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**Trauma
**Trauma
* These horses are also known as "'''roarers'''"
* Equine laryngeal hemiplegia is a very common condition.
===Pathogenesis===
# The disease starts with an idiopathic degeneration of the left recurrent laryngeal nerve.
# This leads to atrophy of the left dorsal cricoarytenoid muscle.
# Without the use of this muscle, the horse is unable to abduct the left arytenoid cartilage and vocal fold.
# Airways are therefore partially obstructed on inspiration.
[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_KSsrch&kw=HEMIPLEGIA View images courtesy of Cornell Veterinary Medicine]
Idiopathic Laryngeal Hemiplegia:
:Progressive loss of fibres (esp. large diameter) within left recurrent laryngeal nerve compared to right
:Dying back axonopathy with myelin sheath involvement:
:Degenerating fibres
:Regenerating clusters
:De/Re-myelination
:Flattening of nerve between aorta & trachea
:Inspiratory 'roaring' noise - flapping of vocal fold
:'Slap test' - adduction of contralateral arytenoid during expiration
:Endoscopic examination - assymetric arytenoids, poor abduction of left vocal fold.
:Palpable atrophy of laryngeal musculature
:Laryngeal Ventriculectomy (Hobday procedure)
:'Tie Back'
:Laryngeal muscle prosthesis
:Prognosis usually good
==Test yourself with the Larynx Pathology Flashcards==
==Test yourself with the Larynx Pathology Flashcards==
[[Category:Larynx - Pathology]]
[[Category:Larynx - Pathology]]
[[Category:Respiratory System - Degenerative Pathology]]
[[Category:Respiratory System - Degenerative Pathology]]
[[Category:Respiratory Diseases - Horse]]
[[Category:Central Nervous System - Degenerative Pathology]]
[[Category:Peripheral Nervous System - Pathology]]