Nonpharmacologic management of canine osteoarthritis: Part 2

Kirkby Shaw,Kristin;

Approximately 40% of dogs suffer from osteoarthritis (OA)-induced pain.¹ Proactive and multimodal management of OA should include pharmaceutical and nonpharmaceutical techniques.² The objective of this 2-part series is to summarize the evidence available for nonpharmaceutical methods of canine OA management.

Part 1 focused on the roles of weight management and exercise. Part 2 reviews therapeutic modalities, oral joint support supplements, and intra-articular injections. This is not a comprehensive review of all OA management options but rather a brief review of the evidence for commonly used therapies.

Therapeutic modalities

Therapeutic laser

The use of therapeutic lasers in medicine is termed photobiomodulation (PBM), which is commonly used in the management of pain. Experimental animal studies have demonstrated pain relief through release of serotonin, increased release of endogenous opiates, and blockage of afferent C fiber depolarization.³ Although lasers have been used extensively in human and veterinary medicine for pain relief, high-quality clinical data are sparse and conflicting.^4-6

There are at least 3 studies that support the use of PBM for dogs with OA.^7-9 Looney et al reported that with the protocol investigated, PBM was able to reduce pain, lameness, and nonsteroidal anti-inflammatory drug (NSAID) requirement in dogs with elbow OA in more treated dogs compared with placebo control.⁷ Alves et al reported reduced pain and improved function in police working dogs with hip OA when treated with PBM.⁸ Barale et al described increased activity levels and reduction in need for oral analgesics in dogs with hip or stifle OA receiving PBM.⁹

Laser therapy devices vary widely in output because there are countless variations in parameters that can be used. Laser devices and treatment protocols can differ based on wavelength, power, energy density, fluence (J/cm²), time of treatment delivery, and location treated.¹⁰ This is 1 reason for widely conflicting results seen across studies of PBM.

Pulsed electromagnetic field therapy

Pulsed electromagnetic field therapy (PEMF) uses nonthermal electromagnetic waves delivered to tissue to stimulate bone and soft-tissue healing; reduce inflammation, swelling, and edema; and decrease pain.¹¹Studies using PEMF in human patients with OA have shown reduced pain and improved function.^11,12 Studies in canine patients have reported beneficial effects of PEMF for postoperative analgesia, though there is currently limited evidence of PEMF for OA management in dogs.^13-15

The Assisi Loop and Respond PEMF Beds are 2 examples of therapies that can be utilized by pet owners in the home environment. As with the discussion around PMB, there are differences in the wave form and parameters that are delivered with different devices, leading to the inability to broadly apply results.

Extracorporeal shockwave therapy

Extracorporeal shockwave therapy (ESWT) is a modality in which high-energy sound waves are applied transcutaneously to increase tissue cytokine and growth factor expression and reduce pain associated with chronic conditions. In vitro and lab animal models have shown potential benefits to articular cartilage following ESWT, and improvement in clinical symptoms of OA has been reported in humans treated with ESWT.¹⁶ Conflicting data exist for use of ESWT in dogs with OA.¹⁷

A pharmacologic option for managing OA in dogs

Polysulfated glycosaminoglycan (PSGAG) (Adequan; American Regent Animal Health) is approved by the FDA for the management of OA in dogs. The mechanism of action of PSGAG is primarily through inhibition of catabolic enzymes that degrade articular cartilage.¹⁸ No studies have demonstrated regrowth of hyaline cartilage. Therefore, the earlier it is given in the OA process, the more effective PSGAG may be at slowing the progression of OA and decreasing pain.¹⁸ PSGAG has been shown to decrease lameness, pain, and inflammatory markers of OA in dogs with clinical OA.^19,20

PSGAG is labeled for intramuscular (IM) injection, though it is commonly administered by subcutaneous (SQ) injection to improve adherence and reduce the discomfort associated with repeated IM injections. The label dose is 4.4 mg/kg twice a week for 4 weeks. After this loading dose, many veterinarians will recommend weaning to the lowest effective dose for maintenance, though this is off-label use. Following IM administration, PSGAG reaches synovial tissue within 2 hours and persists in the joint for at least 3 days.²¹ The pharmacokinetics of PSGAG following SQ administration in dogs with OA are not known.

Joint support supplements

Oral joint support supplements

Oral joint supplements, also known as nutraceuticals, are not regulated by the FDA. Efficacy and safety studies are not required for commercial sale of these products. A plethora of human and veterinary products are available, but there is very little efficacy and even less or no safety data supporting their use.

A recent meta-analysis of 72 research articles on oral joint supplements concluded that there is clinical efficacy for Ω-3–enriched diets, Ω-3 supplements, and, to a lesser degree, cannabidiol.²² There is weak efficacy of collagen. This study also found a very marked noneffect of chondroitin glucosamine nutraceuticals, which led the authors to suggest that these products no longer be recommended for pain management in canine and feline OA.²²

Ω-3 fatty acids

Ω-3 fatty acid supplementation is a potential method of decreasing inflammation and pain associated with OA. Ω-3s can be provided through diets enriched with eicosapentaenoic acid and docosahexaenoic acid, natural sources (eg, anchovies or sardines), or fish oil supplements. The evidence for Ω-3 supplementation in dogs primarily comes from studies of therapeutic diets with high levels of supplementation and results are generally positive. These diets have been shown to improve weight-bearing, functional activity and reduce the amount of carprofen needed in dogs with OA.^23-25 There is currently limited evidence with fish oil supplements or whole fish, so it is uncertain whether the same clinical results will be seen with these diets.

Intra-articular therapies

Intra-articular (IA) injections are usually recommended if noninvasive therapies are insufficient in reducing pain associated with OA.²⁶ However, there may be some cases, such as elbow dysplasia, where IA treatment is recommended earlier in the disease process. There are several categories of IA therapy and new classes of products are being developed. No matter what product is injected, animals must be sedated for the procedure to ensure strict sterility and precise injection into the joint. The frequency of repeating injections will likely vary with the product used and even then, there are no clear guidelines in animals for frequency of treatment.

Studies have shown reduced pain and lameness in dogs with OA following injection with certain types of platelet-rich plasma, stem cell therapy, hyaluronic acid, steroids, and Synovetin OA (Exubrion Therapeutics), a conversion electron therapy device.²⁶

Conclusion

An OA management plan should include effective analgesia, weight management, regular exercise, and Ω-3 supplementation. Therapeutic modalities, intra-articular injections, and perhaps other oral joint supplements can be considered as adjuncts.

Other OA management options include cannabidiol, acupuncture, manual therapy, and assistive devices. These treatment options can be integrated into an OA management plan as adjunctive therapies. Surgery may also be indicated for the management of OA.

Kristin Kirkby Shaw, DVM, PhD, MS, DACVS, DACVSMR, is a small animal surgeon and rehabilitation specialist whose career has focused on bridging the gap between these 2 disciplines, with specific emphasis on treatment of arthritis. Shaw received her DVM, PhD, and MS degrees, and completed a small animal surgical residency at the University of Florida (UF) in Gainesville. She spent 2 years as a clinical instructor at UF and 9 years in referral practice in Seattle, WA. Shaw currently works for Zoetis as a specialist in pain management and osteoarthritis.