Curb refers to a thickening or bowing of the plantar tarsal ligament due to strain. This ligament may become inflamed and thickened after falling, slipping, jumping, or pulling. This problem is most common in Standardbreds, in which poor conformation of the hock is a predisposing factor. There is an enlargement over the caudal surface of the fibular tarsal bone ~4 in. (10 cm) below the point of the hock. It is easily seen when observing the horse from the side. A recently formed curb is associated with acute inflammation and lameness. The horse stands and favors the limb with the heel elevated. In chronic cases, there is rarely any lameness or pain.
If the curb is due to acute inflammation, cold packs and rest are indicated. Little can be done to overcome the curb that is secondary to poor conformation. Fortunately, the problem seems to be self-limiting, without lasting effects on performance.
A curb-like lesion can be observed in foals with incomplete ossification at the time of birth. If these conditions are not properly managed with tube casts or splint bandages and the foal confined to box stall rest, the precursor cartilage still present in the small tarsal bones may become thin and eventually rupture, resulting in a partial forward collapse of the tarsus and the appearance of the curb-like contour. These animals are lame, but once ankylosis of the small tarsal joints occurs, which may take months, the lameness disappears.
Last full review/revision March 2012 by Stephen B. Adams, DVM, MS, DACVS; Andrew L. Crawford, BVetMed, CertES (Orth), MRCVS; 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; Marcus J. Head, BVetMed, MRCVS; C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, DACVS; James Schumacher, DVM, MS, DACVS, MRCVS; John Schumacher, DVM, MS, DACVS, MRCVS; Roger K. W. Smith, MA, VetMB, PhD, DEO, DECVS, MRCVS; Chris Whitton, BVSc, FACVSc, PhD; Jean-Marie Denoix, DVM, PhD, Agregé; Joerg A. Auer, DrMedVet, Dr h c, MS, DACVS, DECVS