurons since acupuncture releases beta-
endorphins, which in turn releases serotonin.
Acupuncture analgesia may be related to one
or more of the four phases of pain perception:
insult from a noxious stimulus, transduction of
the painful stimulus via electrical signals, trans-
mission of the painful stimulus into the spinal
cord, and perception of pain by the higher brain
centers and somatosensory cortex. One hypoth-
esis proposes that acupuncture stimulation can
block perception of pain before it reaches the
CNS. This is based on Wall and Melzack’s gate
control theory of pain perception (Melzack &
Wall, 1965; DeLeo, 2006). Acupuncture stimu-
lates A-beta and A-delta fibers to rapidly carry
information to the spinal cord, synapsing with
inhibitory interneurons to close the gate before
ascending pain impulses arrive from the C fibers.
This prevents pain impulses from reaching the
higher brain centers and blocks conscious
perception of pain. Regional acupuncture anal-
gesia is also speculated as A-delta fibers are
transmitted cranially and caudally within spi-
nal segments before entering the dorsal horn
gray matter (Steiss, 2001). Acupuncture also
activates the descending pain control pathway
modulating nociceptive signals at the level of
the brain and spinal cord (Murotani et al., 2010;
Silva et al., 2011). Acupuncture has also been
shown to alleviate inflammatory pain in rats
and human models, thereby reducing inflam-
matory mediators such as lipopolysaccharides,
interleukin 6 (IL-6), IL-1β, and tumor necrosis
factor alpha (TNF-α) (Jeong et al., 2003; Yim
et al., 2007; Zhang et al., 2012).Acupuncture pointsDogs have approximately 360 acupuncture
points located throughout the body. There are
four types of points depending on their associ-
ated neural structures: Type I motor points,
Type II midline points, Type III nerve or nerve
plexus points, and Type IV muscle–tendon
junction points. Motor points make up 67% of
all points, and are located in areas where nerves
penetrate a muscle. SI-9 is located at the junc-
tion of the deltoideus and the long head of the
triceps brachii, where the axillary and radial
nerves emerge. Type II points are located on the
superficial nerves on dorsal and ventral mid-
lines. Bai-hui lies in the depression between the
spinous processes of the 7th lumbar and the 1st
sacral vertebrae on the dorsal midline and it is
supplied by the dorsal branch of the 7th lumbar
nerve. Type III points are located at high-den-
sity loci of superficial nerves and nerve plex-
uses. GB-34 is the point where the common
peroneal nerve divides into the deep and super-
ficial branches. Type IV points are located at
muscle–tendon junctions where Golgi tendon
organs exist. BL-57 is located at the junction of
the gastrocnemius muscle and the common cal-
canean tendon (Gunn et al., 1976; Gunn, 1977).
Most acupuncture points are located in areas
of low electrical resistance and high electrical
conductance (Brown et al., 1974; Reichmanis et al.,
1975; Urano & Ogasawara, 1978). Histological
studies reveal that acupuncture points are
located in areas where there are free nerve