Equis ISSN 2398-2977

Distal phalanx: pedal osteitis - septic

Synonym(s): Infectious osteitis, P3 osteomyelitis

Contributor(s): Gordon Baker, Olin Balch, Graham Munroe, Chris Whitton

Introduction

Print off the Owner factsheet on Penetrating foot injuries to give to your clients.

Pathogenesis

Etiology

Predisposing factors

General

Specific

  • Foot trauma or penetrations.
  • Laminitis may result in recurrent abscessation and/or blood supply changes which can   →    osteomyelitis +/- sequestrum formation of P3.

Pathophysiology

  • Characterized by osteolytic change in the distal phalanx due to bacterial infection in the bone.
  • Usually results from introduction of environmental pathogens deep into the soft tissues of the foot with subsequent extension of the infection into adjacent distal phalangeal bone.
  • Usually cases have a history of foot penetration and/or trauma or chronic hoof disease.
  • Infection gains entry via penetrations or hoof defects.
  • The blood supply to P3 is superficially disrupted   →   ischemic necrosis which may be exacerbated by chronic bone exposure or damage plus localized infection.
  • Sequestration and/or pathological fractures may occur in chronic cases.
  • Infection:
    • Penetration of solar or dorsal wall horn via injuries or hoof defects.
    • Contamination of subsolar bruise or hematoma either at time of injury or subsequently via microcracks in damaged horn tubules.
  • Osteitis:
    • Disruption of cortical or superficial bone vascular supply.
    • Ischemic necrosis may also occur subsequent to chronic exposure and damage to the periosteum and superficial bone.
    • The localized infection will exacerbate the necrosis as well as damaging the soft tissues and laminae of the hoof.
    • Sequestration of focal bone areas can occur in chronic cases.
    • Subsequent demineralization of the distal phalanx through chronic disease and septic necrosis can   →   to pathological fractures of P3   Distal phalanx: fractures  .
    • Poor drainage of infection due to encasement in keratinized horn which is resistant to liquefaction.
    • Inflammatory exudate and/or pus drains via tracts in the sole or at the coronary band.
    • Inflammation causes pain and lameness.

Timecourse

  • After an initial acute lameness epidose the lameness may subside for several days/weeks until such a time as the osteitis produces enough pain to cause a recurrence of the lameness or inflammatory exudate tracts to the surface.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • O'Neill H & O'Meara (2010)Diagnosis and treatment of penetrating injuries of the hoof in horses.In Pract32(10),484-490 VetMedResource.
  • Cauvin E R & Munroe G A (1998)Septic osteitis of the distal phalanx - findings and surgical treatment in 18 cases.Equine Vet J30, 512-519 PubMed.
  • Gaughan E Met al(1989)Surgical treatment of septic pedal osteitis in horses, nine cases (1980-1987).JAVMA195(8), 1131-1134 PubMed.
  • Reeves M Jet al(1989)Miscellaneous conditions of the equine foot.Vet Clin North Am Equine Pract5(1), 221-242 PubMed.


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