Equis ISSN 2398-2977

Foot: flexural deformity - hyperextension

Synonym(s): Flexural deformity

Contributor(s): Steve Adair, Graham Munroe, Vetstream Ltd, Chris Whitton

Introduction

  • Cause: congenital or acquired laxity in flexor tendons.
  • Signs: bilateral hindlegs, or all limbs affected.
  • Diagnosis: physical examination, radiography.
  • Treatment: farriery, exercise, protective bandages .
  • Prognosis: good.
Print off the Owner factsheet on Flexural limb deformities to give to your clients.

Pathogenesis

Etiology

  • The exact etiology in unknown in the congenital form but may involve a physiological variation or a temporary failure of agonist/antagonist muscle balance.
  • The condition is often more common and severe in foals that are premature, dysmature and/or systematically ill Reproduction: prematurity / dysmaturity.
  • Lack of exercise in young foals may exacerbate existing weakness or cause failure to resolve.
  • Acquired condition is a rare complication of prolonged casting, splinting or bandaging particularly if the foot has been included Musculoskeletal: external fixation - casts.

Predisposing factors

General

  • Systemic illness in young foals.

Specific

  • Prolonged casting or splinting of distal limb.

Pathophysiology

  • Increased extensibility in flexor tendons → overextension of interphalangeal joints, fetlocks, hocks +/- other joints → failure to correctly weightbear on foot → abnormal foot wear (rocker heel) further exacerbating the deformity; possible soft tissue damage due to weightbearing on palmar/plantar aspect of fetlock.
  • Congenital: unknown.
  • Acquired: prolonged absence of weight bearing due to cast or illness → weak tendons.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Boerma S, Back W & Sloet van Oldruitenborgh-Oosterbaan M M (2012) The Friesian horse breed: A clinical challenge to the equine veterinarian? Equine Vet Educ 24 (2), 66-71 VetMedResource.
  • Curtis S J & Stoneham S (1999) Effective farriery treatment of hypoflexion tendons (severe digital hyperextension) in a foal. Equine Vet Educ 11 (5) 256-259 VetMedResource.
  • Kaneps A J & Smith B L (1998) Management of distal limb lameness in foals. Comp Cont Educ 20, 1060-1066 VetMedResource.
  • Munroe G A & Chan C H (1996) Congenital flexural deformities of the foal. Equine Vet Educ (2), 92-96 VetMedResource.
  • Fackelman G E & Clodiu L (1972) Surgical correction of the digital hyperextension deformity in foals. Vet Med Small Anim Clin 67, 1116 PubMed.


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