Acupuncture Overview

Acupuncture is the insertion of fine, sterile needles into specific acupuncture points subsequently creating a physiologic response. These physiologic responses are due to stimulation of both the central and peripheral nervous systems. Acupuncture stimulation releases endogenous substances such as β-endorphins, dynorphins, enkephalins, serotonin, epinephrine, gamma-aminobutyric acid (GABA), cortisol, and various hormones. 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 mechanism 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 after acupuncture stimulation (Zhong, 1989). β-Endorphins stimulate serotonergic nerves within the descending tract to release serotonin (He, 1987). It is speculated that acupuncture analgesia involves serotonergic neurons since acupuncture releases β-endorphins, which in turn induce release of 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, transmission of the painful stimulus into the spinal cord, and perception of pain by the higher brain centers and somatosensory cortex. One hypothesis proposes that acupuncture stimulation can block perception of pain before it reaches the central nervous system. This is based on Wall and Melzack’s gate control theory of pain perception. Acupuncture stimulates 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 analgesia is also speculated as A-delta fibers are transmitted cranially and caudally within spinal segments before entering the dorsal horn gray matter (Smith, 1994b).

Acupuncture Points

Dogs have approximately 360 acupuncture points located throughout the body. There are four types of points depending on their associated neural structures. Type I (motor points) make up 67% of all points, and are located in areas where nerves penetrate a muscle. For example, SI-9 is located at the junction of the deltoideus and the long head of the triceps brachii, where the axillary and radial nerves emerge. Type II (midline) points are located on the superficial nerves on dorsal and ventral midlines. For example, 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 (nerve or nerve plexus) points are located at high-density loci of superficial nerves and nerve plexuses. For example, GB-34 is the point where the common peroneal nerve divides into the deep and superficial branches. Type IV (muscle-tendon junction) points are located at muscle-tendon junctions where Golgi tendon organs exist. For example, BL-57 is located at the junction of the gastrocnemius muscle and the common calcanean 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 endings, arterioles, lymphatic vessels, and aggregations of mast cells (Pan et al., 1986). Due to their anatomical location, many different local effects occur with acupuncture point stimulation. These include an increase in local blood flow and circulation; release of Hageman’s Factor XII, which activates the clotting cascade, complement cascade, and release of plasminogens and kinins; mast cell degranulation, which releases histamine, heparin, and proteases; release of bradykinin, which leads to vasodilation; and production of local prostaglandins, which leads to smooth muscle relaxation (Omura, 1975; Kendall, 1989a). The vasoactive effects that occur with acupuncture stimulation follow a specific sequence. There is an initial short vasoconstriction phase (lasting 15–30 seconds), followed by a quasi-control state (lasting from 10 seconds to 2 minutes), and a final vasodilation phase (lasting from 2 minutes to 2 weeks) (Omura, 1975). This results in an enhanced local tissue immune status, improved local tissue per­fusion, and muscle and tissue relaxation. Pain relief occurs as a result of improved perfusion and reduction of muscle spasms caused by local effects of acupuncture stimulation and somatovisceral reflexes (Smith, 1994a).

Methods of Acupuncture Point Stimulation

There are nine ways to stimulate acupuncture points: dry needle, electroacupuncture, aquapuncture, acupressure, laser acupuncture, moxibustion, hemoacupuncture, pneumoacupuncture, and gold implantation (Xie & Preast, 2007). Dry needle is defined as the insertion of acupuncture needles into acupuncture points. These needles vary in length (1/4, 1/2, 1, 1.5, and 2″) and gauge (28, 30, 32, 34, and 36 gauge), and they are typically left in place for approximately 20 minutes. Dry needle is the most commonly used acupuncture technique in dogs.

Electroacupuncture is the attachment of elec­trical leads to dry needles and connection to an electroacupuncture unit. The unit can be set to a variety of frequencies and each frequency stim­ulates a different pathway in the nervous sys­­tem. Low-frequency (1–20 Hz) electroacupuncture predominantly stimulates A-delta fibers and releases β-endorphins and met-enkephalins. High-frequency (100 Hz) electroacupuncture predominantly stimulates C fibers and releases dynorphins. Even higher frequency (200 Hz) electroacupuncture stimulates the serotonergic fibers and releases serotonin and norepinephrine (Melzack & Wall, 1965; Kendall, 1989b). Canine patients are frequently treated with a combination of dry needle and electroacupuncture.

Aquapuncture is the injection of a sterile liquid directly into acupuncture points. The pressure of the liquid induces stimulation of acupuncture points until it is absorbed. The most commonly used injectable liquids include saline, vitamin B₁₂, and lidocaine.

Acupressure is the application of manual pressure on acupuncture points for a period of 1–5 minutes per point. This is a safe and easy technique to demonstrate and instruct owners to perform at home.

Low-level laser therapy can be applied directly on acupuncture points to induce stimulation of the points. Treatment can be done with either a Class 3B or a Class 4 therapeutic laser at routine settings for the individual body region.

Moxibustion is performed using the dried herb Artemisia rolled into a cigar shape and burned 1/2″ over the acupuncture point without touching the skin. This stimulates acupuncture points through a warming technique and is typically used on patients with chronic arthritis that is worse in cold weather.

Hemoacupuncture has two forms of stimulation. The first form involves the withdrawal of a small amount of blood from acupuncture points located directly on blood vessels. For example, Tai-yang is located on the transverse facial vein just lateral to the lateral canthus of the eye. This technique is primarily used for febrile diseases. The second form involves the injection of the patient’s blood into acupuncture points. This technique is used for autoimmune diseases.

Pneumoacupuncture is the injection of air into the subcutaneous space in areas where there is muscle atrophy. The theory behind this technique is that the air puts pressure on the acupuncture points and stimulates them until the air is absorbed.

Gold therapy is the injection of sterile gold, in the form of a small wire or bead, directly into acupuncture points. The gold creates an ionic change in the tissues that stimulates the points for a prolonged period of time.

Acupuncture Point Selection

Local points are those located directly in the area to be treated, and they are selected largely to treat pain. For example, ST-36 is a local point for the stifle as it is located just distal to the tibial plateau in the cranial tibial muscle. Distal points are located either distal or caudal to the area to be treated, and they are selected for the patient that feels too much pain at the local site and/or to draw edema or swelling from the local site. For example, LIV-3 is located between the 2nd and 3rd metatarsals proximal to the metatarsophalangeal joint, so quite distal to the stifle and is commonly used to treat stifle pain. Another option is to select points proximal/cranial and distal/caudal. For example, a patient with intervertebral disk disease (IVDD) at T13-L1 can be treated with BL-20 (lateral to the caudal border of the dorsal spinous process of T12) and BL-23 (lateral to the caudal border of the dorsal spinous process of L2).

It is important to know the anatomical location and clinical indication of acupuncture points to make an appropriate therapeutic point selection. Since there are approximately 360 acupuncture points, there are many options for point selection for individual conditions. Points that are most commonly used in veterinary medicine are selected for their acceptance by animal patients (Table 22.1) and their ease of anatomical location (Table 22.2) (Xie & Preast, 2007). Points along the neck, back, hips, and shoulders are commonly used in dogs as they are well tolerated due to their location in large muscle groups. Points located in areas with smaller muscles, such as the elbows and feet, are less well tolerated by the canine patient.

Table 22.1 Acupuncture points for specific conditions

Adapted from Xie & Preast (2007).

Table 22.2 Anatomical locations of acupuncture points

Adapted from Xie & Preast (2007).

Integrating Acupuncture Into Sports Medicine and Rehabilitation Therapy

Acupuncture has many applications in sports medicine practice including its use for performance and endurance enhancement, as well as treating con­ditions to which canine athletes are prone such as muscle spasms, trigger points, osteoarthritis, IVDD, and nerve damage. Acupuncture improves endurance and physical performance, and helps to regulate heart rate and blood pressure (Ehrlich & Haber, 1992). Treatment is typically performed 2–5 days before a competition. Acupuncture is also useful after a competition to alleviate pain or stress on the musculoskeletal system. It is important for the athlete to be cooled down and relaxed before doing an acupuncture treatment. Generally, acupuncture is done approximately 2–4 hours after performance; however, it is still effective if initiated the day after a competition. Acupuncture points used for performance enhancement include ST-36, LI-10, CV-4, CV-6, BL-24, BL-26, LI-4, and LIV-3.

Acupuncture is a useful modality to integrate into a rehabilitation program due to its analgesic properties and nerve stimulation effects. Many patients that receive rehabilitation therapy have pain that might hinder their ability to perform physical activity. By decreasing or eliminating pain, acupuncture allows more aggressive rehabilita­­tion treatments to be instituted. Acupuncture can be administered as the final step in the rehabilitation program. For example, a patient with cranial cruciate ligament rupture might receive laser therapy, massage, underwater treadmill, and exercises such as sit to stands. This patient would benefit from acupuncture therapy at the end of the exercises once they have cooled off. For these patients, acupuncture therapy can be given once to twice a week. A patient with IVDD would likely receive a rehabilitation program including physio ball work, isometric contractions, assisted walking with slings, toe pinches, ear scratches, neuro­muscular electrical stimulation, and underwater treadmill. Because acupuncture can promote nerve regeneration (La et al., 2005), it is indicated for these patients, and it is commonly used 1–5 days per week depending on the grade of disk disease. Acupuncture is not only beneficial for pain management and nerve regeneration, but it also has calming/sedating effects which are useful for patients that need to be cage-rested (Kim, 2006). Acupuncture points used for their calming/sedating effects include GV-17, GV-20, GV-21, An-shen, and, HT-7.

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