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 serious 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 pharmacological 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, conformation of the breed, genetics, molecular or metabolic factors. Once the degenerative joint disease begins, a series of biochemical, 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 inflammatory 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 associated with OA affect the cartilage, subchondral bone, and the surrounding joint capsule which becomes inflamed, thickened, 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 worsens 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 cannot 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 orthopedic 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 progression and the more effective the treatment will be for most patients.
Osteoarthritis Pain Checklist – these symptoms warrant a veterinary evaluation of your pet for OA
Changes in activity:
[ ] Difficulty rising from a resting position
[ ] Difficulty getting into a resting position (lying down or sitting)
[ ] Lying down or spending more time resting more than usual
[ ] Stiffness and lameness after exercise
[ ] Reluctance to go for their usual walks or runs (or preferring shorter walks)
[ ] Trouble getting up or down from a bed or sofa
[ ] Problems getting into, or out of, a car
[ ] Trouble climbing stairs (or simply slower on stairs than usual)
[ ] Limping or favoring a leg or stiffness in one leg
[ ] Difficulty walking, running or jumping normally
[ ] Change in posture such as a hunched or arched back, drooping back end, stiff neck
Changes in behavior (may be subtle at first):
[ ] Uncharacteristic hiding or being less social in general
[ ] Decreased appetite or less or interest in food
[ ] Hesitant around other pets or children
[ ] Loss of interest in play (with people or other pets)
[ ] Unusual barking or other vocalization (whining, groaning)
[ ] Aggressive or defensive reactions to touch or to other pets (twitching skin, grumpiness)
[ ] Avoiding being petted or brushed over certain areas
[ ] No longer greeting people enthusiastically
[ ] Difficulty getting in position to defecate
[ ] For male dogs – squatting to urinate, rather than lifting his leg
[ ] For female dogs – shaking while she squats to urinate or defecate
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, rehabilitation 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.
Elizabeth F. Baird, DVM, CVPP, CCRT, CVMA
Country Oaks Animal Hospital & Kennel
Steele Pain Management & Rehabilitation Center