Reframing the understanding of medical orthopedics, pain management, and osteoarthritis
This content is sponsored by Hill's and Boehringer Ingelheim.
Camellia used to enjoy the feeling of the wind pressing against her face as she ran through fields with her mouth open, tongue loose, and eyes slightly squinted. Now as a 3-year-old female spayed Labrador with bilateral coxofemoral osteoarthritis, she no longer enjoys her favorite cursorial pastime. She was diagnosed with increased hip laxity and bilateral hip dysplasia at 12 months of age. Surgical treatment was not an option for her family then and still isn’t now. Like a staticky radio in the background, the pain in her hips is constant and tough to ignore, which hasled to significant mobility issues. Without exercise, Camellia now has a body condition score of 8/9, and the tingling pain in her hips feels similar to licking the poles of a 9V battery. She is restless, frustrated, and has a look of defeat.
Osteoarthritis-associated pain is debilitating, chronic, and can be invisible, especially if you don’t know what to look for. When canine family members have joint pain, it creates a frustrating duality. It’s painful for the dog and severely disrupts the family-animal bond. Surgical treatment options for osteoarthritis-associated pain are limited, which is often punctuated by financial restraints or medical comorbidities.
The joint is an organ, and osteoarthritis is a disease of this organ.1 In an osteoarthritic environment, there is a cascading and relentless attack to the joint and periarticular tissues by inflammatory mediators, which causes joint and tissue remodeling. The result of these pathologic changes can be referred to as joint failure. In both priority and understanding, the approach to medical orthopedics has evolved in the past 30 years. To understand the damage and sequelae of osteoarthritis pain, it is important to get close and familiar with this disease. It’s vital to understand the foundation and inner mechanisms of osteoarthritis pain. Being well acquainted with the pathophysiology of pain, pain assessment tools, and multimodal treatment options that are available is essential to combating this condition.
A shift in language and terminology is at the core of a new understanding of this disease. When terms such as degenerative, wear and tear, and bone on bone are used to discuss osteoarthritis in dogs, it may change a family’s attitude toward pet exercise. Many families may elect to exercise their dogs less out of fear that it could lead to further injury or pain. Their enthusiasm to bond with their canine family member through exercise begins to wane. This leads to prolonged bouts of recumbency, weight gain, and declining health.
Instead, Camellia’s veterinary team began the conversation, helping her family understand some of the intricacies of pain science. The team emphasized that cartilage is a dynamic structure. In the right environment and with progressive loading, cartilage can change. New terminology such as wear and repair and load and grow were substituted for the superannuated terminology to highlight the need for rehabilitation, exercise, and decrease in global systemic inflammation.
It is axiomatic that an ounce of prevention is worth a pound of cure, and it is important to have a similar approach to treating pain. Camellia’s pain has become unbearable, now forcing her veterinary team to respond reactively or play catch-up, which is suboptimal. A proactive preventive treatment philosophy that both preempts pain and is patient specific serves as bulwark against increasing nociceptive stimuli.
Camellia is not alone. Unfortunately, more than 40% of dogs will experience osteoarthritis-associated pain at some point in their lives. Although Camellia was battling hip pain, many dogs will experience multijoint pain, which creates a constellation of agony for those affected.
Camellia would have been more comfortable if her osteoarthritis pain was treated before it became so severe. Understanding and observing the clinical signs associated with osteoarthritis pain is essential for early interventional treatment. Pain assessment in animals is no easy task. Because of the myriad ways patients demonstrate pain, measuring pain in dogs is challenging even among the most experienced clinicians. The family, veterinarian, and veterinary team are the most critical triumvirate for managing pain.
Medical history provided by the owners is gold. Similar to any valuable mineral, good nuggets of valuable information have to be mined. Asking focused, specific questions related to changes in behavior, ability to navigate objects (eg, stairs), ability to jump, and exercise tolerance will help uncover hidden gems of information. Simultaneously educating clients to both the difference and the devastating impact of chronic vs acute pain is an integral part of the pain assessment. Moreover, client education may create a positive feedback loop, which may elicit more comprehensive medical history once the identification and the importance of treating pain is fully appreciated. Activity monitors can also help to bridge the gap between families and the veterinary team when assessing response to treatment.2
The physical examination is a conver- sation between the patient and the veterinarian. As a specific movement is performed, the patient will communicate whether that movement is painful. A thorough physical and orthopedic exam is an art. Gentle handling, meticulous observations, and exquisite behavioral knowledge helps improve the experience for the patient. An enduring commitment to improving and refining the orthopedic exam is an essential component to pain assessment and allows for a more complete physical exam. For example, the perception of pain has been shown to be heightened by anxiety,3 therefore greater attention should be paid to anxiolytics and anxiety-reduction techniques to decrease the spurious pain behaviors during orthopedic exams.
Collaboration and coordination among the veterinary team are 2 indispensable components of pain management. Veterinary technicians, doctor’s assistants, receptionists, and practice managers all serve a role in educating clients about the importance of pain management, coordinating recheck schedules, and enhancing the basic knowledge of various therapeutic modalities. Daily and monthly rechecks are needed to stay proximate and familiar to the subtle changes of every patient and, most importantly, response to therapy. It’s extraordinarily helpful to have a dedicated, scheduled, and personalized in-person session for client education on pain science. Clients will have the ability to ask questions about the new information they are processing, and it gives the medical team time to ask questions so that the treatment plan can be individualized. When it comes to pain management, progress typically begets more progress; in that, intentional and compassion-centered care creates a stronger veterinary-client-patient relationship, which leads to better communication.
Camellia has been communicating her pain to her family for months— possibly years—but her family was slow to notice. Not only was she particularly talented at compensating for her chronic pain, but her family also simply didn’t know what to look for. The old saw, “chronic pain is less squeaky and more sneaky,” signifies that the hallmarks of acute pain differ from chronic pain. For example, in acute pain scenarios, patients may vocalize in response to focal pressure, whereas the signs of chronic pain can be more gradual. There are also clear distinctions between how acute and chronic pain are measured. Clinical metrology instruments (CMIs)4 are questionnaire-style tools that give a standardized scale to measure response to pain management. Generally, acute pain is most often objectively measured using clinical observations, including physical exam findings, behavior (ie, appetite, observation of demeanor, behavior, and palpation), and occasionally CMIs. Interestingly enough, no CMIs exist for acute pain assessment for families at home. Consequently, all forms of pain assessed by families at home, including acute pain, acute-on-chronic pain, and chronic pain, rely wholly or in part on at-home observations. For this reason, client education for families like Camellia’s is essential. Clinical signs of chronic pain, such as difficulty with transitions (eg, rising, sitting, or shifting weight), awkwardness when walking, and lameness, can be gradual and insidious in their onset.
For Camellia, the owners noted that she seemed to have difficulty rising after rest. They reported that when she started to move, her hips seemed to be “locked in place,” then she gradually began to warm out of the stiffness, and she seemed fine after exercise. She also seemed to be irritable with interactions with children and other dogs. A few accidents of inappropriate urination were also reported, all of which could be attributed to rising osteoarthritis-related pain. Fortunately, veterinary teams can create uniformity in their questioning of families by incorporating the Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs, and Sleep and Nighttime Restlessness Evaluation questionnaires into their medical practice.
Once joint pain is suspected, diagnostic tools can be used to confirm the suspicions. When Camellia was 13 months of age, she presented to the hospital for a suspected foreign body ingestion. Abdominal radiographs were taken, and the attending veterinarian noted bilateral hip osteoarthritis at the periphery of the radiograph. When questioned, Camellia’s family reported no clinical signs. She continued enjoying all her favorite activities, including sprinting for frisbees, diving off the lake pier, and episodic frenetic random activity periods. For Camellia, there are a host of tools that can help to confirm the presence of joint pain, including radiographs, ultrasound, advanced cross-sectional imaging, CT, and MRI. In some settings, there are even more sensitive tools for assessing lameness, including force plate and pressure plate analyses. It was critical to impress on the family that joint pain on palpation and radiographic signs of osteoarthritis correlate poorly.5 There are patients who will show marked osteoarthritic changes without readily ostensible clinical signs. Conversely, there are patients who demonstrate relatively minor osteoarthritic changes on radiographs, but those changes drastically impact their quality of life. Fortunately, her veterinary team plans to adhere to the old saw, “treat the patient and not the x-rays.”
Pain pathways are complex and our response to it must be equally as sophisticated. A multilayered, thoughtful, and considerate approach lies at the heart of a multimodal treatment strategy. The key to this strategy is to harness the power of multiple analgesic medications to target different receptors along the pain pathway. The main benefit of this strategy is not only improved analgesia but also decreased adverse effects.
One of the most powerful steps Camellia’s family can take to help her is to optimize her weight. It’s heart- breaking to see any animal in pain. The urge to prioritize pharmaceuticals over nonpharmacologic interventions can be strong, especially when in search for immediate relief. However, weight loss has a potent impact on both pain relief from osteoarthritis and overall longevity.6,7 Evidence of this from veterinary studies, and others from human medicine, are strong and compelling. Reducing Camellia’s body condition score will decrease the rate of osteoarthritic progression, lower the deluge of circulating inflammatory cytokines, and allow her to live a longer life. Furthermore, restoring Camellia to a normal body weight will help address neuropathic pain that has developed secondary to osteoarthritis-associated pain.
Camellia’s family placed her on a therapeutic food containing omega-3 fatty acids and L-carnitine, which, according to studies, have shown to help patients lose weight, decrease oxidative damage, and possibly enhance the efficacy of anti-inflammatories.8,9 The gut-joint axis as it relates to osteoarthritis was also discussed. This portion of the conversation spotlighted the preliminary yet sound evidence from animal studies that revealed an association between diet, gut dysbiosis, radiological severity of osteoarthritis, and clinical signs.10 Although diet and exercise are considered the one-two punch for weight loss, diet is more effective than physical activity for controlled weight loss in overweight dogs like Camellia.4 To be sure, exercise has a host of benefits for dogs, including overall joint health and mental health. However, the emphasis on a proper diet cannot be understated when weight loss is the goal.
Camellia’s family started a low-impact exercise program consisting of 15-minute walks twice daily, and they have plans to also enroll her in a rehabilitation program. The “warming out” of her stiffness that her family noticed is grounded in the pathogenesis of the disease. Osteoarthritis in her hips has triggered a progressive loss of joint cartilage, synovial inflammation, formation of osteophytes, and subchondral bone remodeling.11 The smooth gliding effect of the cartilage and the integrity of the joint has broken down, causing her to feel stiff, painful, and it compromises her overall range of motion.12 For Camellia, it hurts to move, which has resulted in a loss of muscle tone, ultimately exacerbating her clinical signs.13 Joint mobilization, rehabilitation, and exercise can help. A regular underwater treadmill rehabilitation program will decrease the loading on Camellia’s joints. The increased resistance from the water will increase muscle mass and energy expenditure, which is helpful to an overweight Labrador with hip dysplasia and osteoarthritis.
The inflammation and pain caused by osteoarthritis can be searing and pervasive. Nonsteroidal anti-inflammatory drugs (NSAIDs) are a first-line treatment for overweight dogs who are experiencing osteoarthritic pain like Camellia. NSAIDs help to address degenerative and inflammatory pain pathways within the joint,14 and long-term use of NSAIDs have proven to be more effective the longer they are used.15 Although she is likely to improve with the use of NSAIDs, their potential for adverse effects, including liver, renal, and gastrointestinal toxicity, cannot be ignored. To mitigate risk of adverse events, dose reduction can be considered; however, individual responses vary.16
The future is bright in the campaign to fight osteoarthritis-associated pain. Despite the dearth of data on efficacy, positive anecdotal reports have made gabapentin one of the most popular medications in veterinary medicine for treating chronic pain.17 An emerging therapy that could become a first-line treatment for Camellia’s osteoarthritis-associated pain is anti-NGF monoclonal antibodies. Currently approved for use in cats in the United States, Camellia—and dogs across the nation— could soon have a novel pain relief treatment that specifically targets NGF. Acetaminophen has shown to be safe in dogs,18 but its use in chronic pain is controversial.19 Intra-articular treatments including hyaluronic acid, platelet-rich plasma, stem cell therapy, and radioisotope of Tin-117m all can be considered metaphorical arrows in the quiver in the fight against osteoarthritis-associated pain. In fact, when combined with physical therapy, platelet-rich plasma is more effective than physical therapy alone.20 Further research into cannabinoid compounds and TRPV1 agonists, such as capsaicin and resiniferatoxin, may be new offerings in the arena of chronic pain management.21
Multimodal treatment can be complicated as much as it is valuable. When Camellia’s family conducted internet research into treatment modalities for canine osteoarthritis, they felt enmeshed in a labyrinth of options that were difficult to negotiate. Fortunately, their veterinary medical team gave Camellia’s family a brief, overarching review of current and emerging osteoarthritis treatment strategies, then discussed a tiered and coupled approach to osteoarthritis treatment.17 Tiered signifies that during treatment, additional therapeutic modalities will be incorporated into the regimen depending on response. Those with the highest impact on osteoarthritis and the lowest impact on the family will be prescribed first (ie, NSAIDs). A coupled treatment strategy employs the use of a nonpharmacologic treatment and a pharmacologic treatment together (eg, NSAIDs and weight loss program, platelet-rich plasma and rehabilitation therapy, gabapentin and low-level laser therapy).
For the first tier, Camellia’s veterinary team prescribed meloxicam oral suspen- sion as a first-line treatment NSAID for a fine-tuned dose reduction in the future. The meloxicam oral suspension prescription was coupled with both a weight optimization and structured exercise program, including daily walking.22 The second tier proposed to Camellia’s family was the addition of amantadine because of its effectiveness when combined with an NSAID for chronic pain.23 That pharmacologic therapy was coupled with the nonpharmacologic therapy of low-level laser therapy because of its potential impact at reducing pharmacologic analgesic therapy.24
Chronic pain secondary to osteoarthritis can have diverse presentations of pain, and the number of treatment options can seem overwhelming to families. That initial in-person client education on pain science is essentially the first step in treatment. Education on this topic is vital to reframe conversations on osteoarthritis, challenge myths, help clients understand prognoses, and understand the variety of treatments available. For Camellia, treatment for her osteoarthritis will be lifelong. Her journey to a more comfortable life will be guided by standardized tools, evidenced-based medicine, a dedicated veterinary team, and steady and consistent communication. An open dialogue with her veterinary team will help her family be the best stewards of her care. These vital conversations provide opportuni- ties to reassess and adjust her treatment plan according to her specific response. Reframing the conversation around osteoarthritis away from fatalistic language and toward more dynamic language will help underscore the true physiology of joint remodeling. Bioplasticity is the theory that all the systems in the body—from the muscles to skin and joints—have the ability to adapt to the demands placed on them. Based on the evidence of various therapies, osteoarthritic joints do have the ability to improve. The changes in the joint are not immutable; a brighter future can be constructed.
An early, proactive, and preemptive response to chronic pain through a tiered approach using a combination of pharmacological and nonpharmacologic interventions not only gives Camellia’s family access to compassionate care, but it also gives her the best chance to manage pain and allow the wind to glide across her face once more.
Courtney A. Campbell, DVM, DACVS-SA, is a board-certified veterinary surgeon who specializes in orthopedic, soft tissue, and minimally invasive surgery. He practices at VetSurg in Ventura, California. He is also a host, author, producer, and content contributor for Vet Candy. Campbell is the host of 3 popular podcasts: Anything Pawsible, The Dr. Courtney Show, and Vet Mysteries with Dr. Courtney. Dr. Campbell has been dedicated to veterinary journalism for the past 10 years. He had the honor of co-hosting Pet Talk, a first-of-its-kind talk show on Nat Geo Wild. He was awarded the Excellence in Journalism and Outstanding Contributions to the Pet Industry Award at the Global Pet Expo in 2020. He shares his life between veterinary surgery, veterinary journalism, and exploring the depth of the human-animal bond.