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).
Treatment recommendations for OA are multimodal which means they include different approaches and can be either conservative, surgical or a combination of both. All treatment decisions are made based on individual patients and in discussion with the animal owner and surgeon.
- Weight control is by far the most critical aspect of OA management. Fat produces inflammatory mediators that perpetuate the inflammation process and increased body weight put additional force on the joints, causing pronounced OA changes and can ultimately be painful with limited mobility. In an ideal body weight, you should be able to: 1) feel your dog’s ribs but not see them; 2) see an hour-glass figure when viewed from above; 3) see a tucked up belly when viewed from the side.
- Activity modification: High-impact activities such as running or jumping should be limited as they can cause more inflammation and pain. These activities should be replaced with more controlled activity like leash walks. Low impact consistent exercise is good to help build the muscles around the joints and will eventually promote joint stability.
- Rehabilitation: Animal rehabilitation such as range of motion exercises, therapeutic exercises, and aqua therapy (underwater treadmill, swimming) help to improve joint mobility, increase muscle mass, and improve exercise endurance. Acupuncture, LASER therapy, and other rehabilitation modalities are commonly recommended although there is an overall lack of studies to prove its benefit.
- Pain control: Nonsteroidal anti-inflammatory drugs (carprofen, meloxicam, deracoxib, ketoprofen, etc.) are the most commonly used medication for OA pain control. In patients that cannot tolerate nonsteroidal anti-inflammatory drugs, adjunctive pain medications (amantadine, gabapentin, tramadol, codeine, corticosteroids, acetaminophen, acupuncture) can be considered, although there is an overall lack of studies supporting their efficacy for OA pain management.
- Joint supplements: The exact mechanism of how joint supplements may help alleviate OA pain is not well understood. Chondroitin sulfate, glucosamine sulfate, omega-3-fatty-acid supplementation are the most commonly recommended joint supplements and does not have severe adverse effects.
- Disease modulating agents: This can be given either as a muscle injection (PSGAG) or injection within the joint (corticosteroids, platelet-rich plasma, hyaluronic acid, and stem cell). More research is necessary to ascertain the benefit of disease-modulating agents.
- Surgical management can be indicated and in some instances are the best treatment choice. The surgeries that would be performed are either treatment of the primary cause, such as suture-based or osteotomy-based techniques for knee cranial cruciate ligament rupture, or salvage procedure to remove the painful joint components, such as femoral head and neck excision (FHNE), arthrodesis (fusion of joints), total joint replacement surgery (most commonly in hips, stifles, elbows)