Equis ISSN 2398-2977

Foot: underrun heels

Synonym(s): Sloping heels, collapsed heels, underslung heels, run under heels

Contributor(s): Graham Munroe, Vetstream Ltd

Introduction

  • A significant and common abnormal hoof conformation predisposing to lameness.
  • Cause: usually caused by incorrect trimming; long toes and short heels.
  • Signs: lameness; long toes, short heels; palmar or plantar face of the hoof wall diverges >5° from dorsal hoof wall; the heel grows forward under the foot.
  • Biomechanical changes include fetlock overextension, increased tension on flexor support mechanism, and increased energy required for foot breakover and altered flight of foot.
  • Diagnosis: signs.
  • Treatment: shorten toes, leave heels longer and support heels with slightly oversized shoe extending past heels.
  • Prognosis: depends on severity.
Print off the Owner factsheet on Caring for your horse's feet to give to your clients.

Pathogenesis

Etiology

  • Incorrect shoeing   Farriery: natural balance shoeing  /trimming   Foot: trimming and balancing  :
    • Leaving the toes too long or trimming the heels too much.
    • Using too small a shoe or leaving the shoe on too long increases the stresses on the heel making it prone to collapse.
    • Toe grabs and calks may alter the balance of a foot and again increase heel stress.
  • Thoroughbred horses or crosses may be genetically predisposed to this problem.
  • Young, unshod horses grazing for long periods on rich pasture.

Pathophysiology

  • Long toes, short heels   →   increased load on the distal portion of the palmar/plantar hoof wall   →   collapse of hoof wall.
  • Loss of parallel growth between dorsal hoof wall and palmar/plantar hoof wall   →   loss of bars and realignment of tubular and intertubular horn to ground surface   →   decreased resistance to compression and loss of weight-bearing strength.
  • Increased forces are applied to the hoof wall as the heels become low     →    the horn tubules at the heels bend to the point where they are unable to support the weight   →    horn tubule thinning, separating, collapse   →    roll underneath the foot.
  • Poor foot conformation   →   hyperextension of distal interphalangeal joint, overextension of fetlock and carpus, increased concussion to phalanges and increased tension of flexor support structures, increased likelihood of toe-first landing   →   increased predisposition to lameness.
  • May contribute to other foot related problems such as chronic heel pain and bruising, navicular bone pathology   Navicular bone: syndrome  , DIP joint injury and synovitis   DIP joint: disease - overview  , quarter and heel cracks   Foot: hoof wall fracture  , and interference problems   Musculoskeletal: gait evaluation  .

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.
  • Eliashar E (2007) An evidence-based assessment of the biomechanical effects of the common shoeing and farriery techniques. Vet Clin North Am Equine Pract 23 (2), 425-442 PubMed.
  • Kane A J et al (1998) Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred horses. Am J Vet Res 59 (12), 1545-1552 PubMed.

Other sources of information

  • O'Grady S E (2009) Guidelines for Trimming the Equine Foot: A Review. In: Proc 55th AAEP Convention. Las Vegas, Nevada.
  • O'Grady S E & Merrium J G (2007) Low Heels in the Hind Feet - An Often Overlooked Problem. Am Farriers J. Website: www.equinepodiatry.com/article_low_heels.htm.
  • Pollitt C C (1999) Ed. Color Atlas of the Horse's Foot. Mosby, UK. ISBN: 0723417652.


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