Kirsten Voigt, DVM

With the riding season in full swing, many owners may start noticing that their show horse isn’t extending the way he used to, or their trail horse looses steam and stumbles which is uncommon for her.  With use and age it is very common for horses to develop arthritis.  Initial signs are often subtle but with time become glaringly obvious.  Arthritis (or the more specific term osteoarthritis) has plagued horses and owners for years.  The good news is that there is continual research on the subject which gives us a better understanding of the disease.  With a better understanding comes better solutions.   

Osteoathritis (OA) is one of the most common causes of lameness in the horse.  Also known as degenerative joint disease (DJD), it is a condition that can be caused by acute injury, secondary to a different joint issue, or more commonly, by low-grade repetitive trauma from riding and training.  When a joint is used, there is a cycle of degradation, and possibly damage, followed by regeneration and repair.  The joint remains healthy as long as the degradation does not exceed the ability to repair.  Often the balance is tipped by hard and heavy use or just many years of use.  This leads to inflammation of the joint capsule that stabilizes the joint and the synovial lining that produces the joint fluid. The effect is instability and unhealthy joint fluid. 

The cartilage that protects the ends of the bone is responsible for shock absorption and allowing the bones to glide over one another without resistance or pain.  It is highly dependent on stability, to minimize damage, and healthy joint fluid, to encourage repair.  Once the inflammation starts, damage can occur to the cartilage as well.  With inflammation and cartilage damage comes the pain and a decreased range of motion that negatively affects performance. 

The body responds by laying down extra bone in and around the joint in an attempt to stabilize the joint. Unfortunately the effect is a build up of irregular bone that interferes with movement, causes pain and is more easily fractured than normal bone.  These boney changes can be seen on x-rays but are only there after the problem has been going on long enough for this response to take place.

There is a wide range of the disease condition.  Initial signs are reduced range of motion, shorter stride length, stumbling, and fatiguing more quickly.  As the disease progresses an obvious lameness or limp develops, the joint may be swollen or puffy and feel warm after exercise.  In severe cases you may see changes in hoof shape or muscling in the affected leg due to lack of use even when standing (less commonly if both right and left legs are affected to the same degree).  The joint(s) may get a knobby appearance from the abnormal bone formation and the horse may have great difficulty laying down and standing back up.

The first step in addressing OA is to have the horse evaluated.  A lameness exam can be used to determine where the OA is, which can be challenging at times with four legs involving over 30 joints not to mention the spine.  Techniques that are used are flexion tests where the joint is bent for a given amount of time before trotting or blocks where areas are numbed to pinpoint the source of pain.  X-rays can then be taken of the joint in question.  The amount of change seen on x-rays can help determine how chronic the problem is and what therapy would be best.

The hard part at this point is deciding what treatment or combination of treatments is best.  This is because there are so many options out there with so many companies making claims that may or may not be validated.   We’ll discuss some of the possible treatments, and the drugs or supplements mentioned are those whose companies have made efforts to provide some legitimate proof that they work by performing research and testing on their product.

Specific joint therapies include topical anti-inflammatories (Surpass) to reduce pain and inflammation, joint injections with anti-inflammatory medications (steroids) to break the inflammation cycle or joint injections with drugs that support joint fluid health in order to reduce inflammation (Legend) or heal cartilage damage (Adequan).  Both Legend and Adequan can also be given as a shot other than in the joint.  They are effective on all joints in this way but not as potent as putting it directly into the joint.  An ounce of preventions can simply be to include cold hosing or icing after workouts which can significantly reduce the inflammation.

More general treatments include oral Bute which is like taking a Tylenol or the newly released Equioxx.  Both of these reduce pain and inflammation to the same degree but Equioxx is developed to eliminate the stomach and kidney side effects that are associated with the prolonged use of Bute.  Other oral therapies involve the nutraceuticals which are oral supplements such as Cosequin and Cortaflex.  Because nutraceuticals are not drugs they are highly unregulated making it a guessing game to know what is a waste of money and what is helpful.  Stick with the reputable companies and those that have some proof of research such as the two mentioned above.  Others may ride on their coat tails and claim they are the same but without proof, it’s just talk.

In most cases exercise and use is helpful when done at an appropriate level.  Movement helps stimulate blood flow and maintain range of motion.  I encourage people to continue riding as many years as the horse is comfortable doing so.  Being a pasture ornament isn’t such a bad life either but there may come a time in severe cases where quality of life needs to be taken into consideration.  When there are more bad days than good days or if they continue to get stuck laying down and therapies are no longer working, it may be time to end the pain

It is possible to use several treatments at the same time if needed.  Given all the options and combinations it is important to work with your veterinarian to come up with the right regime for your horse.  The important thing to remember is that prevention is always best, but when a problem arises, the earlier treatment is started, the more effective it is and the better the outcome.  The solution is early intervention to prevent the chronic inflammation that leads to irreversible bony changes and permanent arthritis.  Even mild lameness or reduced performance should be addressed early on to minimize damage.