Before I started working on this case — a thoroughbred with sidebone — the owner had a very good local farrier. Not being a blacksmith, however, he could not build the required sidebone shoes himself — he provides only manufactured (prefabricated) shoes. The special sidebone shoes needed by this horse must have a thicker inside (medial) branch, tapering off to alleviate pressure on the calcifying tissue. So the owner's son-in-law, a farrier back east, was building the sidebone shoes and shipping them across the country for each setting by the local farrier. But with work and wear over time, a horse's feet are continually changing. So having a far-away farrier build the shoes without direct access to the animal was not an optimal plan. I was called in to see if I could help out. Now I visit every five weeks to care for this horse's feet. I can build and adjust the sidebone shoes on location, ensuring that the fit is correct every time.
Sidebone is often loosely lumped into the ringbone category. Ringbone in horses is a catch-all phrase that generally refers to the process of tissues hardening and eventually turning into bone through calcification (the formation of excess mineral deposits) and subsequent ossification (the conversion of these mineral deposits into bone). This is a degenerative, often debilitating, arthritic syndrome that interferes with joint function and flexibility. Ringbone describes the affect of this process on the connective tissues surrounding the pastern bones, while sidebone affects the foot of the horse, specifically referring to the ossification of the cartilages that extend backward from the sides of the coffin bone to the heel bulb. As these cartilages harden and lose elasticity, the ability of the hoof to expand and contract with the impact of each stride becomes limited, bloodflow in the foot is reduced, and further calcification of the small ligaments connecting with the pastern, coffin and navicular bones may occur. Ultimately, sidebone can lead to pain and lameness.
The causes of ringbone and sidebone are still unconfirmed, but may stem from direct trauma to the foot, poor hoof confirmation, upper limb issues, imbalanced feet or improper trimming and shoeing. It is often seen in older horses who have worked on hard surfaces most of their lives, and in past centuries was considered an inevitability for the harness horses used to pull carriages and wagons transporting passengers and goods on cobblestone streets. Because ringbone and sidebone are most often seen in certain breeds of horses — typically drafts — heredity may play a part, but this has not yet been scientifically determined.
Heat, swelling, a shortened or shuffling stride, as well as the development of bony ridges are all signs to pay attention to. But appearances may be deceiving — “false ringbone,” which produces similar symptoms to real ringbone is actually an inflammation involving ligaments rather than being caused by calcification, and can usually be resolved with rest. True ringbone and sidebone, however, are degenerative diseases for which there is no known cure; although once confirmed they can, like many other equine arthritic conditions, be managed to reduce further progress of calcification and its consequent effects.
A horse displaying signs of lameness should be seen by a veterinarian to diagnose the cause. Medical imaging can show evidence of ringbone or sidebone — or rule these conditions out. Prescribed treatment may include rest, anti-inflammatory medication and therapeutic shoeing by a qualified farrier. Veterinary follow-up is recommended to assess progress. Today, with early recognition and intervention, neither ringbone nor sidebone is likely to end your horse’s career, but may suggest that it’s time to start dialing back a bit on the athletic demands you place on him as he ages.