By Jackie Bellamy-Zions, Equine Guelph
Radiographs have been found to be insufficient evidence for diagnosing cervical facet disease, according to a research study by Dr. Judith Koenig and a team of researchers at the Ontario Veterinary College (OVC). In a video interview, Koenig explains some of the complexities of equine osteoarthritis and cervical facet disease.
“Osteoarthritis is common in any athlete,” explains Koenig, “especially as they get older.” The development of bone spurs can cause the facets to become enlarged. Inflammation around the cervical facet joints can affect the soft tissues and nerve roots. It is hypothesized that slight neck instability or overuse can result in remodeling of the joint. There were a larger number of dressage horses relative to the hospital population in the study, and dressage horses may be at a higher risk for overuse of the facet joints of the cervical vertebrae.
Clinical signs of osteoarthritis in the neck include: atrophy/muscle wasting (pronounced hollow in lower neck and vertebrae appear prominent), stiff neck (e.g. limited range in carrot stretch, difficulty when ridden in a “frame”) and sometimes front limb lameness that does not resolve by nerve blocking up the leg.
Dr. Judith Koenig discusses osteoarthritis of the equine neck
One of the reasons for the OVC study was that previous studies had shown radiographs indicating changes in the neck of younger horses (six to eight years), with no other clinical signs of osteoarthritis. Koenig herself had seen horses dismissed after pre-purchase exams when radiographs indicated mild osteoarthritis. When previous studies indicated 50% of clinically normal mature horses present with mild osteoarthritis on radiographs, a study to explore the significance was in order.
Differing opinions in classifying the severity of the stage of osteoarthritis from radiographs is also a good case for not using radiographs alone in diagnosis. “The repeatability of grading of osteoarthritis from radiographs was not reliable,” says Koenig. Two thirds of the horses in the OVC study that were treated with intra-articular cortisone injection returned to their full level of work. The study concluded that radiographs alone were insufficient to diagnose cervical facet disease and other clinical signs (atrophy, stiffness, or lameness unresolved by nerve block) need to be present.