Acupuncture has evolved into a medically appropriate, scientifically driven treatment for pain in companion animals.
— Huntingford and Petty
Recently an interesting review came out. This article gives a brief overview of how acupuncture works and can be used for pain relief in animals.
I’m going to do my best to give you an understandable summary of this article. Of course, this blog post is a somewhat simplified version of the original article and there are even more mechanisms and effects than the ones I will describe here.
In addition, we do not yet know everything and there are most likely many more effects of acupuncture that have not yet been determined with research.
Acupuncture is a very effective method of pain relief. It is used alongside conventional therapies or as an alternative to conventional treatments. With conventional treatments, for example, you can think of pain medication.
Contrary to what many people still think, there is now a lot of scientific evidence for the effectiveness of acupuncture in various conditions, including its use for pain.
The latest guidelines for pain management in companion animals from the WSAVA (world small animal veterinary association) also mention acupuncture as a non-pharmaceutical treatment for pain.
From a TCVM perspective, acupuncture is used to restore the balance of Qi. From a Western perspective, it looks at restoring the physiological balance and various mechanisms that are activated by the acupuncture needles to achieve pain relief.
There are mechanisms that occur at each acupuncture point, but the different acupuncture points also have different effects. For example, some will affect the immune system, other points can affect, for example, the autonomic nervous system, the organs, the brain, the lymph or the nerves and muscles.
To understand how acupuncture works, you will need to have a basic understanding of how pain works. Let me explain briefly here. Pain occurs in several steps:
The first step is when damaged cells release inflammatory mediators. Special pain receptors, called the nociceptors, convert the signals from these inflammatory mediators into an electrical signal for the nerves.
Supplying nerves (afferent nerves) pick up this electrical signal and send it to the spinal cord. There are different types of nerves that can do this and each nerve has a slightly different effect. The A-delta nerves, for example, provide an acute sharp pain and the C nerves provide a slower, more burning dull pain. The C nerves are also responsible for the development of chronic pain.
The impulse arrives in the spinal cord. Here, several things can happen with this impulse. The impulse can be inhibited or amplified. Inhibition provides reduction of pain, reinforcement for exacerbation of pain. From the spinal cord, the signal is also transmitted to the brain.
The brain will interpret the impulse/pain signal and ensure that you actually feel it. This is a complicated process in which centers responsible for emotions also play a role. How the pain is interpreted depends not only on the signal itself but also on the state of the body, previous pain experienced, the emotional state of the individual and a number of other factors. How pain is experienced is therefore different in each individual.
Well, now that we know how pain arises, let’s look at how acupuncture can affect pain. Acupuncture works on different levels: locally, in the spinal cord and in the brain.
As soon as you insert an acupuncture needle into an acupuncture point, local effects arise. The fibers of the tissue wrap around the needle and this affects the local cells, nerves and blood vessels. The cells, nerves and blood vessels secrete various substances that have different effects.
The microtrauma caused by the needle also activates the local healing cascade: the coagulation cascade, the complement cascade and mast cells degranulate. How all these cascades work exactly does not matter. The end result is that locally blood flow increases and the local defenses are stimulated, reducing pain and inflammation.
Puncturing the acupuncture point also causes a local excretion of opioids which reduce pain.
The effect of acupuncture on the spinal cord is versatile and complicated. One of the mechanisms that has been extensively investigated is the “gate control theory”.
Imagine that there is a gate in the spinal cord that can open and close to send signals to the brain. I explained above that there are different types of nerves that transmit pain signals to the spinal cord. This theory assumes that by stimulating a specific type of pain nerve (the A-beta fibers) you stop transmitting the signals of other pain nerves (the C and A-delta fibers). In other words, stimulating certain nerves causes this gate to transmit pain signals to close. As a result, the animal feels less pain.
In addition to this mechanism, there are many other mechanisms that influence the various pain signals. It is interesting to know that acupuncture also affects the organs due to the effect at the level of the spinal cord and can thus influence the function of organs.
The third level that acupuncture affects is at the level of the brain. Less is known about this level than about the previous two levels. MRI studies done with humans show that stimulating acupuncture points activates or makes specific areas in the brain less active. For example, we know that certain areas that reduce pain become more active after acupuncture. We also know that endorphins are released in response to acupuncture. Endorphinen provide a reduction in pain.
Different acupuncture points have different effects at different levels. As an acupuncturist you use a combination of points to obtain the desired effect at all levels.
In chronic pain, changes occur in the nervous system that contribute to maintaining and exacerbating this pain. Acupuncture can prevent or reverse these changes.
Finally, the article gives a number of examples of studies that have shown that acupuncture can be used effectively to reduce pain in cruciate ligament problems, hip dysplasia and hernias, among other things.
Huntingford, J.L. and Petty, M.C. (2022) Evidence Based application of acupuncture for pain management in companion animal medicine. Bold Sci 9: 252.