Vetnuus | Desember 2023 24 « BACK TO CONTENTS QLA Health-related quality of life scale for dogs with signs of pain secondary to cancer, HCPI Helsinki Chronic Pain Index, VAS Visual analogue scale, HD Hip dysplasia, CMI Clinical metrology instrument, CBPI Canine brief pain index, GRF Ground reaction forces, AC Accelerometery, SOS Subjective orthopaedic scoring, CSOM Client-specific outcome measures, PVF Peak vertical force, PI Peak impulse, TENS Transcutaneous electrical nerve stimulation †Published abstract Photobiomodulation therapy (laser therapy) Photobiomodulation therapy (PBMT) has been increasing in popularity in recent years as a therapy for canine OA. The term PBMT encompasses an array of light and laser therapies, and is defined as a “A form of light therapy that utilizes non-ionizing forms of light sources, including lasers, LEDs, and broadband light, in the visible and infrared spectrum” (Anders et al. 2015). The mechanisms behind PBMT and its effect on OA are still being investigated in vitro and in vivo (Oliveira et al. 2021). In laboratory studies, the enzyme cytochrome c oxidase in mitochondria has been found to be a photo-acceptor which is activated by PBMT (Karu et al. 2005) leading to an increased production of molecules involved in cell signalling pathways related to cell proliferation, protein synthesis and anti-inflammatory effects (Karu 2008). In the human field, the evidence behind the use of PBMT in the treatment of OA is mixed, and a lack of consistency between study protocols and methods makes it difficult to draw firm conclusions (Bridges et al. 2020). Recent systematic reviews of published randomised controlled investigating the effect of PBMT on pain and disability in humans with OA concluded that there was some evidence that PBMT provided significant improvements in pain, function and QOL in patients with knee OA and in aged patients with OA, although further research was advised (Stausholm et al. 2019, Bridges et al. 2020). To date, four studies have investigated the efficacy of PBMT in dogs with OA (Table 4). These include three prospective studies (Looney et al. 2018, de Oliveira Reusing et al. 2021, Barale et al. 2022), and one retrospective study (Barale et al. 2020). Looney et al. (2018) investigated the effect of a 6-week Course of low-level laser therapy (LLLT) in 20 dogs with elbow OA, compared to sham light therapy in a multicentre, randomised, blinded, controlled trial. An improvement in subjective lameness score as well as the Helsinki Chronic Pain Index CMI was found in the treated group (Looney et al. 2018). A significant increase in the daily step count and number of daily activities recorded by accelerometery was found after a six-week course of LLLT in 23 dogs with either hip or stifle OA (Barale et al. 2022). Before this publication, the same investigators published the results of a retrospective study on 17 dogs describing the reduction in CBPI and VAS in these dogs with weekly LLLT treatments (Barale et al. 2020). Electromagnetic field therapy Electromagnetic field therapy involves the application of a magnetic field (either low frequency, high frequency or pulsed) to an area to promote a therapeutic benefit. Pulsed electromagnetic field therapy (PEMT) is most commonly used in veterinary medicine (Gaynor et al. 2018). Two randomised controlled trials investigated the efficacy of PEMT in dogs with OA (Pinna et al. 2013, Sullivan et al. 2013). Sullivan et al. (2013) compared treatment with PEMT for 1 hour on 9 consecutive days in 35 dogs with an untreated control group of 24 dogs. The PEMT group had lower CBPI scores at assessment timepoints of 11 and 42 days. Another clinical trial examining the effects of PEMT in 40 OAaffected dogs also found evidence of a clinical improvement similar to a firocoxib-treated control group (Pinna et al. 2013). Extra-corporeal shockwave treatment Extra-corporeal shockwave therapy (ECSWT) involves the application of shockwaves (which are non-linear, high pressure, high-velocity sound waves of short duration) to a treatment site, in order to transmit mechanical energy to the tissues (Durant & Millis 2014, Alvarez 2022). This mechanical energy transmitted by the shockwave acts directly and indirectly on the tissue to generate an anti-inflammatory response, by the production of free radicals, anti-inflammatory cytokines and growth factors within tissues that can reduce inflammation and promote healing (Durant & Millis 2014). The mechanisms behind the analgesic effect of shockwaves are less well understood (McClure et al. 2005, Abed et al. 2007). A few small randomised controlled trials have investigated the efficacy of ECSWT in OA dogs. Souza et al. (2016) found improvements in objective force plate gait analysis in dogs with hip dysplasia for up to 90 days. However, Mueller et al. (2007) found no significant improvements in gait analysis in dogs with hip OA treated with ECSWT. Millis et al. (2011) found significant improvements in objective gait analysis in dogs with elbow OA treated by ECSWT, although the sample size in this trial was small at 15 dogs. Therapeutic ultrasound Therapeutic ultrasound is the application of either continuous or pulsed ultrasound waves, at either low or high frequencies, to tissues to gain a therapeutic effect (Boström et al. 2022). The therapeutic effects may be elicited via both thermal and non-thermal effects. Thermal effects on tissue by the application of ultrasound waves increase blood flow, and non-thermal mechanical energy affects cell membranes, leading to release of growth factors (Tezel & Mitragotri 2003, Tsai et al. 2006). A recent meta-analysis including eight studies found some evidence that pulsed ultrasound therapy led to improvement in function and pain relief compared to placebo in human knee OA (Zeng et al. 2014). In dogs, one study of eight dogs with stifle OA receiving therapeutic ultrasound found improvements in joint mobility and reduced subjective pain scores after 10 daily sessions. However, this study did not include a control group, and gave little information on whether the OA was posttraumatic (e.g. after CCLR), whether it was chronic or acute, and if other medications were given concurrently (Muste et al. 2015). Transcutaneous electrical nerve stimulations Transcutaneous electrical nerve stimulation (TENS) is a form of electrotherapy, where a mild electrical current is applied via a device with patches applied to the skin, to stimulate nerves in the tissue to achieve an analgesic effect (Chen et al. 2016). These effects are believed to be exerted through over-riding nociceptive signals, and by triggering release of endorphins centrally (Han et al. 1991, Radhakrishnan & Sluka 2005). In human OA, there are mixed conclusions as to the effectiveness of TENS. One systematic review and meta-analysis of 18 randomised-controlled trials concluded that TENS reduced pain in knee OA (Chen et al. 2016), whereas another found the evidence was inconclusive (Rutjes et al. 2009). In dogs, no clinical trials have examined the use of TENS alone as a therapy for canine OA. One study examined the use of TENS along with other physical therapies and weight reduction programmes compared to home-based exercise in obese dogs with OA, but conclusions as to whether TENS or weight loss or the other exercises led to an improvement in clinical signs cannot be drawn as all of these modalities were implemented simultaneously in the treated group (Mlacnik et al. 2006). SUMMARY OA is a progressive, degenerative disease which can cause inflammation within the joints and poses a risk to canine health and welfare (Summers Current evidence for non-pharmaceutical, non-surgical treatments of canine osteoarthritis <<< 23
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