Known as a very common condition in horses, osteoarthritis, most commonly called arthrosis, refers to an articular cartilage damage, to an osseous remodeling and to a peri-articular soft tissue modification.
Most of the time it is a degenerative condition, resulting from articulations ageing. However, lot of other conditions may lead to horse’s arthrosis. A strenuous work, a bad conformation, an articular instability, articular cartilage damages or still trauma or infections can generate an early arthrosis development. We can really talk about vicious circle because this disease is « self deteriorating ».
A careful exam of the static horse may reveal first signs of an osteoarthritic process. An articular distension for example may be discovered with a detailed limbs palpation. An increase of the articular volume can be attributed to an increase of synovial fluid, creating what we can call « molette » or « vessigon ». It can also be attributed to a thickening of the articular capsule and to osseous proliferations on the articular margins. Limbs manipulation may reveal articular stiffness.
A dynamic exam may reveal a lameness, more or less important on a horse suffering from arthrosis. Standard presentation of arthrosis process on one limb is an exacerbated lameness at the beginning of the work and on a hard ground. Although they are non specific, these signs would be the first to seek when arthrosis is suspected.
Arthrosis suspicion is confirmed with imaging exams. Radiography and ultrasound are used to make the definitive diagnosis, but sometimes more modern technologies are needed such as MRI, scanner or scintigraphy.
Radiography exam will show osseous articular or peri-articular remodeling (osteophytes). On an X-ray, osteophytes look like anarchic osseous proliferations on articular margins. Affected articulations may also present a reduced articular space, indicator of damages on the cartilage covering the bone.
Finally, last radiographic element is remodeling of the sub chondral bone (bone under the cartilage), consisting of increase or decrease of bone density on the X-ray.
Ultrasound can show cartilage damages, thickening of the articular capsule and synovial membrane hypertrophy, signs of articular inflammation. Osteophytes can also be seen with this exam.
Once diagnosis is made, treatment of arthrosis is made with many axes.
First of all, a good trimming and shoeing is essential, studied with both the vet and the blacksmith, and may provide good results, especially on the distal joints (foot, pastern, fetlock). With specific shoes, the articular bio-dynamic can be changed : stress like articular pinch during sharp turns will be decreased, leading to a pain decrease and to an arthrosis process development decrease. To reduce stress on the joints, a « rolling » shoe facilitates foot rocker and limits tensions during movement. Branches cover of the shoe can also be adapted to increase foot sinking on a soft ground on the side (intern or extern) of the arthrosis. It will reduce compression on the affected articular areas.
Work should also be adapted. A regular and well-reasoned work have to be set. Long rest periods have to be avoided if possible. A good warm-up and work on a soft ground have to be preferred.
In addition to these conservative measures, medical treatments are available to control the arthrosis process. Oral pain killers may be used to control the pain. Mainly used during acute phase of the disease, they reduce intra and extra articular inflammation. Corticosteroids and hyaluronic acid intra articular injections can also be suggested to manage long term articular damages. Injections should be sparingly used to keep their beneficial effects effective.
As osseous remodeling are often detected during arthosis process, biphosphonates use can be appropriate to manage mild term pathologies. Decreasing the osseous inflammation, this molecule can reduce consequences on the arthrosic bone.
Novel therapeutics are born in the last few years such as IRAP (autologous serum stopping the inflammation cascade). It is acting as an anti-inflammatory drug and is produced by the horse himself. Many injections can be made in the affected articulation. The biggest benefit is not to induce unwanted effects on the articulation and not to be considered as a doping product.
Stem cells are subject of many scientific research about arthrosis treatment and first results seem to be promising.
According to the arthrosis degree, all of these treatments may increase comfort and extend the sport carreer, or offer a confortable retired life to your horse.
Dr Perinne PIAT