December 2023 21 Land-based therapeutic exercises comprise simple exercises such as walking, with a gradual build-up of the duration of each walk depending on the dogs’ comfort (Greene et al. 2013). Using command-driven exercises such as sit, lying down and bowing, are strengthening exercises, and can be carried out at home by owners (Drum et al. 2021). Exercising using exercise equipment, such as balance boards and exercise balls can be beneficial to build balance and strength, ideally by a trained canine physiotherapist (Goldberg 2022). A thorough review of the use of strengthening exercises has been recently published (Drum et al. 2021). Published studies investigating the efficacy of land-based therapeutic exercise for the management of canine OA are limited. Previous studies have examined how different exercises affect the gait of dogs with elbow and hip OA, using kinematic gait analysis, revealing that walking up an incline, down an incline and over low obstacles all alter joint kinematics not just in the OA-affected joint but in multiple joints compared to non-OA Dogs (Bockstahler et al. 2011, Bockstahler et al. 2012). In a clinical setting, Mlacnik et al. (2006) found a significant improvement in lameness of dogs with OA following a weight loss programme with either home-based physical therapy or an intensive physical therapy programme (including TENS) compared to baseline, with improvements seen more rapidly in the intensive physical therapy group. Further clinical trials are required to improve evidence for physiotherapy exercise protocols in canine OA. Hydrotherapy Hydrotherapy is a form of physiotherapy that takes place within water, either with the use of a pool, an underwater treadmill, or (less commonly in the veterinary field) with a whirlpool or hot-tub (Cartlidge 2015). Hydrotherapy is commonly used as a complementary therapy in canine patients with OA with a large number of hydrotherapy centres across the UK (Waining et al. 2011). Exercising in water reduces the degree of weight bearing by limiting the pull of gravity due to the effect of buoyancy (Levine et al. 2010). It has been shown that there is a reduction in vertical ground reaction forces exerted by dogs’ limbs when they are immersed in water, with further decreases in these forces as the water depth increases (Levine et al. 2010, Barnicoat & Wills 2016). By reducing ground reaction forces, it is proposed that hydrotherapy can improve exercise tolerance, by reducing the impact of exercise on dogs with OA-affected limbs (Levine et al. 2010, de Oliveira Reusing et al. 2021). Another potentially therapeutic effect of exercising in water is caused by the effect of hydrostatic pressure, which is the compressive pressure exerted on an object by a body of fluid when immersed in that fluid. Hydrostatic pressure may lead to an improvement in circulation, aiding in the resolution of oedema, lymphoedema, soft tissue and joint swelling, and reducing pain and stiffness in joints (Kamiokaet al. 2010, Gibson & Shields 2015). There is also an increase in resistance when exercising in water due to drag forces, which could lead to increased muscle mass and strength in OA patients (Miyoshi et al. 2004, Barnicoat & Wills 2016). Improved exercise tolerance with hydrotherapy can also help with weight reduction programmes (Chauvet et al. 2011). Weight reduction improved clinical outcomes in OA dogs (see section on weight management above) (Marshall et al. 2010). Water temperature of the hydrotherapy pool or treadmill could also impact treatment efficacy. A temperature of between 28°C and 30°C has been recommended for canine hydrotherapy (Prankel 2008, Lindley & Watson 2010). Alternating between warm and cold water, a process known as contrast hydrotherapy, has been investigated in humans finding potential benefits versus either warm or cold water alone (Abd Elfatah et al. 2019, Fokmare Jr & Phansopkar 2022), but no studies have been published in dogs. Altogether, these physical aspects of aquatic exercise are hypothesised to lead to improved exercise tolerance, improved balance and co-ordination during exercise, improved joint mobility and reduced joint stiffness improved muscle strength, reduced swelling around affected joints and an overall reduction in OA-related pain (Bartels et al. 2016). A number of studies have investigated how hydrotherapy, either by underwater treadmill or swimming, affected the gait of healthy dogs (Levine et al. 2010, Barnicoat & Wills 2016, Bliss et al. 2022) and those with orthopaedic disorders such as elbow dysplasia (Preston & Wills 2018) and postoperative rehabilitation after cranial cruciate ligament rupture (CCLR) surgery (Marsolais et al. 2003). However, there are limited studies investigating the clinical outcomes such as reduction in lameness and pain in dogs with OA. During and after an eight-week programme of hydrotherapy with outdoor pool swimming in a group of 22 dogs with hip OA, subjective clinical assessment scores including pain, lameness and joint mobility significantly improved in the OA dogs (Nganvongpanit et al. 2014). Interestingly, serum biomarkers of OA also significantly changed in the OA-affected dogs in this study, with an increase in serum hyaluronan and a decrease in serum chondroitin sulphate epitope WF6 suggesting a reduction in cartilage breakdown in these dogs (Nganvongpanit et al. 2014). Serum hyaluronan also increased in healthy dogs that underwent swimming, but not in healthy dogs that did not swim. One major limitation to this study was the lack of a control group. A recent study found reductions in pain severity (as measured by the CBPI) and an increase in thigh circumference in dogs with hip OA after twice weekly hydrotherapy sessions in an underwater treadmill either as a sole treatment or with other physical therapy modalities versus no physical therapy (de Oliveira Reusing et al. 2021). Despite hydrotherapy being more readily available and widely used as a complementary therapy in canine OA (Waining et al. 2011), there is currently a very limited number of clinical studies using this therapy in the literature (Nganvongpanit et al. 2014, Preston & Wills 2018, de Oliveira Reusing et al. 2021). This is not to say that hydrotherapy is not an effective therapy in OA, as there is evidence in the literature supporting its use in human OA (Bartels et al. 2016), and many anecdotal reports of its benefits in canine OA (Prankel 2008), but the lack of studies into its use in canine OA highlights a gap in the evidence base to gain a better understanding of its effectiveness in reducing pain and clinical signs in dogs with OA. OTHER THERAPEUTIC MODALITIES Other therapeutic modalities implemented in physiotherapeutic regimes for canine OA include photobiomodulation therapy (laser therapy), magnetic field therapy, electrotherapy (including transcutaneous electrical nerve stimulation), extracorporeal shockwave therapy and therapeutic ultrasound (Mueller et al. 2007, Gaynor et al. 2018, Barale et al. 2022, Boström et al. 2022). These therapies are based upon the application of different energies to an affected area. Due to the limited scope of this review, an overview of these techniques and their evidence is given here. Details of clinical trials using these modalities aregiven in Table 4. Leading Article
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