Canine Osteoarthritis: A Vicious Cycle of Inflammation and Pain.
–by Dr. Elizabeth F. Baird, DVM, CVPP, CCRT, CVMA
Canine arthritis, or more correctly, osteoarthritis, is a progressive, destructive, and debilitating disease that affects at least 20% of dogs over the age of one. It has an immensely negative impact on quality of life in our pet population. It is also known as Degenerative Joint Disease (DJD) or degenerative arthritis. OA is the most seri- ous cause of disability in geriatric dogs, and, all too often, the chronic pain and debilitation of OA can lead to euthanasia. The symptoms of OA can be subtle,
so knowing how dogs express discomfort and pain is important in recognizing the problem. Treatment involves approaching the problem from multiple angles, known as multi-modal therapy, to maximize success and to reduce the risk of adverse reactions or side effects from reliance only on pharmaceutical medications. Treatment strategies, including phar-
macological and non-pharmacological protocols, will be addressed in Part II of this series. Preventive measures will also be discussed in Part II.* There are multiple causes for
osteoarthritis but they all follow a similar path. It may begin with an injury, a joint instability such as hip dysplasia, conforma- tion of the breed, genetics, molecular or metabolic factors. Once the degenerative joint disease begins, a series of biochemi- cal, molecular, and biomechanical changes occur in the cells at the site of the injury affecting the cartilage matrix of the joint. For example, there is evidence that inflam- matory and chemical changes appear in the knee of an affected animal as soon as 24 hours after a dog ruptures an anterior cruciate ligament, a common injury in large breed dogs. Cartilage has very little ability to heal
itself and the inflammatory changes associ- ated with OA affect the cartilage, sub- chondral bone, and the surrounding joint capsule which becomes inflamed, thick-
68 THE NEW BARKER Jackson, photographed at Woofstock, Tampa.
ened, and contracts – causing stiffness in the joint. These changes inevitably lead to painful degradation of the cartilage that protects the bone beneath and ultimately varying degrees of inflammation, joint pain, tenderness, and loss of joint mobility. Once an area becomes painful, the pet then tends to favor that area and use it less which then leads to muscle atrophy and further loss of strength in the affected region. OA can be mild, moderate, or severe
when it is first identified, but it is always progressive. The speed with which it wors- ens will vary according to the cause of the osteoarthritis and the individual factors such as lifestyle, age and breed. The destructive impact on quality of life can- not be understated – the chronic pain of OA is a leading cause of euthanasia in our older pets. The first step to a diagnosis of OA is
often a pet owner observing changes in their pet’s behavior and bringing that information to their veterinarian. An orthopedic evaluation by the doctor can usually clarify if joint pain exists and which joints are impacted. Changes occur at a cellular level long before anything
abnormal can be revealed on x-ray, so the orthopedic examination is truly the first step of a diagnosis before radiographs are required. Radiographs (x-rays) can then help clarify the severity of the bone remodeling based on the visible changes observed as well as rule out other ortho- pedic problems such as bone infection or tumor that can cause similar symptoms. Dogs, by their very nature, do not
demonstrate pain in the same ways as humans. When dogs express pain, it is often by relatively subtle changes in behavior. Also, the chronic pain of OA is very different from acute pain such as that exhibited with a broken bone, where the dog will typically demonstrate obvious signs of pain. Chronic pain is often harder to detect and may often be mistaken for simple aging changes and the slowing down experienced over time. In fact, this “slowing down” is often due to OA, not age. The earlier OA is identified, the greater the chance for slowing its progres- sion and the more effective the treatment will be for most patients. Once osteoarthritis is diagnosed,
there are a variety of treatment options based on the individual situation including the severity of discomfort. These may vary from simple environmental changes and oral nutritional supplements in the early stages, to prescriptive medications, rehabil- itation therapy, and regenerative medicine such as stem cell therapy for the more severely affected dogs. Part II of this series will review treatment options in detail as well as useful preventive measures to help delay or prevent the onset of osteoarthritis.
*Part II of this series will review treatment options in detail as well as useful preventive measures to help delay or prevent the onset of osteoarthritis. It will appear on The New Barker blog at
www.TheNewBarker.dog on 01/15/17.
www.TheNewBarker.com
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