Canine Osteoarthritis - what is it, what causes it and how can we manage it?
Osteoarthritis affects 20% of the UK canine population and is a condition that we have all heard of but what is it, what causes it and how can we manage it?
WHAT IS OSTEOARTHRITIS?
Osteoarthritis (OA) is a synovial joint disorder involving cartilage, bone and the synovial membrane. Onset of OA is usually slow and is characterised by the progressive degeneration of articular cartilage, leading to joint pain, inflammation, synovial effusion, limited range of motion and consequently impaired function.(1) Unremitting joint pain and inflammation can cause adaptive muscle guarding and altered weight-bearing to protect the affected limb from further discomfort and injury.(2) Compensatory muscular adaptations are often characterised by muscle weakness, joint instability, altered limb loading and increased joint stiffness.(3) The maladaptive musculoskeletal response may also alter the animals way of moving, leading to increased loading of other structures and secondary injury, OA or muscle stiffness.(1; 4) An example of muscle stiffness secondary to OA is demonstrated in dogs with hip OA that draw their limbs forward using their spinal muscles rather than flexing and extending the hip joint, leading to hypertonicity and trigger points within the spinal muscles.(5) Major presenting signs of OA are lameness, stiffness, exercise intolerance or an unwillingness/inability to perform certain activities, such as jumping into the car or climbing up the stairs. The most common presenting sign of OA is stiffness following inactivity, whereby the animals lameness appears to resolve during exercise and worsen after a period of rest.(6)
WHAT CAUSES OSTEOARTHRITIS?
Several factors can cause an individual to be susceptible to arthritis, these include genetics, age and systemic factors such as obesity. Furthermore joint instability or injury can exacerbate a susceptible individual. Old age is reported to cause ‘primary OA’ whereas obesity and injury are reported to cause ‘secondary OA’, the most common form. Any disruption to a joint has the potential to trigger OA, the biggest disruption being injury. Injury to any of the joint structures (bones, ligaments, tendons, bursa or synovial membrane) that results in inflammation frequently lead to progressive joint degeneration and post-traumatic OA as a result of the biochemical cascade associated with inflammation. Post-traumatic OA can be seen in any age of animal that has experienced joint injury, either from acute injury due to an obvious trauma or due to repetitive overloading of the articular surface. Obesity promotes the development of OA in three ways. The extra weight puts unnecessary additional pressure on the joints which promotes the degeneration of cartilage. The presence of fat physically restricts joint motion and consequently reduces joint health by reducing the production and distribution of synovial fluid, the joint lubricant. Lastly, adipose tissue release enzymes that promote inflammation within joints and triggers the development of OA. Older animals have a reduced ability to maintain articular cartilage health and a reduced ability to repair worn cartilage, therefore predisposing them to OA. Furthermore, their reduced activity level can predispose them to OA as their joints are moving less, leading to reduced synovial fluid production and distribution within the joint and consequently reduced joint health.(6)
OA management requires a combined multimodal approach through controlled exercise, weight management (in overweight cases), dietary management, medical management, physiotherapy and in some cases surgery. Regular controlled exercise is beneficial for the osteoarthritic patient, however, complete rest or extreme levels of exercise can be detrimental. It therefore requires a healthy balance. It is advisable to avoid activities that require sudden extreme bouts of exercise, such as chasing a ball or agility and to instead provide more controlled exercise in the form of regular but short on lead walks. During a flare-up of OA it is advisable to reduce the length of walks but maintain the frequency.(6)
Overweight or obese dogs that undergo weight loss have a significantly improved way of moving, improved level of exercise and reduced chronic pain. Furthermore these benefits can be achieved after a modest amount of weight loss (6%), which it is reasonable to achieve in just two to three months.(7; 8; 9) A well accepted method of weight loss is a combination of dietary energy restriction and increased physical activity. As weight loss takes time it should not be the only method of OA management and often you find that an animal loses weight more effectively once their levels of pain have been addressed as reduced pain during activity will increase levels of voluntary activity. Surgical management for OA can immediately improve an animals level of exercise due to reduced pain and improved mobility, however, if surgery is delayed until after a period of weight loss risk of surgical complications will be reduced of you may find that surgery is in fact no longer required.
Purpose-formulated weight loss diets are essential as they provide the right bulk of food to meet the animals hunger levels and the correct levels of nutrients, while containing less calories. Furthermore they often supplement in essential nutrients that promote metabolism and reduce hunger levels. If we continue to feed their normal diet but reduce the quantity fed there is a risk of malnutrition as other essential nutrients will also be reduced. Food intake should be measured accurately to avoid over feeding. This can be done by weighing their food rather than using a scoop. Owners should avoid feeding their animal table scraps and treats when they are trying to achieve weight loss, however, some treats (particularly ones with other benefits such as dental chews) can be given provided that the calorie content is taken into account and deducted from their normal food. Feeding method can also be considered as more complex methods, such as a puzzle feeder, slow down the rate of feed intake which reduces hunger and improves enjoyment. The animals progression should be monitored regularly to maximise compliance. Measuring the animals weight and taking tape measurements of the circumference of certain areas of the body should be performed every two weeks initially. Measuring an animals weight is accurate, although does not take into consideration a change in body composition from fat to muscle and that is why a combination of weight measurement and tape measurements are ideal as tape measurements will identify when an animal has lost fat and gained muscle (remember muscle weighs more than fat).(6)
Formulated diets exist that promote both weight loss and joint health, these often contain Glucosamine and/or the essential fatty acid Omega 3. Glucosamine is also reported to be structure modifying through its ability to slow the progression of OA by altering cartilage cell metabolism. However, it is as yet unclear as to whether oral glucosamine has the ability to reach the cartilage cells. Essential fatty acids, particularly omega 3, within a dogs diet have been demonstrated to significantly improve the amount of force put through the limbs of osteoarthritic patients and this is thought to be due to its structure modifying capabilities.(10; 11)
Medical OA management involves two forms of drugs; symptom modifying drugs that relieve the pain associated with OA and structure modifying drugs that slow the progression of OA. OA is a lifelong disease and medical management should focus on relieving the constant chronic pain associated with the disease as well as managing more acute flare ups of pain. Many of the drugs available can be used for more than 28 days which allows the prescription of long-term therapy, however, it is important to maintain the lowest effective dose to allow for a higher dose to be prescribed during flare ups. An example of a structure modifying drug used in the UK is Cartrophen, although clinical trials have only reported moderate levels of comfort to be achieved by OA patients on this drug.(12; 13)
Lifestyle changes form an important part of OA management. Such changes include provision of a deep soft bed to prevent pressure sores, the use of ramps rather than stairs, the provision of rugs on hard floors to improve grip and reduce slips. The canine arthritis management website provides a wealth of knowledge on how you can modify your home to suit an arthritic dog.(6)
The major surgery performed on OA patients is total joint replacement. These surgeries are readily available for the hip, stifle and elbow joint, although have been performed in other joints. Total hip replacement is currently the most common and has been reported to achieve good to excellent results in more than 90% of cases.(14) Dogs in their early adult years experiencing pain due to OA and experiencing a reduced quality of life often undergo total hip replacement to allow the animals to lead normal active lives. Total stifle and elbow joint replacements remain salvage procedures for when all other forms of management have failed as they are technically more challenging. In cases where total joint replacement is not possible arthrodesis, the fusing of a joint, may be suitable. This relieves pain, however, results in a rigid joint that often causes compensatory wear of other structures. It is therefore best suited to low motion joints such as the carpus (wrist) or tarsus (ankle). Arthrodesis in more mobile joints, such as the shoulder, elbow and stifle are possible and can be well tolerated, however, these procedures are technically challenging and rarely performed. Arthrodesis of the hip joint is not possible and instead when total joint replacement is not possible, femoral head and neck excision can be performed. In extreme cases amputation is an option, although OA often affects several joints of several limbs and amputation of one limb may exacerbate the others.(6)
Physiotherapy in the form of hydrotherapy, electrotherapy, manual therapy and remedial exercise can massively benefit both the surgically and conservatively managed osteoarthritic patient. Hydrotherapy reduces inflammation and promotes improved joint function, muscle strength, cardiovascular fitness and endurance while exercising at a slower pace and with less force being applied to the joints. Electrotherapy in the form of LASER therapy or pulsed electromagnetic field therapy has the ability to slow the progression of OA and, along with transcutaneous electrical nerve stimulation (TENS), has the ability to relieve pain and therefore reduce the animals reliance on pain relief in drug form or improve pain relief when the animal is receiving the maximum dose of pain relieving drugs. Manual therapy, in the form of massage, stretches and joint mobilisations, not only improve the function of the affected joints but also relieve compensatory issues in other structures. An osteoarthritic patients back muscles often absorb the mainstay of compensatory force and relieving tension here can significantly improve the animals way of moving and comfort. Remedial exercise can be prescribed to maintain and in many cases improve an animals level of activity by promoting the full use of available joint motion and reducing compensatory gait abnormalities.
So that is what osteoarthritis is, what causes it and how we can manage it. My role is providing physiotherapy for these animals, however, I work with several other professions to ensure that my patients are receiving guidance in all elements of osteoarthritis management. Please get in touch if you would like me to go into any more detail on any specific elements of this blog post. I appreciate it has been a bit of a pit stop tour of osteoarthritis but I hope you have found it interesting and informative. The sources that I used are listed below.
Contact me at firstname.lastname@example.org to make suggestions on future topics.
1. King, M.R., Haussler, K.K., Kawcak, C.E., McIlwraith, C.W. and Reiser, R.F. 2013. Mechanisms of aquatic therapy and its potential use in managing equine osteoarthritis. Equine Veterinary Education, 25 (4), pp.204-209.
2. Weishaupt, M. 2008. Adaptation strategies of horses with lameness.Veterinary Clinics of North America: Equine Practice, 21, pp.79-100.
3. Astephen, J.L., Deluzio, K.J., Caldwell, G.E., Dunbar, M.J. and Hubley-Kozey, C.L. 2008. Gait and neuromuscular pattern changes are associated with differences in knee osteoarthritis severity levels. Journal of Biomechanics, 41, pp.868-876.
4. Herzog, W. and Longino, D. 2007. The role of muscles in joint degeneration and osteoarthritis. Journal of Biomechanics, 40, pp.54-63.
5. Edge-Hughes, L. and Nicholson, H. 2007. Canine Treatment and Rehabilitation. In: pp.207-237. McGowan, C., Goff, L. and Stubbs, N. eds. Animal Physiotherapy: Assessment, Treatment and Rehabilitation of Animals.Oxford: Blackwell Publishing. pp.207-237.
6. Pettitt, R.A. and German, A.J. 2015. Investigation and management of canine osteoarthritis. In Practice, 37 (1), pp.1-8.
7. Mlacnik, E., Bockstahler, B.A., Müller, M., Tetrick, M.A., Nap, R.C. and Zentek, J. 2006. Effects of caloric restriction and a moderate or intense physiotherapy program for treatment of lameness in overweight dogs with osteoarthritis. Journal of the American Veterinary Medical Association, 229 (11), pp.1756-1760.
8. Marshall, W.G., Hazewinkel, H.A., Mullen, D., De Meyer, G., Baert, K. and Carmichael, S. 2010. The effect of weight loss on lameness in obese dogs with osteoarthritis. Veterinary research communications, 34 (3), pp.241-253.
9. Deagle, G., Holden, S.L., Biourge, V., Serisier, S.L. and German, A.J. 2015. the Kinetics Of Weight Loss In Obese Client-owned Dogs. Journal of Veterinary Internal Medicine, 29 (1), pp.443-444.
10. Fritsch, D.A., Allen, T.A., Dodd, C.E., Jewell, D.E., Sixby, K.A., Leventhal, P.S., Brejda, J. and Hahn, K.A. 2010. A multicenter study of the effect of dietary supplementation with fish oil omega-3 fatty acids on carprofen dosage in dogs with osteoarthritis. Journal of the American Veterinary Medical Association, 236 (5), pp.535-539.
11. Roush, J.K., Cross, A.R., Renberg, W.C., Dodd, C.E., Sixby, K.A., Fritsch, D.A., Allen, T.A., Jewell, D.E., Richardson, D.C., Leventhal, P.S. and Hahn, K.A. 2010. Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis. Journal of the American Veterinary Medical Association, 236(1), pp.67-73.
12. Aragon, C.L., Hofmeister, E.H. and Budsberg, S.C. 2007. Systematic review of clinical trials of treatments for osteoarthritis in dogs. Journal of the American Veterinary Medical Association, 230 (4), pp.514-521.
13. Sandersoln, R.O., Beata, C., Flipo, R.M., Genevois, J.P., Macias, C., Tacke, S., Vezzoni, A. and Innes, J.F. 2009. Systematic review of the management of canine osteoarthritis. Veterinary Record, 164(14), pp.418-424.
14. Allen, M.J. 2012. Advances in total joint replacement in small animals. Journal of Small Animal Practice, 53 (9), pp.495-506.