Degrative joint disease (DJD) or osteoarthritis (OA)is a common cause of lameness in horses of all disciplines. In performance horses it often affects high motion joints such as the carpus and the fetlock joint. In pleasure horses it tends to affect more low motion joints such as the hock. It is a disease process that once started is irreversible and requires management to maintain the joint in a comfortable condition.
The joint is made up of a number of structures: The articulating bone surfaces, a cartilage layer, a joint capsule, the synovium (which consists of the synovial fluid and membrane), and the ligamentous supporting structures. The majority of the nerve endings are within the fibrous capsule and the supporting ligaments; there are very little in the articular cartilage and synovium. The pain that is associated with degrative joint disease is a result of joint effusion (increased fluid in the joint), fibrosis or scarring of the joint capsule and inflammation.
There are many potential causes of DJD including long term loading of the joint (many miles on the horse), injury to the joint such as fractures or bone chips or a previous joint infection. All of these things can get the ball rolling on this progressive disease process. This is not a disease process that is limited to older horse either – many younger horses, especially which are very active from a young age such as race horses or high-performance quarter horses can also show signs of degrative joint disease.
Regardless of the age or discipline of your horse, early recognition of the clinical symptoms is important for the on-going management of the joint. Clinical symptoms that we frequently see include; stiffness, lameness, gait changes or a reduced performance, joint filling (“effusion”), reduced motion of the joint and heat in the joint.
Common radiographic changes that we identify include narrowing of the joint spaces, bone degeneration and / or formation of “spurs”.
There are a number of potential treatment options for horses with degrative joint disease; which one is selected may be influenced by the severity or progression of the degeneration. The underlying aim of treatment involves reduction of the inflammation and reduction of load / increase support of the joint. Medications can be administered orally, into the vein or muscle or directly into the joint itself.
Common systemic treatment options include oral or IV anti-inflammatories – the most common one being phenylbutazone. Joint supplements may be effective in some cases. Examples of these are e 4-Cyte, Adequan or Pentosan.
Local therapies are those that are injected directly into the joint. Typically, a combination of corticosteroid and hyaluronic acid are used. The corticosteroid is effective at decreasing inflammation and Hyaluronan helps to lubricate the joint. Although adverse effects have been attributed to intra-articular corticosteroids, more recent studies have demonstrated a beneficial effect. In these models of osteoarthritis, intra-articular corticosteroids have shown to decrease inflammation, increase hyaluronante and proteoglycan synthesis as well as slow the progression of osteoarthritis.
In the more recent years more protective intra-articular medications have gained popularity. These include IRAP which you can read more information about in the information hand out about “biological medications”.
Environmental and husbandry changes can be extremely beneficial to your horses’ overall comfort. Things that can be managed at home include diet, exercise, and foot care.
Diet: a controlled and balanced diet plays a very important role. Overweight horses will have an increased pressure on their joints thus reduction of weight or maintenance of a healthy weight is recommended.
Exercise: not only does exercise help to keep your horses’ weight under control but it is also important to help maintain range of motion in the joint. The amount and type of exercise that your horse should be doing can be discussed with your veterinarian.
Foot care: There is an old saying “no foot no horse”. Keeping your horses’ feet well trimmed and balanced will help to decrease the stress and load on the joints. Occasionally special “therapeutic” shoeing will be recommended.
Degenerative joint disease does not necessarily equate to the end of your horses career. Early recognition of clinical symptoms and working closely with your veterinarian is central in the ongoing management of your horses comfort and athleticism.
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