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This expression refers to the osteo-arthritis of the proximal interphalangeal joint and is a condition that affects multiple breeds. Predisposing factors are short upright pastern conformation and disciplines that make quick stops and hard turns with rapid twisting, such as Western performance and show jumpers. Also Paso Fino horses suffer commonly from this pathology.

High ring bone can occur in fore and hind limbs. The horse shows marked lameness and palpable enlargement of the pastern region and may be positive to flexion tests. The lameness is also increased after exercising the horse.

Confirmation of the source of lameness is performed by perineural anesthesia and radiographs to confirm the involvement of the joint.

Radiography confirms the osteo-arthritis and can occurs bilaterally, that’s why even though the horse may show clinical signs in only one limb, there might be radiographic changes in the opposite limb as well. It is very important to differentiate periarticular bony proliferation that is not involving the joint from the true intra-articular proximal interphalangeal osteo-arthritis (picture1, 2).



The intra-articular injection with corticosteroids is usually a short term solution. Pain can be managed also with bute but the only definitive solution is usually the surgical fusion of the joint. The goal of fusing the joint is to eliminate pain and allowing the horse to return to the previous level of performance.

The goal of surgery is to make a single bone from the pastern joint. It is accomplished by exposing the joint, destroy the remaining cartilage and placing a plate and screws to fix the joint. During the convalescence period the horse has to wear a cast for 2-3 weeks and time will fuse the joint in to a single bone eliminating the pain definitively.

Recently a new medical therapy has been developed by a group of Doctors from the University of Iowa in which the joint is injected with alcohol. The alcohol is very toxic to the cartilage cells producing its death and promoting the joint fusion. This novel treatment has been performed in a cases series with very encouraging results (picture 3).



Long term follow up showed very good prognosis with the surgical fusion of the joint with success rates of around 85% to 90% of the treated animals . The alcohol fusion therapy showed 90% of success at 8 months after a series of injections. This therapy has the advantage of simplicity, cheapness and fewer complications that can be encountered with surgery but more time and cases are needed for conclusive results.