02/28/2026
Degenerative joint disease (DJD), commonly known as osteoarthritis, is a condition where the cartilage in joints wears down over time, leading to pain, stiffness, and reduced mobility.
This happens in humans (ask me how I know) and horses, regardless of level of performance. Upper level competitors are more likely to have career-ending types of problems than horses that get ridden on trails only occasionally, but even unbroke/unridden horses are plenty capable of injuring themselves in the pasture or even in the stall.
Regardless of the level of athletic involvement, dealing with horses often involves managing chronic orthopedic conditions to maintain overall health.
Identifying DJD early would obviously be ideal, but that can be challenging. Biomechanical problems can begin early in life secondary to angular or rotational limb anomalies (carpal or fetlock valgus/varus, improper hoof balance, etc). These will cause uneven stresses on joints and supporting structures that compound over time, so that a horse with even a mild amount of toe-out conformation has an increased likelihood of DJD in the coffin or pastern joints. These uneven forces limit the “lifespan” of the joint, so that if the same joint in a horse with normal conformation has a limit of “X” number of cycles through its range of motion, the toed out horse has less than X number of cycles, and the sooner we hit that limit, the faster the joint will show signs of DJD. A young Thoroughbred at the track will go through more cycles of motion in a month than an unridden horse in a pasture will go through in years.
It’s not unusual for DJD to appear to develop suddenly, particularly in stoic horses that love their jobs. But it’s most commonly been developing for years, and finally gets to the point that the horse can’t ignore it any longer.
The first step in diagnosing DJD is confirming where the problem is located. Diagnostic regional anesthesia (nerve blocks) are usually the first tools used to localize the source of lameness.
Once the source of the issue is confirmed, imaging is used to specify and characterize it. X-rays are usually the first modality used, but if no abnormalities are noted, we can ultrasound the area to try to get to the bottom of the problem. One wrinkle we can run into is the fact that some horses have abnormalities on x-rays that have nothing to do with the lameness, and some really lame horses can have pristine x-rays (giving rise to one of my favorite sayings – “you don’t ride the x-rays”).
X-rays only show lesions in bones, ultrasound only shows (for the most part) issues on soft tissues like joint capsules, tendons, and ligaments. For example, if we’ve localized lameness to the stifle, and radiographs don’t reveal any evidence of DJD, we can ultrasound the joint and evaluate a meniscus or the supporting ligaments. Early DJD may only demonstrate a thickened joint capsule on ultrasound.
If x-rays and/or ultrasound don’t give us adequate information, we can offer referral for either computed tomography (CT) or magnetic resonance imaging (MRI).
The earlier we identify DJD, the more treatment options we have, and there seem to be new treatment modalities developing almost monthly. Compared to the “old days” when I was fresh out of veterinary school it’s sometimes like a whirlwind. It used to be that cortisone was essentially the only choice in joint therapy. It is still a valuable tool in the arsenal, and the right form of cortisone, in the correct amount, at the appropriate interval can often be the best option.
In the next article, we’ll discuss differences in the approaches to management of DJD depending on the discipline involved. The third article will discuss the expanding range of therapeutic interventions available.
