Clinical Notes: Considerations in the Management of Osteoarthritis

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Osteoarthritis (OA) is a common condition in dogs, with 1 study showing ≈40% of dogs 8 months to 4 years of age having radiographic signs consistent with OA in ≥1 joint.¹ Of those dogs with radiographic signs of OA, ≈60% had clinical signs of joint pain apparent on veterinary examination.¹

These statistics not only highlight how common OA is, but they also stand in contrast with the traditional view of OA as an age-related disease of geriatric pets. Instead, OA commonly begins early in life, often being triggered by developmental joint disease or joint trauma.² Additional risk factors such as diet, obesity, genetics, and breed can all influence the development and progression of OA.²

Osteoarthritis: A Progressive Clinical Disease

OA is a global disease process affecting the entire joint, with articular cartilage damage being just one part of the issue.³ Inflammation and crosstalk between the many different tissues within the joint (ie, joint capsule, synovium, synovial fluid, cartilage, subchondral bone) drive this process and result in the development of pain, continued inflammation, and clinical disease.³

OA is a progressive, cyclic disease that generally worsens over time, with joint pain and inflammation leading to decreased activity, periarticular fibrosis, loss of range of motion, weight gain, and muscle atrophy.³ These changes then lead to further reduction in activity, further muscle atrophy and weight gain, additional inflammatory mediators, and increasing joint pain and inflammation, where the cycle begins again.

Prompt diagnosis and aggressive treatment are critical to trying to slow the progression of disease and interrupt this cycle, as early intervention may help delay or even prevent joint failure.³ Dogs at high risk for developing OA should be identified early on, and for dogs that are already demonstrating clinical signs of OA, identifying their stage of disease is necessary to begin appropriate management.

Osteoarthritis Staging

Staging of OA provides an objective patient assessment that can help in guiding therapy choices and monitoring disease progression. The Canine OsteoArthritis Staging Tool (COAST) is a widely recognized tool that can offer significant benefits for veterinarians, clients, and patients. The COAST tool incorporates both owner assessments and veterinarian clinical assessments to stage both preclinical dogs, “at risk” dogs, and dogs with clinical signs of OA.⁴ Dogs are assigned a COAST stage from 0 to 4 based on veterinarian and owner assessments (see Table).

TABLE: Coast Stages⁴

Using the COAST staging tool allows for standardized scoring of OA severity, in turn allowing veterinarians and pet owners to determine a pet’s baseline and track progress over time.

Osteoarthritis Management Strategies

Once an individual patient’s COAST stage has been identified, it is important to work with the owner to define the goals of treatment. Each patient should be considered as an individual, and unique treatment priorities should be discussed with the owner. Common treatment goals include improving quality of life and decreasing pain, but owners may have additional goals that are specific to their individual pet or lifestyle. For example, they may prioritize being able to participate in a specific activity with their dog to help maintain the human–animal bond. Open discussion with clients is essential to identifying these desirable and reasonable treatment goals. In addition, the practitioner’s preferred strategy for managing OA should be identified; ideally, this should include modulating, minimizing, and/or eliminating inflammation.³

Successfully managing OA requires a multimodal approach and understanding when the various strategies should be incorporated. OA cannot and should not be addressed through a single medication or treatment. Instead, multiple interventions are required for successful management and can include a combination of lifestyle and nutritional modifications, NSAIDs, biologics, and adjunct therapies, all of which can offer benefits based on the individual patient’s needs and owner preferences.

Lifestyle & Nutritional Modifications

Lifestyle modifications are a key step in the multimodal management of OA. All dogs with OA, whether in stage 1 or stage 4, can benefit from lifestyle modifications. Weight optimization is essential, considering the role that obesity plays in many cases of OA, and is best achieved after controlling pain and gradually increasing exercise.⁵

All dogs with OA can benefit from daily activity, which can be broken into daily playtime and daily exercise. Daily playtime is the time spent when the dog is running, jumping, chasing, etc; however, the duration and frequency of daily playtime should be limited, with a stronger focus being on daily exercise. A daily exercise plan should be customized to the dog’s overall health and degree of osteoarthritis. For example, a goal should be to work up to two 20-minute walks daily, as activity of this length and frequency can aid in weight management and help maintain limb function. This plan should be developed through collaboration with the owner to ensure it is practical and reasonable for both the patient and the owner. Nutritional interventions can also provide benefits to the OA patient.

Administering eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA), providing a minimum daily dose of 100 mg/kg of DHA/EPA, or providing a diet supplemented with these ingredients can be considered in all COAST stages of OA,² as these ingredients have been shown to offer benefits in the adjunctive treatment of dogs with OA.⁶

NSAIDs

For dogs with clinical signs of OA (COAST stage 2 or higher), additional treatments beyond lifestyle modifications are recommended to control pain and inflammation.^2,7

NSAIDs are the best tool available for the management of inflammation and are thus considered a first-line treatment in dogs with stage 2 or greater OA.^2,3 An NSAID should be administered daily for 1 to 4 months, after which time tapering or reducing the dose frequency can be considered based on patient response and NSAID tolerability as assessed during regular rechecks.³ Long-term NSAID use has been shown to be effective and safe in dogs,⁸ and some patients, particularly those in COAST stage 3 to 4, may benefit from long-term daily NSAID administration.^2,3

When it comes to choosing an NSAID, using one that targets prostaglandin E₂ receptor 4 (EP4 receptor antagonist) can be advantageous, as these have been shown to effectively control OA without blocking production of prostaglandins.⁹ Conversely, cyclooxygenase-inhibiting NSAIDs are less targeted and work by inhibiting the production of a variety of prostanoids. Galliprant™ (grapiprant tablets) specifically targets the EP4 receptor, which is the primary mediator of prostaglandin E2-induced inflammation, nerve sensitization, and pain.⁹ Because grapiprant blocks a single downstream receptor rather than decreasing production of prostaglandins, it helps to preserve homeostatic function and reduce the impact on organ health.^9,10

Since Galliprant™ (grapiprant tablets) received FDA approval, >25 million dogs in the United States have been treated with grapiprant. Adverse events, including vomiting and diarrhea, occurred in <1 in 10,000 reports (very rare based on Council for International Organizations of Medical Sciences classification), according to unpublished adverse event reporting data. Many of these signs occurred in <1 in 100,000 reports.^11,12

Monoclonal Antibodies

Anti-nerve growth factor monoclonal antibody (anti-NGF mAb) is another therapeutic consideration for dogs with OA. This treatment works by blocking the activity of NGF, which contributes to neurogenic pain in OA.^13,14 Bedinvetmab, an available anti-NGF mAb, is labeled for the control of pain associated with OA.¹⁵ Patient selection and the recommended timing of anti-NGF initiation may be clinician-dependent, with varying expert views.^2,7 A recent unpublished study in a canine model of acute synovitis revealed that grapipiprant and bedinvetmab provided the same degree of pain control, as measured by force plate gait analysis; however, grapiprant was associated with greater reductions in joint swelling.¹⁶ This observed difference in anti-inflammatory activity is consistent with the differing mechanism of action and corresponding FDA-approved indications for each drug.

Adjunct Therapies

Although lifestyle changes and pharmaceutical therapies are a strong foundational starting point in the management of pain and inflammation in many dogs with OA, periodic flare-ups may still occur. These flare-ups do not indicate that the current treatment protocol is not working. Instead, the patient’s current treatment regimen should be continued and adjunct treatments considered to help manage the flare-up. Adjunct treatment options include oral analgesics (eg, amantadine, gabapentin), intra-articular injections (eg, hyaluronic acid, corticosteroids, platelet-rich plasma), physical rehabilitation, and shockwave therapy. These adjunct treatments may be used on a short-term basis until the clinical signs of OA have abated, or a longer course of treatment may be necessary depending on patient response.

Client Communication

Managing OA requires effective and frequent client communication, and regular recheck examinations are essential to determine whether prescribed treatments are proving to be safe and effective for a given patient. The importance of regular follow-up should be emphasized when educating owners of dogs with OA; if a dog experiences an OA flare-up, follow-up examination can allow for patient assessment and the discussion of additional measures to alleviate pain and improve the dog’s quality of life.

Owners must also understand that, when used according to a veterinarian’s directions, long-term NSAID use in dogs has been shown to be a safe and effective means of preventing ongoing inflammation and reducing the frequency of OA flare-ups. In addition, owners must understand that flare-ups will occur in dogs with OA, despite effective management. A flare-up does not mean that the current treatment is not working; it simply means the dog needs an adjunct treatment (on a temporary or long-term basis). Owners should be educated on how to recognize flare-ups, and the veterinary team should discuss treatment options with them so they feel prepared for that eventuality. Finally, it should be reiterated that OA management is stepwise; treatment begins with lifestyle modifications, and other treatments are layered in depending on the patient’s needs.

Conclusion

Osteoarthritis is a common sequela of developmental disease, joint injury, and/or obesity. Once early signs of OA arise, this condition is likely to gradually progress over time. Prompt diagnosis can allow for early interventions, and COAST can help facilitate both early diagnosis and accurate patient monitoring. The veterinary team should work with clients to develop a multimodal treatment plan at the first signs of OA. With regular rechecks and effective client communication, these interventions can help prolong quality of life in dogs with OA.

This article was developed with the help and expertise of David Dycus, DVM, MS, CCRP, DACVS-SA, Ortho Vet Consulting, Severn, Maryland.

SELECT IMPORTANT SAFETY INFORMATION

If Galliprant is used long-term, appropriate monitoring is recommended. Concomitant use of Galliprant with other anti-inflammatory drugs, such as COX-inhibiting NSAIDs or corticosteroids, should be avoided. See important safety information.

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