Laceration of the entire Achilles tendon involving both the gastrocnemius and superficial flexor tendons is rare. The hock drops toward the ground and is unable to bear weight. The prognosis is grave.
Gastrocnemius muscle rupture is more common and can result from excess stress applied to the hock (eg, sudden stopping). It can be bilateral and some weight can be borne, but there is excess flexion of the hock, which makes walking difficult. There is no satisfactory treatment. Splinting the limb and slinging the horse have been tried and have resulted in some success. Generally, foals with this condition have a better prognosis.
Injuries to the long and lateral digital extensors, frequently accompany hindlimb lacerations. If one tendon is involved, the prognosis is usually good. If both extensor tendons are severed, the horse may be left with a gait deficit for performance, but it may be useful for pleasure riding or for breeding. Conservative treatment leads to wound healing, but surgical repair and casting should be considered if both tendons are severed or if performance status is desired.
The superficial and deep flexor tendons sometimes rupture as a racing injury or accompany lacerations. These are serious injuries with marked lameness and varying degrees of overextension of the fetlock and pastern. Treatment involves surgical repair with splinting and casting the limb, but the prognosis is poor for future performance.
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