"Sidebone" is calcification of the collateral cartilages of the hoof. It seldom causes lameness. ©EQUUS Magazine
Q: My 15-year-old half-draft mare has had on-and-off lameness for the past year and was diagnosed with sidebone in her right forefoot. The barn veterinarian injected her with cortisone, but after two weeks of rest she continues to carry herself differently. She doesn't bob her head but she "swivels" her left front hoof to limit the amount of time her right front carries her weight. And when at rest, she points her right forefoot forward without bearing weight on it, which is causing separation within. She has isolated herself from the rest of the herd and stands in the muddiest part of the lot.
My farrier has suggested putting shoes and pads on her. However, due to past trauma, this mare has issues with having her feet trimmed. After working with her for several months, I have gotten her to stand for the farrier. However, I am not sure if she will tolerate shoes. Are shoes her only option?
I have read that lameness isn't caused by sidebone but is a symptom of another problem. What could be causing my mare's lameness and what I can do to help her return to soundness?
A: The problems you describe---lameness, altered gait, standing in mud---all point not to sidebone but to laminitis, the inflammation of the soft connective tissues within the hoof. Of course, I'd have to examine your horse to be sure, but based solely on your description, I can make a good guess.
A horse with laminitis will typically point the affected foot forward and seek out cool surroundings or water. As the problem progresses, wall separation in the toe will develop. You'll need to call your veterinarian for a definitive diagnosis, a process that will likely include taking x-rays of the foot.
In my experience, the most effective treatment for mild laminitis is a properly applied heartbar shoe. If the coffin bone has become detached from the hoof wall and rotated down toward the sole (a condition called founder), pour-in padding will make the horse more comfortable. And, yes, you will need to continue to train your horse to accept the farrier, because if she has laminitis, she will need long-term expert hoof care to keep her comfortable.
Sidebone rarely causes lameness. This condition is the calcification of the collateral cartilages within the hoof---in other words, the pliable cartilage tissue ossifies, or develops into hardened bone. Sidebone is more common in heavy horses, and I have seen it most often in those who are toed-in. If the calcified cartilage fractures, the horse may have a little period of mild lameness, but not the disabling problem you describe.
Mike Miller, MD, CJF, FWCF