Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA
It is helpful to think of joint disease as a metabolic imbalance shifted toward catabolism. Joint disease not only affects joint cartilage and synovium, but also subchondral bone, periarticular muscles and tendons, pain perception, cardiovascular fitness, and, ultimately, the patient as a whole. The painful patient is less active and less interested in play and begins to lose muscle mass and cardiovascular fitness while gaining weight. The normal family activity routines are often upset. Not surprisingly, effective joint health management must be directed at the entire patient, rather than simply at the inflamed joint. Further, joint health must be preserved at the earliest notion that it may be at risk of developing OA. In my opinion, every post-surgical joint patient should be placed in a joint health preservation program.
Pet-owner education is the foundation of effective preservation of joint health because comprehensive joint care requires the pet-owning family’s active involvement and understanding of treatment goals. It is essential that pet owners understand that joint health preservation, like OA management, is an ongoing, lifelong process that is updated and modified based upon response to treatment and development of new therapies, etc.
Attaining and maintaining a lean body conformation through proper nutrition and feeding practices is the cornerstone of effective joint health preservation. Unfortunately, over-feeding is the single hardest habit for pet owners to change. Studies have shown the effectiveness of restricted food intake on weight reduction, delaying the onset of and decreasing the lameness associated with OA and increasing patient lifespan. The challenge is accomplishing the restricted food intake through controlled feeding, especially in multi-pet households or where feeding is a large part of the human-pet bond.
A lifestyle of regular activity that is moderated away from intermittent extremes of exercise and activities to which the pet is not conditioned is essential. This is very difficult for many pet owners, because it, by necessity, impacts their daily schedule. Interestingly, a shift to this desirable lifestyle often benefits the pet owner simultaneously…everyone wins!
Therapeutic exercise and physical rehabilitation under the direction of a certified canine rehabilitation practitioner often contribute to dramatic improvement in comfort, mobility and condition of osteoarthritic dogs. Therapeutic exercise is a key step in converting the osteoarthritic, overweight and sedentary dog to a lean, physically fit dog that is enthusiastic about activity again.
Diets specifically formulated for the dog with OA have a practical place in the comprehensive management of OA. Omega-3 fatty acids, a key component of these diets, appear to decrease joint inflammation, improve lameness and patient activity and reduce reliance upon NSAIDs.
Nutritional supplementation with so-called nutraceuticals containing chondroitin, glucosamine and manganese ascorbate has an apparent role in managing OA and preserving joint health. Combined, they function as building blocks to some of the normal constituents of joint cartilage and they decrease the effect of some of the destructive enzymes present within an osteoarthritic joint. Pragmatically, it is important to realize that these nutraceuticals are not subject to the same stringent regulatory guidelines as pharmaceuticals. In fact, one study showed that as many as 84% of the human over-the-counter nutraceutical products vary widely in their composition and fail to meet their label claims. We recommend a high-quality product that combines the glucosamine and chondroitin sulfate ingredients with avocado-soya unsaponifiables (ASU). ASU decreases inflammation and, in human osteoarthritis trials, decreases pain scores and reliance upon nonsteroidal anti-inflammatory drugs (NSAIDs). Combined, these nutraceuticals (also referred to as “joint protective compounds” [JPCs]) have a role in joint health preservation and in the comprehensive management of OA.
NSAIDs decrease inflammation and, therefore, typically improve patient comfort and mobility in OA patients, but should not be seen as contributing to joint health preservation. Rare adverse reactions most commonly involve gastrointestinal, liver and/or kidney function. We recommend the medication be discontinued and immediate veterinary consultation sought if diarrhea, vomiting, melena, lethargy or lack of appetite is noted. Often, we recommend blood tests be performed prior to NSAID therapy and periodically throughout treatment.
Adjunctive systemic medications can decrease reliance upon NSAIDs or augment their effects in OA patients, but few of them have a role in joint health preservation.
Intra-articular (IA) injections of corticosteroids or hyaluronic acid have been advocated for osteoarthritic joints. Corticosteroid IA injection remains controversial, with some studies demonstrating adverse effects on cartilage while others demonstrate symptomatic relief and chondroprotective effects. In dogs with OA induced by cranial cruciate ligament transection, triamcinolone hexacetonide, 5 mg, IA reduced osteophyte size, cartilage erosions, and the histological severity of OA structural cartilage changes with no electron microscopic evidence of increased cell degeneration or death. Corticosteroid IA administration should be avoided immediately following arthroscopy because of increased risk of septic arthritis. Intra-articular injection of hyaluronan has been advocated for many species, including horses and humans, but its effects on naturally occurring OA in dogs have not been extensively reported. Short-term symptomatic relief has been reported in a small-scale study of dogs with naturally occurring OA following a two-injection protocol (3 weeks apart) with a high molecular-weight product. Hyaluronan’s mechanisms of action may be transient improvement in joint lubrication and its longer-lasting analgesic, pro-anabolic and anti-catabolic effects. Variation in molecular weight of the product, dosage, frequency of administration, as well as species and OA model evaluated may account for the variation in reported outcomes. Disadvantages of its use in dogs may relate to its relatively high cost, the apparent necessity of repeated IA injections, and lack of robust efficacy data reported in dogs.
Biologic therapies such as cytokine therapy, stem cell, and platelet-rich plasma (PRP) therapy are gaining advocates, especially when more conventional therapies have failed to restore patient comfort and quality of life. Upset of the critical balance of proinflammatory cytokines and anti-inflammatory cytokines is well recognized in the pathogenesis of OA. Conditioning of autologous serum from a whole blood sample has been used to stimulate the production of interleukin receptor antagonist protein (IL-Ra), IL-4 and other anti-inflammatory cytokines. Intra-articular injection of this autologous conditioned serum has resulted in significant clinical and histologic improvement in OA-affected joints. To circumvent the need for repeated IA injections, viral vector gene transfer technology has been employed to obtain sustained levels of IL-Ra. This approach has resulted in elevated intra-articular expression of IL-Ra, significant improvement in clinical parameters of pain and disease, preservation of articular cartilage, and beneficial histologic effects on synovial membrane and articular cartilage in equine and canine osteoarthritis models. Research and development for improved viral vectors is underway. Stem cell therapy involves stem cell isolation from various tissues including adipose and bone marrow and, in some instances, culture expansion. Injection of these cells into osteoarthritic joints may result in clinical improvement as compared to negative controls (sham injection), but few studies have evaluated this therapy compared to a positive control (current standard of care) therapy in the canine. In the absence of robust evidence for effectiveness over the current standard of care, the expense of stem cell therapy makes it difficult to justify for the majority of canine OA patients. PRP is defined as an autologous concentration of platelets in a small volume of plasma. PRP contains a concentration of critical growth factors that are actively secreted by platelets to stimulate cellular proliferation, migration, differentiation and matrix synthesis. These factors can affect chondrocyte metabolism, chondrogenesis, and improve cartilage healing in vivo. Several human studies show favorable clinical outcomes as compared to intra-articular injection of hyaluronic acid (HA). There is substantial variation in the preparation and formulation of autologous PRP, but affordable point-of-care preparation is certainly feasible.
Mechanical therapies for OA include pulsed ultrasound and shockwave. There is some evidence for the efficacy of shockwave therapy in the management of osteoarthritis. There is a need for more controlled studies in the canine to determine the efficacy relative to the current standard of care and recommended therapy protocols.
Surgical treatment, often required for effective management of OA, may involve joint stabilization, removal of cartilage/bony chips, or joint replacement. The relative importance and timing of surgery are variable depending upon the condition underlying the osteoarthritis. Typically, early intervention is indicated to maximize the surgical efficacy with regard to preservation of joint health.