Degenerative Arthritis in Dogs
In-depth Information on Diagnosis
Diagnostic tests are needed to recognize DJD and exclude other diseases. Tests may include:
Orthopedic examination. A thorough orthopedic examination to reveal the presence of joint pain, swelling and tenderness. A careful history will also tip the veterinarian’s suspicion toward a specific primary disease process. A ten-month-old Labrador with difficulty rising in the rear legs has to be looked at as a prime candidate for canine hip dysplasia. Obviously there are other differential diagnoses, but many are more common in particular ages and dog breeds.
Radiographs. X-rays are usually an essential diagnostic tool. Since the majority of DJD seen in small animals is secondary to some congenital or acquired event, radiographic diagnosis of this inciting cause is important. With OCD of the shoulder a characteristic “bony defect” in the proximal humerus is detected. With FCP variable amounts of bone production are evident over the bones making up the elbow joint. Free fragments and bony changes are present. With UAP, the anconeal process has not developed properly and fused to the ulna. Canine hip dysplasia initially occurs at less than a year of age with evidence of looseness or laxity of the hips. The femoral head does not ride within in the bone socket of the pelvis (acetabulum). As CHD progresses, large amounts of free bone and loss of articular (joint) cartilage destroy the normal hip architecture. When dogs with CCL rupture in the knee or hock, problems such as joint swelling and bony production may occur.
Contrast studies. Usually the diagnosis of DJD is fairly straightforward, but sometimes, additional views or “stress” views may be necessary. Injecting contrast (dye) into the joint and obtaining a radiograph is seldom necessary. Also, advanced imaging techniques such as CT and MRI are seldom necessary. Bone scans involve injecting a small amount of a radioactive material in the body that would normally accumulate in bone. When a camera is used to record the nucleotide at the joints, an area of increased accumulation may help the clinician detect a subtle area of lameness.
Force plate. Although used primarily as a research tool to assess a degree of lameness and response to various treatment modalities, the force plate can be used in the clinical setting to help evaluate the degree of lameness. A plate or mat is placed on the floor and the dog is allowed to make numerous passages across the plate. Sensors in the plate are attached to a computer that analyzes the force each step makes on the plate. There are a number of variables that can occur, but force plate analysis can be helpful.
Aspiration of joint fluid. Degenerative joint disease is just one of many types of joint disease that can occur. The other large category of joint diseases is termed “inflammatory.” With these diseases, a large amount of white blood cells are attracted to the joint from various disease processes. The most common of these are “autoimmune” diseases where the body recognizes certain portions of an individual’s joint to be foreign or abnormal and tries to destroy it. Canine rheumatoid arthritis is an example of this type of arthritis. This type of arthritis is uncommon when compared to DJD. Aspiration of joint fluid can be helpful in determining is the arthritic process is inflammatory (rheumatoid like) or non-inflammatory (DJD).
In-depth Information on Treatment
Medical therapy, exercise restriction and loss of excess weight are the hallmarks to medical treatment. Treatment for DJD may include one or more of the following:
Nonsteroidal anti-inflammatory drugs (NSAIDs). These drugs primarily inhibit inflammation activity. In particular, NSAIDs they inhibit the synthesis of prostaglandins. While this is good, there is also a major side effect. In the stomach, prostaglandin helps protect the stomach lining from the normal stomach acids. People and animals on some of the early NSAIDs (aspirin, phenylbutazone and ibuprofen) experienced variable gastrointestinal side effects. Deracoxib (Deramaxx®), carprofen (Rimadyl®), meloxicam Mobic® or Metacam®), Tepoxalin(Zubrin®) and etodolac (Etogesic®) are cyclooxygenase 2 (COX2) inhibitors that specifically act against the pathway directed at the joints but selectively leaves the pathway to protect the stomach (COX1) intact. Although these drugs alone can produce idiosyncratic side effects, they appear to be superior over earlier NSAIDs.
Osteoarthritis agents. This slow acting class of drugs help to modulate the progression of DJD. Many of the oral varieties are not regulated by the FDA and fit in the classification of nutraceuticals (vs. pharmaceuticals). The majority of these supplements contain glucosamine and chondroitin sulfate (remember, these are the main chemical substances making up the cartilage matrix). Cosequin contains purified glucosamine, condroitin sulfate and manganese ascorbate. It is hypothesized that, with DJD, the demand for cartilage precursors or building blocks is greater than the body’s ability to make them. This results in a diminished repair capacity. This is only theory and no hard scientific evidence illustrates the cartilage cells are nutritionally deprived. A number of studies have shown that these compounds do incorporate in healing cartilage and anecdotal reports are favorable. Many times these compounds are used in conjunction with NSAIDs.
Dietary therapy with diets such as Hill’s® Science Diet® j/d™ or Purina® JM Joint Mobility™ brands may be beneficial in some dogs. These diets are formulated with Omega-3 fatty acids, glucosamine, and chondroitin sulfate and help to maintain weight, reduce pain and improve mobility in dogs with osteoarthritis. It is also extremely beneficial for dogs with joint disease to maintain an ideal body weight.
Surgical treatment of end stage DJD results in either removal of one side of a joint and allowing a “false joint” to form. Since there is no longer any rubbing of the joint surface, much of the pain is eliminated. This classically was done for hip dysplasia (femoral head ostectomy). Obviously the joint has been de-stabilized, but many smaller animals can accommodate very well.
In larger breeds of dogs, prosthetic replacement has a much more predictable outcome. Total hip replacement has been successfully performed for 30 years in the dog.
In other joints, surgical fusion of a joint might be helpful. By eliminating the joint surfaces and allowing the joint to fuse in a functional, anatomic position, many dogs can have a pain-free existence with adequate mobility.