Application Of Acupuncture And Hydrotherapy In The Management Of Chronic Pain
Introduction
Joint pain that is chronic in nature is associated with a wide range of conditions, commonly affecting the stifles, hips and elbows. Persistent joint pain often causes altered weight bearing to protect the affected limb from further pain with pain management therefore said to be a key component of veterinary medicine. This has been shown to have an overall effect on locomotion with Gillette and Angle (2014) associating pain with a reduction in stride length.
Introduction to Therapeutic Techniques
Research has documented that the short term use of conventional analgesics in veterinary medicine including Tramadol may be a viable option with Akhtardanesh et al. (2014) reporting no significant effect on the functioning of the liver and kidneys. Contrary to this, it is also evident that the long term use of conventional analgesics is not a feasible option, with Molina et al. (2014) associating this with adverse effects including chronic gastritis. Therefore, many people turn to complementary and alternative medicines for the treatment of chronic pain in human medicine, and it is quite often for similar reasons for animal medicine (Bloom et al. , 2000).
Despite this, there is a solution, with Stener-Victorin et al. (2004), Chernyak and Sessle (2005) and Haltrecht (1999) having reported that when used in addition to conventional veterinary medicine, both acupuncture and hydrotherapy effectively reduce pain whilst increasing quality of life and should therefore should be considered as valid complementary treatment options. In fact it can be said that no therapy should be viewed as an alternative to conventional medicine, especially considering their practice should be guided by a veterinary surgeon as specified in the Veterinary Surgeons (Exemptions) Order 2015.
Acupuncture
The research of Magalhães-Sant’Ana (2019) considers acupuncture to be one of the major alternatives to conventional veterinary medicine. It is thought that veterinary acupuncture is most effective in the management of musculoskeletal pain stemming from conditions including osteoarthritis (Lindley, 2006), where its practice is supported by a growing body of scientific evidence supporting its efficacy along with its minimally invasive nature with minimal risk of adverse effects.
The procedure involves the insertion of a thin, sterile needle into a series of specific bodily points, with the mechanisms behind this described by Fry et al. (2014) as being complex and requiring further refinement. Additionally, the accurate placement of the needle and the acupuncture-related technique and placebo used can greatly affect the outcome of a trial.
Studies including those by Fox and Downing (2014); Kapatkin et al. (2006) and Mittleman and Gaynor (2000) have found acupuncture to activate the complex neuro-hormonal systems within the body, resulting in the release of substances such as endorphins, enkephalins, and serotonin, ultimately producing analgesia (pain relief).
Hydrotherapy
Hydrotherapy is the practice of water based exercise, where its properties are advantageous in providing safe and comfortable exercise (Tomlinson, 2012) as part of a multi-modal treatment plan. The buoyancy of water has been demonstrated to reduce weight bearing stresses on bones, muscles and joints, enabling the earlier intervention of this intensive form of rehabilitation with minimal risk of increasing pain or overloading injured tissues, ultimately reducing the pain associated with impact loading exercises. It is also thought that hydrostatic pressure leads to a reduction in pain perception, with Matsumoto et al. (2017) and Wild (2017) showing warm water to provide an evidenced level of pain relief whilst possibly also reducing stiffness and improving function in patients with osteoarthritis of the knee.
Whilst there are many forms of hydrotherapy, exercises performed in a pool or underwater treadmill are the most common (Prankel, 2008). In canine hydrotherapy, the pool appears to be the equipment of choice, with many deeming this to be a more versatile approach, enabling a hands-on treatment, and the assessment of the patients performance and tailored support.
In comparison, the underwater treadmill provides a more controlled environment that can be tailored to the individual needs of a patient thought the adjustment of variables such as water depth. The depth of the water enables the distribution of the body weight carried by the dog, with deeper waters ultimately reducing weight bearing (Levine et al. , 2002). In addition to this, the water depth can be used to alter the range of motion of a joint which can be used to reduce pain by reducing extension or to increase range of motion by increasing extension.
Evidence Base
It is widely accepted that only those treatments supported by a body of clinical and scientific evidence to meet the required standards to be integrated into conventional veterinary medicine. Contrary to this, Robinson (2016) detailed how one of the key components when evaluating a treatment, critical analysis, is often overlooked, leading to the acceptance of and integration into practice of treatments that may or may not be effective.
An overall lack of high quality clinical evidence-based scientific research continues to affect the acceptance and practice of both acupuncture and hydrotherapy.
Acupuncture
A growing body of scientific evidence-based research consisting of randomised controlled trials and meta-analysis supports the clinical efficacy of acupuncture in pain management.
Electroacupuncture, in which an electrical current is applied to the acupuncture points in order to enhance the stimulation to the needles, is a commonly used acupuncture-related technique used to enhance the outcome and prolong the benefits of the treatment, an effect confirmed following imaging studies. Much research has evaluated the use of electroacupuncture to treat performance horses suffering from chronic back pain (Xie et al. , 2005), that is resistant to conventional drug therapy in addition to small animal medicine as a complementary treatment to conventional veterinary medicine.
The findings of this research provided scientific evidence that an analgesic effect can be seen after just three sessions of electroacupuncture in horses, with the analgesic effect lasting for a minimum of two weeks (Xie et al. , 2005). However, the true effectiveness of acupuncture both short and long terms remains unknown, with little veterinary research having examined the effectiveness of acupuncture when used alongside manual therapies, with the available evidence from human medicine.
Of positive news, preliminary research in veterinary medicine has shown acupuncture to provide short-term benefits in pain management when used in combination with manual therapy, but the manual therapy routine was not specified (Lane and Hill, 2016). Unfortunately, due to the combination of treatments that were administered being unknown it is not possible to determine the cause of the improvement and thus this study provides no conclusive evidence for the individual benefit of using acupuncture. However, when acupuncture was compared with the use of the nonsteroidal anti-inflammatory drug phenylbutazone, it was found that this alone does not effectively relieve pain.
Following on from this, research by Hayashi et al. (2007) found 88. 5% of dogs to respond positively to a treatment plan consisting of acupuncture and conventional medications, significantly higher than the 58. 3% reported for those receiving only the latter. Joaquim et al. (2010); Hayash et al. (2007); and Jaeger et al. (2007) found similar results however contrary to this, in the comparison of acupuncture against conventional medication, only very low-quality evidence shows that acupuncture is more effective in relieving pain in both the short and long term (Zhang et al. , 2019).
Research investigating the efficacy of acupuncture for canine elbow and hip osteoarthritis reported no significant improvement in pain scores with Teixeira et al. (2016) reporting that in dogs with hip dysplasia, acupuncture was not significantly different from groups receiving a placebo or the nonsteroidal anti-inflammatory drug carprofen. Of great significance, the research of Kapatkin et al. (2006) found that despite this being a blind study, owners were able to accurately determine if their dog had received treatment, observing an overall improvement in their dog's behavior, providing a valid and reliable method in which the efficacy of acupuncture can be assessed.
The challenge with integrating acupuncture into veterinary medicine is the superficial understanding of the processes within the brain that affect pain perception in pain management. Although there is growing evidence for the analgesic effects of acupuncture, current understanding of central regulatory events of analgesia remains limited and it must be considered that the limbic system is likely stimulated by nonspecific acupuncture points (Fry et al. , 2014). Treatment points are less specific to the central nervous system, and these effects should be considered complementary to conventional treatments.
Hydrotherapy
A poor understanding of the mechanisms of canine movement through water and subsequent pain relief is a theme consistent throughout the available literature. Upon reviewing the human evidence, Mendez-Angulo et al. (2013) highlighted the benefits of hydrotherapy performed using an underwater treadmill in the management of osteoarthritis in reducing chronic pain and increasing joint mobility. Similar effects were reported by Dias et al. , (2017) who found hydrotherapy to reduce pain in older women with osteoarthritis over a six week period. This has also been demonstrated in the canine based research of Parkinson et al. (2018), Preston and Wills (2018) and Barnicoat and Wills (2016) despite these studies not directly assessing pain, through improvements in locomotory functioning.
A randomised controlled trial conducted by Hinman et al. (2007) on human subjects reported a significant improvement in pain when compared to those who received no treatment, but it remains to be known if this was due to the therapy itself or a placebo response. Similar findings have been reported in the veterinary literature. The more recent research of Hinman et al. (2014) contradicts previous findings, concluding that neither laser or needle acupuncture significantly improves pain over a time span of twelve weeks or one year in human subjects.
The research of Hinman et al. (2014) partially supports that of Vickers et al. (2012) who though a systematic review and individual patient data meta-analysis on acupuncture efficacy for osteoarthritis, found moderate improvements in pain with needle acupuncture compared with no acupuncture and much smaller but statistically significant improvements compared with sham acupuncture, suggesting that factors in addition to the specific effects of needling are important contributors to the therapeutic effects of acupuncture.
In human medicine, randomised control trials have taken place to compare aquatic therapy with land-based therapy. Silva et al. (2008) concluded that whilst both land and water based therapies provide pain relief, hydrotherapy was found to produce higher levels of pain relief. Conversely, in the same year, Mcveigh et al. (2008), found no significant difference in the analgesic effect of aquatic therapy compared with land-based therapy. However, Denning et al. (2012) confirmed that researchers tend to report no difference in pain levels during water exercise compared with land exercise despite there being a significant decrease in pain using both mediums. Tangjitjaroen et al. (2009) therefore state that such research should therefore be interpreted with caution with Hutchinson et al. (2012) adding that no conclusions can be drawn about its effectiveness over other treatment modalities as the evidence is conflicting.
It has been hypothesised that even in the presence of chronic pain, hydrotherapy enhances the early dynamic muscular strengthening and locomotory mobility. It may therefore be that the reduction in pain associated with increased locomotor mobility, is in fact due to an increased pain tolerance, however further research is needed to validate this claim.
Physiological Effects
The safe use of any treatment is reliant on it being performed by an experienced, well-trained practitioner, with governing and professional bodies in place to regulate the practice of such treatments for example the Association of British Veterinary Acupuncturist, Canine Hydrotherapy Association and the National Association of Registered Canine Hydrotherapists.
Under the Veterinary Surgeons Act 1966 and the later Veterinary Surgeons Exemptions Order 2015, acupuncture may only be administered by appropriately qualified veterinary surgeons. With the increased demand for veterinary acupuncture, increasing numbers of veterinarians are pursuing advanced training to meet this demand. However, accurate needle placement remains challenging, with individual practitioners relying on varying methods of point identification, often compounded by the transpositional nature of points for companion animals.
The results of research by Yang et al. (2017) indicate that veterinary patients receiving acupuncture treatment from veterinarians with different levels of training may subsequently experience varying effects, with veterinary surgeons who were certified in veterinary acupuncture and possess more clinical experience placeneedles with greater accuracy, although further studies are warranted on more specific acupoint description as well as the clinical implications of needle placement accuracy.
In summary, acupuncture is said to pose minimal risks and to be well-tolerated with White (2004) in a review of 12 prospective human studies, including over a million treatments, the risk of a serious estimated the risk of a serious adverse effect was 0. 05 times per 10,000 treatments, a figure below that of many common medical treatments. Although there are very few reports of adverse reactions to acupuncture in animals, this does not mean that they have not occurred or that they will not occur now that more veterinarians are carrying out this form of treatment.
Developments in neuroscience and pain management have contributed to advances in understanding of the physiological responses to complementary and alternative medicines. Acupuncture has been shown to elicit similar effects in humans and other mammals, suggesting that they bring about fundamental physiological changes, making this treatment more than just a placebo.
Both human and animal based literature have documented that acupuncture relieves pain with minimal cardiorespiratory effects. These effects have been found to be comparable to those of commonly used analgesics. In relation to hydrotherapy, few studies have reported the evidence-based effects of hydrotherapy on various systems, yet Mooventhan and Nivethitha (2014) concluded that the hydrotherapy has a scientific evidence based effect on various systems of the body, with Egan and Fitzpatrick (2017) stating that in humans, underwater exercise has been shown to generate less cardiovascular and respiratory demand than equivalent land‐based activities. However, minimal research has evaluated the physiological and biomechanical parameters of healthy and ill or injured dogs during aquatic exercise, that is needed to confirm the true efficacy of this treatment.
Studies using an underwater treadmill have demonstrated that water depth, temperature and speed have a significant effect on physiological responses in humans but it remains unknown what affect of speed and water depth have on these parameters in equines and canines.
Suitability in Pain Management
Researchers have come to different conclusions when defining a clinically minimal pain improvement and have often reported percentage improvement and not an absolute effect size. However, the apparent analgesic effect of acupuncture seems to be below a clinically relevant pain improvement with there being no evidence to suggest that acupuncture is more effective than other therapeutic modality. In fact, it appears that hydrotherapy is more effective in reducing pain than electrotherapy, with repeated hydrotherapy sessions shown to create superior level of analgesia. Furthermore, it is possible that patients receiving aquatic-based exercises could tolerate more intense exercises, which could result in greater improvements than have currently been shown.
Conclusion
Despite a lack of high quality veterinary studies evaluating their efficacy, conclusions drawn from the available literature suggest that both acupuncture and hydrotherapy can be safely and effectively used alongside conventional veterinary medicine in the management of pain. However, with the analgesic effect of acupuncture appearing to be insignificant and the conclusion being that there is insufficient evidence to either accept or reject acupuncture as a valid treatment modality and there being no evidence to suggest that acupuncture is more effective than other active therapies, it is fair to suggest that hydrotherapy is the more suitable treatment option for pain management.
