Laryngeal Hemiplegia

In Horses:
Unilateral paralysis of arytenoids
Common 2-13% training thoroughbreds
Damaged/ dysfunctional recurrent laryngel nerve (branch of vagus)
Mostly left side affected, occasionally also the right nerve
Demyelination of nerve fibres, and leading to atrophy of intrinsic laryngeal muscles particularly the adductor (cricoarytenoid) which allows the left arytenoid cartilage to lean into the laryngeal lumen
The 'roaring' is noticeable after exercising
The aetiology is not properly established but suggested factors are:
- Length of the left recurrent nerve
- Extension neuritis in guttural pouch mycosis
- Neurotoxins - organophosphorus compounds may produce similar degenerative changes in the nerves
- Enlarged retropharyngeal lymph nodes
- Neoplasia
- Trauma

Test yourself with the Larynx Pathology Flashcards