Osteoarthritis (arthritis) is a well-recognised condition in people and dogs. It is a common cause of chronic pain, where 1 in every 5 adults is affected. The incidence of this disease is similar to that in dogs, where approximately 20% or more of the dog population are affected. In most cases, osteoarthritis arises from joint damage due to repetitive movement (‘wear and tear’), however, it can also begin as a result of an injury. Either way, it is a progressive disorder of moveable joints, characterised by loss of articular cartilage, production of new bone at articular margins and changes in joint membrane.
Basically, cartilage covers the ends of bones, and together with joint fluid, acts as a shock absorber and provides an almost frictionless, weight-bearing surface. As cartilage breaks down, bones at the articular margins thicken, and gradually rub against each other, causing pain. Furthermore, damaged joint tissue also releases inflammatory mediators which can exacerbate the pain and swelling of the joint.
Although this disease can occur at any age, it is commonly found in middle-aged to geriatric dogs, with no reported bias for male or female. Large and giant breed dogs have a genetic predisposition for developmental orthopaedic diseases, which may progress to osteoarthritis at later stages. Obesity and excessive, high-impact exercise can also increase stress on the joints and result in erosion and degeneration of cartilage.
Osteoarthritis develops over time, and owners might not notice the gradual and subtle changes in behaviour or movement. Many clinical signs of this disease are considered ‘normal’ age-related changes, and are not necessarily an indicator that their pet is in pain or needs veterinary treatment. Some of the classic signs of osteoarthritis include:
- Stiff gait, difficulty getting up and moving around
- Slowing down, reluctance to walk
- Licking or chewing at particular joints
- Depressed, irritable, growling or acting defensively when touched
Diagnosis of osteoarthritis begins with a detailed history. Numerous contributing factors have been reported and include age, breed size, breed inherited traits (e.g. hip dysplasia, elbow dysplasia), stress activity (e.g. excessive athletic activities), body weight, and previous joint injuries or trauma. This is followed by a thorough physical and orthopaedic examination, where gait and joint function are assessed. Typically, affected pets present with limping, reduced range of movement or pain on joint manipulation. Joint swelling or thickening and crepitus can often be detected too. Further investigation with imaging modalities are often employed, and include radiography, MRI and arthroscopy. Studies have reported poor sensitivity of radiography in determining the severity of osteoarthritis, as they are used mainly to demonstrate bony changes and do not identify lesions in the cartilage or joint membranes. Radiographic findings in animals with osteoarthritis include bone remodelling in joint spaces, narrowing of joint spaces, and soft tissue swelling around the joint. However, radiographic changes can be subtle even in animals with marked disease. The latter two techniques, MRI and arthroscopy, provide better assessment and categorisation of cartilage disease.
A multi-pronged approach to this disease is warranted, and encompasses medical treatment, dietary management, weight control, exercise, physiotherapy and alternative therapies.
1) Medical treatment
The use of non-steroidal anti-inflammatory drugs has been the mainstay of management for osteoarthritis, and is directed at alleviation of pain and discomfort. Other types of analgesics are sometimes used in conjunction with this class of drugs due to the complex neurobiology of pain. Moreover, a multimodal pharmacological approach allows for lower doses of each drug to be used to avoid potential side effects.
2) Dietary management
Dietary measures can help reduce or eliminate the need for drugs. In addition to providing the building blocks for cartilage repair, specific nutrients can modulate the inflammatory response and protect against oxidative damage. A variety of nutrients, including long chain omega-3 fatty acids (EPA and DHA found in fish oil), chondroitin sulfate, glucosamine hydrochloride, antioxidants and green-lipped mussel powder, have proven beneficial for the management of osteoarthritis. It is possible that all these nutrients act synergistically to reduce inflammation and pain, limit further cartilage degeneration, and support the regeneration of damaged cartilage and joint fluid. All dietary interventions usually take a period of time to be effective.
3) Weight control and exercise
Perhaps the most crucial aspect in the therapy of osteoarthritis is weight management and controlled physical exercise. Excessive bodyweight places increased mechanical stress on the joints, thus it is important to maintain a lean frame and control obesity. The pet’s exercise routine should also be modified to suit the severity of the disease. Short bouts of low impact exercise, such as lead walking or swimming, are beneficial to provide positive physiotherapy and improve well-being by releasing endorphins (which can have an anti-inflammatory effect). High-intensity activities should be avoided as it can accelerate the progression of osteoarthritis.
4) Physiotherapy and alternative therapies
As clinical signs of osteoarthritis progress, dogs will tend to move less due to pain and stiffness. This inactivity results in reduced joint flexibility and muscular atrophy. Physiotherapy is targeted at slowing down these changes. It is defined as a therapy using physical means such as movement (mobilisation, stretching, exercise, massage), thermal agents (cold, heat), electric current, sound waves, light, magnetic fields, extra-corporeal shock waves, etc. The benefits of these techniques stem from improving blood circulation, resolving inflammation and pain, preventing tissue retraction and adhesions, strengthening muscle, and improving motor function.
Aquatic therapy is a form of active exercise and was developed to help reduce the amount of weight the pet bears during activity. The amount of weight bearing is adjusted by varying the depth of water in which the pet is placed. Swimming promotes the use of all limbs and enhances cardiovascular endurance.
Acupuncture is another form of alternative therapy, and can be used solely or as an adjunct therapy. According to traditional Chinese medicine, osteoarthritis corresponds to a slowing down in the circulation of vital Energy (Qi) in the meridians surrounding the joints. Stimulation of specific acupoints can regulate organ function and provide analgesic effect.
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This article is written by Dr. Sheryl Ng, a practising vet in Singapore. Dr Sheryl graduated from the University of Sydney and joined the veterinary ranks in Singapore shortly after. She loves both large and small animals, and has a special interest in the small furry exotic animals. She also completed a basic pet grooming course in Singapore, and believes in holistic therapy – keeping your pet clean and tidy is just as important in ensuring a healthy and happy companion. Dr. Ng shares her life with an easily excitable cocker spaniel, a timid and sweet Cavalier, and a Yorkshire Terrier. The Yorkie rules the family.