An Introduction To Veterinary Acupuncture
By Nina Malik, DVM
(Continued from cover page)
… one of the oldest medical textbooks in the world, dating back over 2,200 years ago in China. Theories of circulation and pulse character were postulated in China over 4,000 years before Western medicine had concepts about them. The first veterinary acupuncture text was written in China around 650 BC. As a practitioner with a strong Western sense of medical skepticism, acupuncture's lineage of thousands of years of experiential healing have helped to build my confidence in the modality. I have often challenged myself that if I can prescribe a supplement like glucosamine chondroitin for joint disease, which has anecdotally been utilized in Western human medicine for at best 50 years, why not then turn to acupuncture's thousands of years of history? As the public hears of athletes -- like all-around gymnastics' gold-medalist Nastia Lukin -- getting weekly acupuncture treatments, it is no wonder that there has been a push for complementary therapies to be further incorporated into veterinary medicine as well.
The Eastern Framework
Theories of traditional Chinese medicine describe an energy force (Qi) which runs through the body. When the polar opposite energies of Yin and Yang merge, Qi is created. The flow of Qi influences the health of an animal. If the flow of Qi is insufficient, unbalanced, or obstructed, then Yin and Yang become imbalanced and disease results. Qi travels in meridians or channels in the body. The acupuncture points are specific locations where the meridians come to the surface of the skin and are easily accessible. By needling specific points, the acupuncturist can help to restore balance to the body and allow it to heal itself. In this way, acupuncture can serve as symptomatic treatment for illness while also working at the root of disease. Many of the veterinary acupuncture points that are used by modern veterinarians are based on a transpositional system created from human acupuncture charts. Anatomical landmarks, as well as body measurements, are used to help find the acupuncture points in companion animals.
The Western Framework
Anatomy of Acupuncture Points
It has been shown that acupuncture points are not random points on the body. They are located at areas of low electrical resistance and high electrical skin conductance. Many acupoints can be found within palpable depressions on the body. When acupuncture points are "dissected," bundles of free nerve endings, small arterioles and veins, lymphatic channels, and numerous mast cells are found. Approximately 70% of acupuncture points correspond to known trigger points in the body and many correspond with motor points. Understanding the anatomy of acupuncture points is one of the first bridges back to a more Western framework of explaining how acupuncture may have the effect it does in the body.
Mechanism Of Action
One of the first questions that arises when a complementary therapy like acupuncture is considered by the veterinary community is "how does it work?" There is compelling evidence that acupuncture activates the endogenous pain inhibitory system in the body, produces segmental analgesia, has local inflammatory effects, and provides relief from trigger points. There are also theories of how acupuncture interacts with the autonomic nervous system to affect viscera. The following is an attempt to present some of the current proposed mechanisms of action of acupuncture. The purpose of this is two-fold. First, it is to demystify the "magical basis of action" of acupuncture into a more mechanistic one. Second, it is helpful in considering the indications for acupuncture therapy.
Effects Of Acupuncture On The CNS
Stimulation of an acupuncture point activates the A delta pain fibers, which mediate touch and pressure sensation. These fibers synapse in the dorsal horn of the spinal cord and subsequently activate three CNS regions: the spinal cord, the brainstem, and the hypothalamus-pituitary. These regions release neurotransmitters -- such as endogenous opiates -- to block pain messages.
Endogenous Pain Inhibition
As explained above, acupuncture is thought to stimulate the spinal cord, brainstem, and hypothalamus-pituitary through activation of the A delta fibers. Once stimulated, the hypothalamus and pituitary have their effects through beta-endorphin, which is released into the blood and CSF. Activation of the brainstem stimulates descending norepinephrine and serotonergic inhibitory fibers, which travel in the dorsolateral tract of the spinal cord and synapse on dorsal horn interneurons. These effects trigger the release of enkephalin and dynorphins from segmental interneurons, which then bind to opiate receptors on pain afferents. This causes presynaptic inhibition of both the A delta nerve fibers and the slower unmyelinated C fibers, which are associated with temperature, crude touch, aching, burning, and chronic pain. This mechanism may also suppress the release of substance P from the afferent pain axon resulting in inhibition of pain impulse transmission to the brain for conscious perception. The fact that Naloxone reverses acupuncture analgesia has been used as evidence that acupuncture effects are mediated through such an endogenous opiod neural loop.
Segmental Analgesia
Segmental analgesia can be evoked by high-frequency, low-intensity stimulation of acupuncture points. This may be achieved with electroacupuncture (i.e.100 Hz), which is described later. Analgesia is localized, rapid in onset, and ceases soon after stimulation has stopped. High-frequency, low-intensity electrical stimulation is thought to activate only the dynorphin (not the enkephalin or beta-endorphin) synapses in the spinal cord. There is direct stimulation of serotonin and norepinephrine in the brainstem and mediation by GABA in the spinal cord in this pathway.
Local Tissue Effects Of Acupuncture
Insertion of the acupuncture needle induces microtrauma triggering a local inflammatory reaction in the tissue. This activates Hageman's tissue factor XII, which in turn stimulates a local coagulation and complement cascade (involving plasminogen, protein kinins, prostaglandins, mast cell degranulation, histamine, heparin, proteases, and bradykinin). The high concentration of nerve endings and microvasculature at the acupuncture point is considered to enhance the response. After a short vasoconstrictive phase, a vasodilatory phase (lasting two minutes to two weeks) ensues. There are several time-dependent phases -- including vasodilation, nociceptive potentiation, chemotaxis, tissue repair, and inactivation of the reaction -- that take place in the tissue. This results in improved local tissue perfusion, increased local immune responsiveness, and muscle and tissue relaxation.
Autonomic Nervous System Feedback Loop
The viscerocutaneous reflex describes a mechanism by which diseased organs can refer pain, sensitivity, or muscle contraction to acupuncture or trigger points. A well-cited example of this from human medicine involves McBurney's point, an area in the lower right abdominal quadrant, which becomes painful in appendicitis patients. Likewise, a reverse loop, the cutaneovisceral reflex has been described. According to this theory, the somatic nerve ending of a muscle would be stimulated by the insertion of a needle into a paravertebral muscle at a myotome segmental level associated with muscular pain. This would trigger an afferent impulse to the dorsal horn of the spinal cord followed by stimulation of the contralateral anterior hypothalamus. The result would be activation of a somato-autonomic reflex which ultimately activates the cholinergic vasodilator nerves to spastic muscles.
Trigger Point Therapy
A trigger point is a hyperirritable locus within a taut band of skeletal muscle or its associated fascia. Trigger points have also been described in skin, scars, tendons, joint capsules, ligaments, and periosteum. The point is usually painful on palpation and causes referred pain to other areas of the body. A latent trigger point may produce stiffness and decreased joint range of motion. Acupuncture needling of trigger points may mechanically disrupt the abnormally functioning contractile elements or nerve ending forming part of the feedback loop. Trigger points can be treated with dry needling or injection of lidocaine. Trigger points often have typical distributions in the dog.
Acupuncture Modalities
The most common of modalities is dry needling of acupoints with sterile, single-use needles. Aquapuncture involves injecting dilute solutions into acupuncture points. This often helps to prolong the effect of acupuncture. Solutions that may be injected include Vitamin B12, saline, or lidocaine, for example. The effects of acupuncture may also be intensified or the duration of effect lengthened by heating or electrically stimulating the needles. Heating the needles is called moxibustion and involves the burning of Artemesia vulgaris over acupuncture points. Electroacupuncture is the practice of electrically stimulating the needles at various frequencies depending on the treatment goal. This modality is often utilized in a conventional TENS-like fashion to "retrain" muscles, for certain neurologic diseases, or for enhanced pain control. Finally, infrared light therapy, also called Lacer therapy, involves imparting infrared light energy at various frequencies to stimulate cells and acupuncture points. This method is helpful in patients who are needle-phobic or for points not easily reached in veterinary medicine. Anecdotally, this has also been a useful treatment for eye disorders and non-healing skin wounds.
Indications For Acupuncture
The proposed mechanisms of action and anatomy of acupuncture points described above were presented to facilitate an understanding of why acupuncture is described as being indicated for numerous pain, musculoskeletal, neurologic, and inflammatory conditions. Although acupuncture is widely recognized for its analgesic and musculoskeletal effects, it is possible to see how it can also affect the viscera, immune system, and beyond. Anecdotally, acupuncture has been used as a successful complementary therapy in the following conditions. The following list is not exhaustive:
Pain
Musculoskeletal disease including post-operative orthopedic surgery, osteoarthritis, trigger point therapy, and joint dysplasia
Neurologic disease including intervertebral disk disease, FCE, seizures, neuropathies, vestibular disorders, and to improve the comfort of patients with degenerative myelopathy
Gastrointestinal disorders causing nausea, vomiting, diarrhea, constipation, and abdominal pain
Dermatologic disorders such as allergic dermatitis, chronic skin disease, and otitis externa
Behavioral Problems
Cardiovascular and respiratory disease including rhinitis, sinusitis, bronchitis, chronic coughing, circulatory disorders, and asthma
Urogenital disorders such as urinary incontinence, urinary tract infections, and chronic kidney disease
Immune stimulation in immunosuppressed individuals and for an anti-pyretic effect
Oncology patients to reduce the side effects of chemotherapy and improve overall vitality of the patient
Response To Acupuncture
Acupuncture on two skunks with bridging spondylosis and back pain.
Acupuncture is not painful. The patient feels the needle only as it goes through the skin. Once the needle is in place, the patient may feel a warmth, heaviness, or tingling. Many animals relax and fall asleep with their needles in place. The response to acupuncture is individual and the effects of treatment are often cumulative. Therefore, a course of treatment over a period of weeks is recommended. Acupuncture can also offer geriatric patients with chronic debilitating conditions a treatment option when the end of the line has been reached with Western medical therapies. Traditional Chinese medicine provides a therapeutic framework continuum where Western medicine often stops. This can offer quality of life at an extended lease to patients that may have had no other option but euthanasia. The risks of acupuncture are few and the potential benefits are great enough to deserve a significant role in integrative veterinary medicine.