Equis ISSN 2398-2977

Anesthesia: peri-operative complications - post-operative myopathy

Contributor(s): Leah Bradbury, Mark Senior

Introduction

Contributing factors

  • Myopathy and neuropathy are one of the possible causes of post operative lameness in the horse.
  • Can be localized to one muscle group or a generalized presentation where several or all muscle groups are affected.
  • Complex etiology.
  • Clinical signs may take from 15 min to several hours to develop.
  • Myopathies present as very painful and swollen muscles with sweating and reluctance to move.
  • Neuropathies have similar symptoms however as only the nerves are involved there is no pain, eg radial nerve cannot extend the elbow and use the body to propel the leg forward.
  • Myopathies and neuropathies may however occur together.
  • Many contributing factors listed below:
    • Ischemia (poor perfusion, hypotension, occlusion, compartmentalization, reperfusion injury).
    • Hypoxia.
    • Prolonged anesthesia time (>2 h).
    • Repeated anesthesia.
    • Poor positioning.
    • Poor padding.
    • Recent exercise.
    • Inadequate support/bedding.
  • Muscle groups that may be affected include:
    • Tricep.
    • Infraspinatus.
    • Supraspinatus.
    • Semitendinosus.
    • Pectorals.
    • Brachiocephalic.
    • Deltoid.
    • Ribcage.
    • Masseter in lateral recumbency.
    • Gluteals and longissiumus dorsi in dorsal recumbency.
  • Some breed predilection, eg draught horses   Irish Draught  and equine polysaccharide storage disease   Muscle: myopathy - exertional rhabdomyolysis  , heavy horses more prone to spinal cord malacia and Appaloosa   Appaloosa  and Quarterhorses   Quarterhorse  more prone to hyperkalemic periodic paralysis (HYPP)   Muscle: hyperkalemic periodic paralysis      Anesthesia: peri-operative complications - hyperkalemic periodic paralysis  .

Etiology

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Diagnosis

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Differential diagnosis

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Treatment

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Prevention

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Klein L, Ailes N, Fackelman G E, Kellon E & Rosenberg H (1989) Postanaesthetic equine myopathy suggestive of malignant hyperthermia. Vet Surg 18 (6), 479-482 PubMed.

Other sources of information

  • Taylor P M & Clarke K W (1999) Handbook of Equine Anaesthesia. W B Saunders.
  • Muir W H & Hubbell J A (1991) Equine Anaesthesia Monitoring and Emergency Therapy. Mosby, USA.


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