Fractures of the second and fourth metacarpal and metatarsal (splint) bones are not uncommon. The cause may be from direct trauma, such as interference by the contra-lateral leg or a kick, but often accompany or follow a suspensory desmitis (seesee Suspensory Desmitis in Horses) and the resulting fibrous tissue buildup and encapsulation of the distal, free end of the bone. The usual site of these fractures is through the distal end, ∼2 in. (5 cm) from the tip. Immediately after the fracture occurs, acute inflammation is present, usually involving the suspensory ligament. A supporting-leg lameness is noted, which may recede after several days rest and recur only after work.
Chronic, longstanding fractures cause a supporting-leg lameness at speed. Thickening of the suspensory ligament at and above the fracture site results. The fracture may show a considerable buildup of callus at the fracture site but little tendency to heal.
Diagnosis is confirmed by an oblique radiograph. Surgical removal of the fractured tip and callus is the treatment of choice. The prognosis is based on severity of the associated suspensory desmitis, which has a greater bearing on future performance than the splint fracture itself. More proximal splint fractures are usually treated with removal of excess callus.
Last full review/revision March 2012 by Stephen B. Adams, DVM, MS, DACVS; Joerg A. Auer, DrMedVet, Dr h c, MS, DACVS, DECVS; James K. Belknap, DVM, PhD, DACVS; Jane C. Boswell, MA, VetMB, CertVA, CertES (Orth), DECVS, MRCVS; Peter Clegg, MA, Vet MB, PhD, CertEO, DECVS, MRCVS; Andrew L. Crawford, BVetMed, CertES (Orth), MRCVS; Jean-Marie Denoix, DVM, PhD, Agregé; Marcus J. Head, BVetMed, MRCVS; C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, DACVS, DACVSMR; James Schumacher, DVM, MS, DACVS, MRCVS; John Schumacher, DVM, MS, DACVIM; Roger K. W. Smith, MA, VetMB, PhD, DEO, DECVS, MRCVS; Chris Whitton, BVSc, FACVSc, PhD