By: Katie Jones, CVT
Your riding horse has just been diagnosed with ringbone, a degenerative disorder which affects pastern and coffin joints and has no cure. Before you automatically write him off as a pasture ornament, please consider the related advances in diagnosis, treatment, and shoeing practices. Due to advancements, this condition is no longer an automatic career-ending diagnosis.
What is Ringbone? Ringbone is exostosis (bone growth) which affects the pastern and coffin joint in the horse. Ringbone is considered an osteoarthritic condition; there are two classifications. The first is “high ringbone”. This occurs on the lower end of the larger pastern or the upper portion of the small pastern bone. The second is “low ringbone”. As the name implies, it occurs on the lower part of the small pastern bone or the upper portion of the coffin bone. Ringbone can range from a mild to severe case dependent on how the horse handles pain. Ringbone is most commonly found in the front legs; typically one leg will be worse then the other. In addition, it is most commonly seen in mature horses in intensive work routines.
The cause of ringbone varies. Excessive tension on tendons and ligaments of the pastern area can strain the membrane covering the outer surface of the bone (periosteum) causing stretching or tearing of the soft tissue structures. This then can lead to the joint becoming unstable due to the injury, ultimately causing new bone to be produced to immobilize the joint. This immobilization relieves inflammation within the joint capsule and leads to the development of osteoarthritis in the joint. If this is occurring, pain continues until the joint is completely immobilized (fussed). Another cause of ringbone can be poor showing and conformation issues. Conformational issues such as long sloping pastern angels, upright pasterns, long toes with high heels, overall unbalanced feet, and conditions such as splayed feet or pigeon toes, can all predispose a horse to ringbone. Due to the angle issues associated with foot conformational issues, uneven stress on the pastern, coffin joint, and soft tissues structures which surround the joint can be seen. The time it takes for this damage to form the build-up of bone will vary based on the severity of the initial trauma.
The process of confirming the presence of ringbone should start with a thorough lameness exam. Based on flexion tests, joint blocks may be performed to confirm the causing pain is originating from either the coffin or pastern joint. Once the lameness exam is complete, the veterinarian will typically recommend radiographs be taken of the area. Radiographs are used to show boney changes in the joint surface, which should otherwise be smooth.
Ringbone is degenerative, but can be managed. Treatment plans are geared, not to cure it, but aimed at slowing down the process of boney growth and alleviating the pain it causes. Some of the treatment options available are: proper shoeing, NSAIDs to relieve pain and inflammation in the joints, joint injections, shockwave therapy, or in more advance cases, joints can be fused. The rate of degeneration and the amount of damage seen when a horse is diagnosed with Ringbone will influence which treatment option a veterinarian recommends for a specific patient.
Though Ringbone can limit or compromise a horse’s ability to do its job, early diagnosis and corrective measures can help prevent it from becoming more advanced. If you have concerns regarding ringbone or if your horse may have it, please contact your local veterinarian to schedule a lameness evaluation.