• 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

• Part of neurologic examination   Neurology: examination - adult  .
• Crude assessment of vision and the cerebellum    Neurology: vision testing - overview  .

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.

Time required

Preparation

• None.

Procedure

• 5 min.

Decision taking

Criteria for choosing test

• Same as maze test   Neurology: vision testing - overview  .