Osteoarthritis (OA) is the most common form of arthritis in dogs, affecting approximately a quarter of the population. It is a chronic joint disease characterized by loss of joint cartilage, thickening of the joint capsule and new bone formation around the joint (osteophytosis) and ultimately leading to pain and limb dysfunction. Majority of OA in dog occur secondarily to developmental orthopedic disease, such as cranial cruciate ligament disease, hip dysplasia, elbow dysplasia, OCD, patella(knee cap) dislocation. In a small subset of dogs, OA occurs with no obvious primary causes and can be related to genetic and age. Other contributing factors to OA include bodyweight, obesity, gender, exercise, and diet.
Signs of OA are often times non-specific and include:
- Activity impairment: reluctance to exercise, decrease in overall activity, stiffness, lameness, inability to jump, changes in gait such as ‘bunny-hopping.’
- Pain on manipulation: behavioral changes such as aggression or signs of discomfort.
Diagnosis of OA is usually made by a combination of history, physical exam and various imaging modalities.
- Initially, a physical exam will orient towards the affected joint or joints. The veterinarian will palpate the limbs and joints to assess for painful response, thickening of the joint capsule, accumulation of joint fluid (effusion) or sometimes osteophytes and muscle atrophy (wasting).
- The most common imaging modality used is X-ray. These are of limited use though, because they only give information on bone structural changes (osteophytosis) and show only limited soft tissue changes, therefore, should be combined with physical exam findings.
- Other diagnostic tools becoming more popular include magnetic resonance imaging (MRI) which can provide information regarding soft tissue structures (ligaments, menisci) and computed tomography (CT) that is good for assessing bone structural changes in joints with more complex anatomy such as elbows, carpi (wrists) or tarsi (ankles).
The conservative approach can slow down the progression of the disease, and many dogs can live comfortably for years following diagnosis. However, OA is a progressive disease and will continue to worsen with time. If surgery is performed the recovery of those dogs is usually very good especially with total joint replacement surgery as the diseased joint is completely removed and replaced.