is a common condition of horses
, characterized by the ossification
of the collateral cartilages
of the coffin bone
. These are found on either side of the foot protruding above the level of the coronary band. The lateral cartilages support the hoof wall and provide an important role in the support and cushioning provided to the heel. The front feet are most commonly affected.
Causes of Sidebone
Repeated concussion of the foot is probably the cause in many cases. Such concussion could be produced when a horse is always worked on a hard surface. There also appears to be a hereditory component to sidebone but this may be because bad conformation is hereditary and bad conformation appears to predispose to sidebone. Bad conformation would include
- those with narrow, upright feet
- those with unbalanced feet, especially if they have toe-in or toe-out conformation
- draft horses, or horses with a draftish build, are more likely to develop sidebone than light horses or ponies
Symptoms associated with sidebone
Sidebone may be associated with lameness
but many horses with sidebone are not lame. It follows that sidebone often gets blamed for being the cause of lameness when there is actually another cause.
Diagnosis of Sidebone
Careful examination of the collateral cartilages by palpation
can give a good indication that they are solid and boney rather than firm, springy cartilage. Usually, however, sidebone is found accidentally when the foot is radiographed
, as sidebone has few outward signs in most cases. In mild cases, there are small areas of calcification; more advanced cases will have ossification of the entire cartilage. Rarely, severe lameness can be caused by fracture of an ossified cartilage, or by ossification which deviates enough to impinge on the short pastern bone.
Treatment of Sidebone
Sidebone usually does not cause any problems, but where it does it is difficult to treat. Box rest and Non-steroidal anti-inflammatory drugs
such as bute
may be useful. In some cases the only useful treatment is a neurectomy
of the palmar digital nerves.
Many horses compete actively in demanding sports with sidebone, and are not hindered in any way. If the ossification is severe and associated with lameness then the prognosis is more guarded. Discovery of sidebone on an equine prepurchase exam
without signs of lameness or local sensitivity should not affect the purchaser's opinion of the horse.
King, Christine, BVSc, MACVSc, and Mansmann, Richard, VDM, PhD. "Equine Lameness." Equine Research, Inc. 1997. Pages 689-691.