A clinically reasoned approach toward pain management should be an overriding priority when managing degenerative joint disease. A clinician should advocate the employment of interventions to widen the treatment plan, addressing the joint dysfunction and compensatory impact on the rest of the musculoskeletal system. Consequences of adapted posture and movement must also be addressed to achieve optimal outcomes and improve quality of life long term. It is well known that simply reducing pain will not automatically promote a return to previous function, as a result of the chronic tissue remodelling, gait adaptation and subsequent neuromuscular adaptations that occur (Fox, 2016; Bockstahler et al, 2019). A staged approach, incorporating rehabilitation to address the consequences of chronic inflammatory somatic and neuropathic/neurogenic pain on the whole body, is required to promote maximal function (Fox, 2016). An approach to disease and dysfunction management that attends to long-term neuromuscular adaptations will inevitably have a positive influence on pain through physical, cognitive and emotional means.
To incorporate a rehabilitative approach, a clinician requires a summary understanding of the resultant pathophysiological changes of degenerative joint disease.
Osteoarthritis is a combination of:
- Loss of articular cartilage
- Synovial membrane inflammation
- Hyperplasia and fibrosis of the joint capsule
- Subchondral bone sclerosis
- Formation of periarticular osteophytes.
Local inflammation leads to peripheral sensitisation and subsequent central sensitisation (Fox, 2016; Knazovicky et al, 2016). Correspondingly, the pain experienced is no longer contained to the joint during weight bearing, resulting in a reluctance to exercise, soft tissue degeneration, fibrosis and atrophy locally, then with increasing chronicity and distance to the original pathology (Fox, 2010, 2016; Cachon et al, 2018). This pathology is likely to promote weight gain as an animal's reduced activity is rarely accounted for in the caregiver's dietary calculations (Wakshlag and Loft us, 2014) (Figure 1). Increased weight carriage results in greater load bearing, affecting the biomechanical forces distributed through compromised articulating surfaces (Marshall et al, 2010). The consequences of altered load distribution and increased biomechanical forces are increased dysfunction, pain and reduction in mobility, which has been proven to have a detrimental impact on emotional health (Wright, 2010; Mills et al, 2020) (Figure 2). There is extensive evidence for adaptation, away from normal posture and gait, resulting in associated refractory myofascial discomfort and compensatory dysfunction (Wright, 2010). This negative cycle of degenerative changes, involving the whole body, is well established to varying degrees by the time the disease is identified (Cachon et al, 2018).
It is well documented that significant pain and locomotor dysfunction is already present when dogs are commonly presented (Cachon et al, 2018). More than 50% of cases of canine arthritis are diagnosed when the animal is over 8 years old, despite the dominant aetiology being developmental joint disease (Mele, 2007). The delayed presentation and recognition of pathology is thought to be a consequence of the lack of public awareness and poor owner education. Limited understanding of early indicators of pain and inhibited treatment plans, caused by numerous psychosocial factors of stakeholders, lead to delayed action and disease progression (Belshaw et al, 2016; Belshaw, 2017).
Reducing pain alone will not ‘rewire’ the myriad modifications the body has made (Figure 3). Relying on a dog to accurately redistribute weight bearing and performance-related forces with respect to tissue remodelling requirements and timescales is wishful thinking. In fact, simply reducing the discomfort may lead to progression of the osteoarthritis syndrome, with premature introduction of taxing activities having a negative impact on a chronic self-perpetuating degenerative disease process and its associated compensatory pathology (Berenbaum, 2019).
Multimodal management
Incorporating rehabilitation into a multimodal management plan requires a clear understanding of the dog's overall physical health and a comprehensive neuromusculoskeletal diagnosis.
A multimodal approach is universally agreed to be the best for optimal management of this chronically painful and progressive disease (Fox, 2016). The dog's pain state should direct the initial treatment strategy, which may require further investigations. However, if an animal is centrally sensitised, a pharmaceutical approach should be prioritised and adding physical modalities should be delayed until the animal is better able to tolerate this. It is unethical and unproductive to implement any intervention that exacerbates pain, which may conflict with measures taken to obtain a definitive diagnosis (Hellyer et al, 2007). In addition to adding analgesia, an often overlooked intervention that should be addressed at this stage is environmental modification to ensure no further exacerbation of the disease through slips, trips and falls on slick floors and stairs.
When handling is comfortably tolerated, a full pain assessment, as well as neurological and orthopaedic examinations, can be performed and a suitable plan constructed. Incorporating rehabilitation into the multimodal approach requires an understanding of what tissues are affected, to what degree and where. Applying physical modalities without targets, intentions and timelines will produce less than optimal results and could adversely affect owner compliance or inflict harm (Bockstahler et al, 2019).
The author advises that a generous amount of time be allocated for detailed history taking, including questions on lifestyle and home environment, as well as clinical observations of gaits and transitions. Examination should be performed in a quiet spacious location and start with good visual assessment looking for asymmetry in the muscle mass and tone, and observing for offloading of limbs when standing and sitting. No clinician should be shy of a crib sheet when performing a clinical exam, as there is nothing more infuriating than finding that a key assessment has been missed.
Tools commonly used when collecting data include a Gulick tape to measure muscle mass, a goniometer to measure joint angles and a reflex hammer to elicit local reflexes. Stance and gait analysers can also be used as additional tools (Brown et al, 2013; Carr and Dycus, 2016). It is important to note that gentle handling is imperative during diagnostic examination. Tools such as reflex hammers can cause pain and standard reflex hammers may be overwhelming when used on smaller breeds and clinicians should be cognisant of not inflicting further pain on the animal.
Early detection of osteoarthritis often continues to elude clinicians, leading to development of compensatory pathology caused by adapted posture and movement patterns. Taking time to appreciate the primary disease and its secondary pathologies is important for strategising therapeutic goals, managing expectations and improving owner comprehension and motivation. Box 1 details an example explanation to an owner of a dog with osteoarthritis.
Box 1.The author has found this approach engages the owner in the treatment plan and motivates action, especially regarding weight loss and lifestyle adaptations‘Your dog's original condition was developmental hip dysplasia, which developed partly as a result of genetic influence. This progressed to clinical hip osteoarthritis, which caused pain and dysfunction of the hips. Initially your dog adapted by redistributing their weight into the forequarters. However, over time this has led to increased discomfort emanating from the hips caused by loss of surrounding soft tissue support through lack of use. It has also led to overloading of the structures of the forelimbs, resulting in muscle and tendon discomfort and reduced function. Together these have resulted in your dog having an increased pain state, causing unwillingness to engage or exercise, which will have contributed to their weight gain which has exacerbated both the original and subsequent pathologies.’
A necessary consideration when creating a multimodal rehabilitation plan is the acute or chronic, progressive nature of osteoarthritis (Fox, 2016). Acute flares are a regular yet poorly defined feature of osteoarthritis in humans, and are prevalent in canine osteoarthritis management (Egger et al, 2014; Parry et al, 2018, 2019; Thomas and Neogi, 2020). Identifying acute flares relies on the owner's observation of signs of increased pain, plus a thorough examination which localises the pain to a joint and not to a secondary soft tissue focus. In the author's experience, acute deteriorations are often caused by compensation, lifestyle and activity-associated exacerbation. This is something clinicians ought to be vigilant for (Figure 4).
Translating a human approach and creating a three-layer plan for management can be a useful addition when formulating a multimodal approach. The baseline plan has the intention of long-term disease modification. The second layer is aimed at managing acute flares and deteriorations. The tertiary advisory layer is aimed at identifying the acute flare ‘triggers’ and crafting a plan of avoidance (Thomas and Neogi, 2020). This approach is excellent at encouraging necessary lifestyle modification and is a feature in the National Institute for Health and Care Excellence guidelines for human healthcare. It is worth noting that certain baseline interventions continue through an acute flare, whereas some will be interrupted, such as a therapeutic exercise plan or exercise quotient.
Physical modalities
Physical modalities used in rehabilitation offer differing attributes that decrease pain and promote tissue healing and regeneration. Incorporating the appropriate modality is imperative, especially as osteoarthritis describes a diverse array of clinical presentations. There is no one size fits all approach.
Physical modalities aim to augment and expedite the body's own regenerative and remodelling potential. A simplified review of the impact of osteoarthritis on tissues will guide the clinician to choose which therapy may be appropriate and when.
The joint
The structures of an osteoarthritic joint degenerate as a result of fluctuating local inflammation and lack of loading. The well innervated sclerosed subchondral bone, inflamed synovium and fibrosed joint capsule are sources of pain. The combination of chronic changes to the joint capsule, osteophyte deposition and pain limits joint range of motion.
The surrounding soft tissue
The supportive muscles, tendons and ligaments undergo disuse atrophy, with associated fascial and neuromuscular changes leading to paresis and proprioceptive deficits.
The compensatory changes and adapted posture
To maintain mobility, weight carriage is redistributed to other regions resulting in an abnormal posture, movement disorders and pain, all of which perpetuate tissue adaptation and compensation (Fox, 2016; Bockstahler et al, 2019). A common presentation in veterinary practice is a dog that has reached a crisis point and is no longer able to maintain load redistribution, postural adjustments and locomotive compensations to perform activities of daily living.
A rehabilitative mindset
The aim of rehabilitation is to reduce the severity of the clinical signs, potentially decrease reliance on medications to maintain an appropriate level of hypoalgesia, and improve or maintain effective functional independent movement, tailored to that dog's lifestyle, ensuring an optimal quality of life (Fox, 2010).
Structuring your observations and asking yourself pertinent questions to ensure an open-minded approach which will ensure other potential comorbidities are not overlooked (Figure 5).
Consideration of the biopsychosocial healthcare model is pertinent to a rehabilitative mindset. Data regarding adherence to treatment plans are lacking in veterinary care, although literature from human healthcare indicates 50% of physiotherapy plans are not adhered to (Peek et al, 2016). This understanding should encourage clinicians to be cognisant of what owners can sustain physically, emotionally, financially and time wise. Gaining this information and understanding will help guide interventions and improve caregiver compliance (Jack et al, 2010; Peek et al, 2016). For example, introducing a list of ten therapeutic exercises to be done three times daily is too optimistic for a working professional, as is six photobiomodulation sessions over 3 weeks for an owner on a compromised budget. Therefore, it could be argued that advocating an intervention that you know will have poor compliance is unfair to the modality, the owner and the animal.
Interventions readily available to a first opinion practitioner
Exercise modification
Simple lead walking, in a controlled manner with appropriate restraints, is an underappreciated addition to a therapeutic exercise regimen (Fox, 2016). This simple symmetrical gait encourages the use of all limbs and, through slowing the walk and the stance time, duration of loading can be increased (Bockstahler et al, 2019). Incremental and appropriate loading of a joint will contribute to joint health, as synovial fluid production and cartilage health is dependent on weight bearing compression. Weight bearing maintains soft tissue, contributing to overall stability, which is essential to slowing the progression of osteoarthritis (Brandt et al, 2010).
Once an appropriate functional gait pattern has been established, increasing the pace of the walk will improve cardiorespiratory fitness and oxygenated blood supply. It will challenge balance and proprioception, as well as increasing forces which promote muscular strength and stamina (Bockstahler et al, 2019).
Adding inclines and declines promotes increased range of motion, eccentric and concentric muscle actions, and redistributes the propulsive and braking forces (Holler et al, 2010). Changing the terrain, such as long grass or uneven surfaces, can also increase joint range of motion and muscular strength, as well as challenging proprioception and balance (Bockstahler et al, 2019). Changing the pace to a trot dramatically increases the loads placed on the forelimbs from 65% to 120%, and hindlimbs from 40% to 75%, promoting strength, power and endurance (Bockstahler et al, 2019).
Conversely, during severe flare ups of osteoarthritis, many dogs need to be restricted to a pace no faster than walking to reduce loading and to allow the inflammation of joints and their surrounding tissues to settle down. Providing specific recommendations regarding appropriate exercise can significantly contribute to case management and can prevent deterioration. In the author's experience, over-exercising and the consequent fatigue and exacerbation of pain and dysfunction is a primary cause for crisis presentations.
Environmental modification
This simple intervention is commonly overlooked as there is a lack of data examining the environment in relation to its influence on disease in adult dogs (Roddy and Doherty, 2006; Bortoluzzi et al, 2018; Bowden et al, 2021). There is emerging evidence suggesting a correlation between the incidence of developmental disease and activity, husbandry and the environment (Marjan et al, 2005; Ginja et al, 2010).
Osteoarthritis disables the sufferer, leaving them prone to slips, trips and falls. Avoiding exposing the dog to these risks is a simple, powerful and very cost-effective intervention. Common suggestions involve providing non-slip flooring in the form of rugs and runners, reducing access to the stairs, modifying difficult access points, or providing easier routes onto the sofa and beds. This list is far from exhaustive. Please refer to #itsmyhometoo too from Canine Arthritis Management for further suggestions (https://caninearthritis.co.uk/itsmyhometoo/).
Lifestyle adaption
Another easily implementable intervention, again lacking in descriptive literature but linked to acute flare-ups in other species (van Weeren and Back, 2016; Thomas and Neogi, 2020), is modifying a dog's lifestyle. Unwitting owners will allow often allow their dogs to do ‘what makes them happy’, but this is often unsuitable for their condition and capabilities. Advising on appropriate activities to do, independent of exercise and the home environment, is time well spent. Examples of inappropriate activities include sprint and fetch games or encouraging obsessive routines like chasing cats and squirrels. Please refer to the Interactive Lifestyle Tool by Canine Arthritis Management for further suggestions (https://caninearthritis.co.uk/lifestyle-tool/).
Weight control
Achieving optimum body weight should be aspiration in all cases of osteoarthritis. Among many studies investigating the effect of weight loss on osteoarthritis pain, a reduction in body weight of only 6.1% has been shown to relieve lameness, owing to a reduction in biomechanical and biochemical influence (Marshall et al, 2010). Supporting the owner with a calculated nutritional plan and appropriate exercise plan is an imperative intervention, as well as correcting any misunderstanding that weight loss is reliant solely on exercise. Exercise certainly contributes to maintenance of lean body mass and cardiovascular fitness, but successful weight loss primarily requires dietary modification (Mlacnik et al, 2006; Vitger et al, 2016). A sudden increase in exercise quotient with the intention of ‘burning calories’ is likely to be detrimental to the compromised joint and surrounding soft tissues (Brady et al, 2013).
Thermo and cryotherapy
Cryotherapy is suitable for peripheral joints and tissues to a depth of approximately 2 cm (Bocobo et al, 1991; Millard et al, 2013). A variety of low-cost topical cold compresses can be used to reduce blood flow through vasoconstriction, subsequently reducing inflammation, swelling, pain and muscle spasms. Reducing the temperature of the tissue via conduction will slow unwanted catabolic tissue metabolism, as well as nociceptive nerve conduction. It is generally employed post-surgery and after exercise, applied to compromised joints for 10–20 minutes up to 3–6 times daily (Bockstahler et al, 2019).
Simple radiant (heat lamp) or conductive (heat sack) thermotherapy is suitable for peripheral joints and tissues to a depth of approximately 2 cm (Hanks et al, 2015). It increases blood flow, tissue metabolism and improves tissue extensibility, subsequently promoting tissue healing, reduction of muscle spasms, improved joint range of motion and decreased pain (Bockstahler et al, 2019).
Care must be taken to not cause heat or cold burns, especially in dogs with compromised somatic sensation.
Manual therapies
Manual therapies can range from simple effleurage and passive range of motion, carried out by the owner with appropriate instruction and reassessment, through to grade 4 joint mobilisations that require competency and experience. Differing techniques have different intentions. Some focus on tissues that have lost their normal pliability and are tight and painful because of the adapted movement patterns and load bearing. Others focus on stimulating hypotonic atrophied tissues with the intention of revitalising them ready for action (Bockstahler et al, 2019).
Massage increases blood flow and assists venous return and lymphatic drainage, stimulates the release of endorphins as well as influencing muscle tone and stimulating neural feedback (Bockstahler et al, 2019). Myofascial techniques aim to release tension, manage myofascial trigger points and encourage normal tissue movement (Broadhurst, 2019). Range of motion exercises can be passive or active and maintain joint mobility joint health and reduce pain (Bockstahler et al, 2019). Stretching focuses on maintaining and improving surrounding soft tissue flexibility and aims to prevent muscle shortening and contractures, although its benefit is debated (Harvey et al, 2017). Joint mobilising is a graded active intervention to improve joint range of motion and reduce pain and swelling (Saunders et al, 2005).
Therapeutic exercises
As previously explained, osteoarthritis leads to chronic weight shifting and adaption, which in turn leads to imbalance and dysfunction. By targeting exercises to specific regions, strength, flexibility, balance, proprioception and stamina can be improved, resulting in long-term physical fitness and inherent capability to deal with activities of daily living (McCauley and Van Dyke, 2018; Bockstahler et al, 2019).
A thorough assessment should aim to identify which areas are lacking in stability and where is compensating, so appropriate exercises can be chosen to either build or relax the tissues. The chosen exercise regimen should then be regularly remodelled to match the dog's changing physical status.
Exercises range from simple to challenging and feature variations of weight shifting, balance, proprioception challenge and strengthening. Dependent on the dog's progress, exercises can be added concentrating on power, agility and endurance to reestablish an acceptable level of physical activity.
Acupuncture
Dry needling and acupuncture can only be performed by a veterinary surgeon, or under their direct guidance. It is used by many experienced chronic pain practitioners for both local myofascial and systemic effects, potentially explained by local tissue stimulation, endogenous opioid release and the pain gate theory (Lindley, 2006).
Transcutaneous electrical nerve stimulation
Stimulating the skin with milliampere electric currents, either local to the pain inducing pathology or local to the spine according to the relevant myotome where the pathology resides, works to decrease pain transmission via the pain gate theory and through the release of endorphins. The tolerable electrical current stimulates fast transmission A-β fibres which inhibit transmission via nociceptive A-δ and C-fibres (Bockstahler et al, 2019).
This modality is affordable and effective for both acute and chronic pain and is routinely used in human healthcare (Johnson et al, 2015; Gibson et al, 2019). It is a safe intervention that can be carried out by the owner who would need to apply it regularly, dependent on the pain state, for best effect.
Neuromuscular electrical nerve stimulation
Directly stimulating muscle contraction through electrical stimulation can stem off disuse atrophy as well as augment functional recovery of lost muscle mass commonly seen in dogs that have weight shifted for a significant time (Bockstahler et al, 2019). Voluntary skeletal muscle contraction is superior to electrical stimulation as it preferentially maintains the fatigue resistant postural muscles, whereas the latter tends to target the fast twitch quick-to-fatigue muscles designed for activity (Hainaut and Duchateau, 1992). In addition, the caregiver must be commited to applying the electrodes to the muscle once daily for 20–30 minutes to see the benefit.
Conclusions
The above list only features interventions that are readily available to practices looking to expand their chronic pain service to include a rehabilitative ethos. Pulsed electromagnetic field therapy, hydrotherapy, laser therapy, ultrasound, extracorporeal shock wave therapy and intra-articular therapies are included in a rehabilitative approach and are currently accruing data to support their value, but as they require significant outlay on equipment they have been excluded from this article.
Rehabilitation is a rapidly expanding field complementing an already well-established veterinary physiotherapy discipline. Introducing a rehabilitative ethos into a multimodal osteoarthritis management plan counters the associated physical consequences of this chronic disease, that a pharmaceutical approach alone cannot.
KEY POINTS
- The pain associated with osteoarthritis is complex and successful management requires a multimodal approach, inclusive of rehabilitation.
- Achieving hypoalgesia through pharmaceutical and non-pharmaceutical means is paramount for achieving maximum health related quality of life and longevity.
- An appreciation of the global impact of osteoarthritis on the neuromusculoskeletal system is required when formulating a multimodal management strategy.
- Employing a combined rehabilitative approach requires an informed and engaged client, who is willing and able to invest time and potentially finances in regular intervention, both independently and with qualified guidance.