Equis ISSN 2398-2977

Neurology: menace reflex

Contributor(s): Ruth Morgan, Graham Munroe

Introduction

  • The menace reflex is a complex learned reflex.
  • Afferent pathway:
    • Optic nerve   →   crossover at optic chiasm   →   lateral geniculate nucleus   →    visual cortex.
  • Efferent pathway:
    • Visual cortex   →   projections to the motor cortex and cerebellum via the pontine nucleus   →    ipsilateral facial nucleus   →   auriculo-palpebral nerve   →   orbicularis oculi muscle.

Uses

Advantages

  • Easy to perform.
  • No equipment required.

Disadvantages

  • Interpretation may be difficult as response can be variable, but in general horses have a brisk menace reflex.
  • Not useful in young foals due to variable development of reflex in first two weeks of life as this is a learned response.
  • Can be affected by a number of neurologic disorders such as facial paralysis and cerebellar diseases   Cerebellum: hypoplasia  .
  • Stoic, depressed or excited animals may not blink to menace reflex.

Requirements

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Preparation

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Procedure

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Enzerik E (1998) The menace response and pupillary light reflex in neonatal foals. Equine Vet J 30, 546-548 PubMed.


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