Bigstock photo Osteoarthritis (OA) is a formidable condition that veterinary health teams and caregivers face daily. OA significantly impacts our patients’ ability to move and their overall quality of life. The insidious pathological changes that occur to the components of the joint (joint capsule, synovium, synovial fluid, articular cartilage, subchondral bone, and the soft tissue support of the joint) cause very real outward clinical signs. The pain and swelling associated with OA lead to reduced active joint range of motion, off-loading of limbs, disuse muscle atrophy, and weakness. Proprioception also declines in patients with OA, which enhances injury risk. Further, as the activity level declines, the patient may gain weight, increasing whole-body inflammation and further aggravating the cycle of joint degeneration and discomfort. Veterinarians have a host of therapeutic options for their patients suffering from OA, including oral medications, targeted joint injections, supplements, weight management, as well as modalities, such as shockwave therapy or photobiomodulation, and acupuncture. Each therapy consideration has its unique advantages and precautions. However, when reflecting on the many beneficial effects of exercise in patients with joint pain, it is easy to see why our profession should promote it as a primary intervention. In fact, studies in the human field reveal that exercise is the most frequent non-pharmaceutical therapy prescribed for people suffering from OA.1 How does exercise help arthritic patients? Pain relief Engaging in physical exercise influences the levels of endogenous opioids and serotonin, stimulates the endocannabinoid system, and modifies the effects of N-methyl-D-aspartate (NMDA) receptors. These adjustments can lead to exercise hypoalgesia and a decrease in pain sensitivity, particularly in chronic pain scenarios, such as OA.2 Studies show that a duration of at least 20 minutes of moderate intensity exercise is necessary to boost levels of endogenous opioids or endorphins, which interact with opioid receptors to help reduce pain. Patients who cannot participate in moderate intensity exercise can still reap the benefits of exercise at a lower intensity, but the duration of exercise should be extended to a total of 60 minutes.3 Exercise is chondroprotective Intense exercise can impose excessive pressure on fragile joint tissues, increasing pain and harming cartilage and subchondral bone, thereby speeding up arthritis progression. Activities, such as jumping to catch a ball, playing sports that involve sharp turns, and engaging in rough physical play, can lead to painful flare-ups. It is crucial to inform clients about appropriate activity levels and necessary limitations to manage arthritis effectively over the long term. On the other hand, too little exercise has been shown to have an overall catabolic effect on articular cartilage, leading to faster progression of OA. Additionally, pets in a sedentary lifestyle have a higher risk of obesity, further amplifying the risk of OA progression. Research indicates that the right level of exercise protects the cartilage and slows down the progression of arthritis.4 Low to moderate intensity exercise is ideal for properly loading the articular cartilage to allow for the synovial fluid to bathe and nourish the cartilage. Exercise stimulates proteoglycan synthesis, an integral part of the extracellular matrix of the cartilage. Additionally, low to moderate intensity exercise lowers the pro-inflammatory cytokines in the joint (Table 1). Table 1. Physiologic Effects of Appropriate Intensity Exercise in Dogs with OA. Courtesy Dr. Kara Amtutz Improved muscle mass and strength With appropriately managed pain, exercise can be utilized to encourage patients to bear weight appropriately on the diseased joint. Weight-bearing and targeted strengthening exercises counteract disuse muscle atrophy. Additionally, sarcopenia, or age-related muscle atrophy, can be diminished in pets that exercise. Muscle contractions that occur during resistance training and walking regimens serve as a beneficial anabolic stimulus that promotes muscle fiber growth and increases strength. Interestingly, it has been found that exercise-induced muscle hypertrophy allows skeletal muscle to act as an endocrine organ, releasing specific myokines shown to cross the blood-brain barrier, improving memory and cognition in older humans.5 Improved cognition and vitality OA is a condition that can impact dogs of any age, but its occurrence tends to rise significantly as dogs grow older, with as many as 80 percent of dogs showing signs of it by age eight.6 Canine cognitive dysfunction syndrome (CDDS), which resembles Alzheimer’s disease in humans and is marked by gradual neurodegeneration, is also found in older dogs. Dogs that are less active physically are at increased risk of developing CDDS.7 A large observational study of more than 11,000 dogs mirrored this finding in that dogs that maintained physical activity had improved cognitive outcomes.8 Human literature supports these findings as well, with evidence that exercise also helps to relieve depression.9 Client education Pet caregivers are often fearful of encouraging exercise for their pets suffering from OA because they are concerned that it will exacerbate the pain. The veterinary health team should calm these fears with specific exercise guidelines and educate the client that too little or too intense exercise can cause problems, but just the right amount will make the pet feel better. Appropriate exercise Walking, light hiking, and swimming are all excellent choices when looking for low- to moderate-intensity exercises to protect the joints, reduce pain and inflammation, improve active range of motion, and maintain lean body mass. Resistance exercise, such as using weights, is highly recommended in humans for strengthening and building muscle. While it may be difficult to get a dog to lift a dumbbell, we can use their body weight as resistance and perform targeted therapeutic exercises, such as down to stand, stepping over low objects, front feet up on an elevated surface, etc. (Figures 1 and 2). Figure 1. Dog stepping over cavaletti rails to improve active joint range of motion, improve proprioception, balance, and strength. Photo courtesy Dr. Kara Amstutz Figure 2. Dog standing with thoracic limbs elevated, shifting weight to the pelvic limbs to increase strength. Photo courtesy Dr. Kara Amstutz Exercise goals A study in dogs with hip dysplasia and secondary OA found that 60 minutes of exercise provided a superior reduction in lameness scoring than only 20 minutes of exercise.10 Therefore, 60 minutes of low to moderate intensity exercise five days a week is a great goal. Many pets and their caregivers who have not been exercising regularly need to gradually build up to their exercise goals. It is recommended to start with shorter, more frequent walks and then gradually increase the total walking time to 60 minutes. This can be adjusted to fit the caregiver’s schedule, such as four 15-minute walks or six 10-minute walks. Resistance training three times weekly with targeted strengthening exercises can be incorporated into the plan to improve strength and counteract muscle atrophy. Typically, two to three sets of six repetitions are recommended (Table 2). Table 2. Courtesy Dr. Kara Amstutz It is important to explain to caregivers what to watch for if fatigue is setting in. Forcing a pet to exercise once it is fatigued can increase the risk of injury. Failure to maintain normal posture, trying to walk away, excess panting, or refusal to do the exercise are all indicators that the pet should be given a break and tried again later. Don’t forget to prescribe exercise With so many therapeutic options available for dogs with OA, some of which may have negative side effects, providing a strong exercise recommendation to your clients is a wise choice. No other single therapy offers the same benefits: it relieves pain, protects cartilage, assists with weight loss, builds muscle, and improves cognitive function. Best of all, exercise comes at no financial cost. All that is required is time, commitment, and consistency to enhance the health and long-term vitality of our patients. Kara Amstutz, DVM, DACVSMR (Canine), CVA, CVPP, CCRT, is the director of Clinical Education at the Canine Rehabilitation Institute. Dr. Amstutz also owns and operates Momentum Veterinary Sports Medicine and Rehabilitation, a private specialty practice focusing on pain management and pet mobility in Springfield, Mo. References Leong D.J. and Sun H.B.(2014) Osteoarthritis - Why Exercise? Journal of Exercise Sports & Orthopedics. 1(1):04. Belavy D.L., Van Oosterwijck J., Clarkson M., Dhondt E., Mundell N.L., Miller C.T. and Owen P.J. (2021) Pain sensitivity is reduced by exercise training: Evidence from a systematic review and meta-analysis. Neuroscience and Biobehavioral Review Jan;120:100-108. Ali A.H., Ahmed H.S., Jawad A.S. and Mustafa M.A. (2021) Endorphin: function and mechanism of action. Science Archives 2(1), 9-13. Liu J., Jia S., Yang Y., Piao L., Wang Z., Jin Z., Bai L. (2023) Exercise induced meteorin-like protects chondrocytes against inflammation and pyroptosis in osteoarthritis by inhibiting PI3K/Akt/NF-κB and NLRP3/caspase-1/GSDMD signaling. Biomedicine & Pharmacotherapy, 158, 114118. Scisciola L, Fontanella RA, Surina, Cataldo V, Paolisso G, Barbieri M. (2021) Sarcopenia and Cognitive Function: Role of Myokines in Muscle Brain Cross-Talk. Life; 11(2):173. Johnston, S.A. (1997) Osteoarthritis: joint anatomy, physiology, and pathobiology. Veterinary Clinics of North America: Small Animal Practice, 27(4), pp.699-723. MacQuiddy, B., Moreno, J. A., Kusick, B., & McGrath, S. (2022) Assessment of risk factors in dogs with presumptive advanced canine cognitive dysfunction. Frontiers in Veterinary Science, 9, 958488. Bray E., Raichlen D., Forsyth K., Promislow D., Alexander G., MacLean E., and Dog Aging Project Consortium. (2023) Associations between physical activity and cognitive dysfunction in older companion dogs: results from the Dog Aging Project. GeroScience, 45, 645–661. Ahn, J., and Kim, M. (2023) Effects of exercise therapy on global cognitive function and depression in older adults with mild cognitive impairment: A systematic review and meta-analysis. Archives of Gerontology and Geriatrics, 106. Greene L., Marcellin-Little D., & Lascelles D. (2013) Associations among exercise duration, lameness severity, and hip joint range of motion in Labrador Retrievers with hip dysplasia. Journal of the American Veterinary Medical Association, 242(11), 1528-1533.
