Nonsurgical management of osteoarthritis and pain (Proceedings)
Degenerative joint disease (DJD) or osteoarthritis (OA) is typically a progressive disorder that affects diarthrodial joints. It has been defined as "an inherently noninflammatory disorder of movable joints characterized by deterioration of articular cartilage and by the formation of new bone at the joint surfaces and margins". Osteoarthritis can develop from instability, chronic inflammation, incongruity or disease process that creates cellular pathology in the joint. In the dog, OA is usually associated with an inciting cause such as elbow or hip dysplasia. With these and other diseases that cause OA in the dog, OA begins with a disruption of the surface layer of the articular cartilage, and this physical damage initiates biochemical alterations that result in degradation of joint tissues. While arthritis is not an inflammatory based disease, the clinical symptoms associated with arthritis certainly can be associated with inflammation of the periarticular tissues. Prior to instituting treatment a definitive diagnosis must be made, beginning with the patient signalment. Osteoarthritis can affect dogs of any age but as age increases, intuitively the probability of OA developing and causing clinical signs increases. Owners might report that their dog tires easy when attempting to exercise, is reluctant to use stairs or jump, has a lameness or pain in the morning or after exercise, or has a change in behavior. The clinical signs may wax and wan over a period of days or weeks. On physical exam the diagnosis can be made by finding muscle atrophy, localizing pain to a joint(s), determining that a joint has a decreased range of motion, or finding an increase in joint size from periarticular fibrosis or osteophytosis. Plane or stress radiographs and arthrocentesis can confirm impressions from the clinical exam. However, it is critical to make a diagnosis of joint pain during the clinical exam and to confirm that OA is present and related to the pain with the assistance of radiographs. Although most would agree that the radiographic presence of OA increases the probability that a dog will have associated joint pain as stated before it is important to understand that the radiographic presence of OA, by itself, does not necessarily imply that a patient will have clinical signs of disease. It has been demonstrated in several reports that the relationship between the radiographic presence of OA and clinical symptoms is poor.3,4 In effect, radiographs are an excellent way to diagnose the presence of osteophytes and confirm a physical exam finding but are a poor indicator of the health status of the cartilage and/or the presence of inflammation.
The treatment of OA is either nonsurgical or surgical. Nonsurgical treatment should almost always be tried first and in many cases will be successful. For example, for the treatment of canine hip dysplasia, it was recently reported that all clinical symptoms resolved in approximately 50% of dogs treated nonsurgically. While OA is a slowly progressive disease there are undoubtedly inflammatory flares that can be managed medically. Nonsurgical management should focus on treatments where science provides evidence of efficacy. Many owners have limited financial resources so advice should be made to optimize those resources. First, dietary food intake restriction has been demonstrated to slow the onset and progression of OA in dogs with hip dysplasia.6 In that study, Labrador Retrievers that were fed 25% less food than what there litter mate day the previous day developed radiographic and clinical evidence of hip dysplasia later in life.6 I would suggest that in dogs are belong to a breed that is predisposed to orthopedic disease(s) or if they have a disease that will likely lead to OA (e.g. rupture of the cranial cruciate ligament, fragmented coronoid process, hip dysplasia) should be maintained at a body condition score of 4-5. If the dog is over weight, weight loss as a sole treatment has been demonstrated to provide significant relief and improve limb function in dogs with joint pain from OA. Daily activities like leash walks should be encouraged. Consistent, low load use of the limbs will not only provide the joint the range of motion which is needed to improve cartilage and synovial lining health but it will also assist in the management of the patient's body weight and begin the reverse disuse muscle atrophy that had developed. Swimming can also be very helpful. Specifically, aquatic therapy provides buoyancy (which eliminates ground reaction forces), multiplanar resistance to the muscles, and when dogs swim they use their joints with more flexion than during land based activities.8 Although it may be important for the patient to have exercise restriction this should be limited to when the joint is very painful during the early phases of treatment. In general, exercise restriction should also be limited to only a few days to a week and when the patient is "having a bad day".