Proceedings of a Workshop on - The Havemeyer Foundation

Equine Recurrent Laryngeal Neuropathy
TABLE 2: Reasons for and number <strong>of</strong> horses failing conditions <strong>of</strong> sale at the National Yearling Sales
(1997– 2002)
Condition Number Comments
Arytenoid chondritis 12 Some horses with focal lesions have been
treated by debridement and have been
sold or are racing
Epiglottic entrapment 5 All treated and sold
Persistent dorsal displacement <strong>of</strong> 2 Both resolved with antibiotic/antis<strong>of</strong>t
palate
inflammatory treatment
Right side Grade 4 or 5 3 Aetiology unknown
laryngeal movements
1 horse had grade 4 laryngeal
movements and rostral displacement <strong>of</strong>
the palatopharyngeal arch
Right side Grade 4 or 5 4 3 dorsopharyngeal masses
movements due to mechanical
1 severe epiglottic inflammation
obstruction
All resolved with treatment
Left side Grade 4 or 5
laryngeal movements (ILH) 8 1 horse had what appeared to be a
unilateral rostral displacement <strong>of</strong> the
pharyngeal arch as well as ILH
7 horses ILH
Left side Grade 4 or 5 laryngeal 2 1 dorso pharyngeal mass
movements due to mechanical
1 severe epiglottic inflammation
obstruction
All resolved with treatment
Rostral displacement 3
palatopharyngeal arch
Chondritis left side <strong>of</strong> epiglottis 1 Failed because the chondritis
resulted in an obstruction <strong>of</strong> the rima
glottidis
Hypoplasia <strong>of</strong>
s<strong>of</strong>t palate 1 Broken in, trialled but retired
examinations at sales around the world, the
problem is unusually common in New Zealand.
The exact reasons for this are unknown.
In addition, a number <strong>of</strong> horses have been
recognised that have arytenoid mucosal injury
(Anderson 2000). These mucosal injuries manifest
as small erosions/ulcers, or alternatively, raised
areas <strong>of</strong> epithelial injury. They are found on the
medial surface <strong>of</strong> each arytenoid just above where
the vocal cords join onto the arytenoid cartilages
(the vocal processes) and may also be found on the
vocal cords themselves. They may be hyperaemic
or even have small, slightly purulent centres and
can vary in colour from red to white. Although
occasionally unilateral most <strong>of</strong>ten there are 2
lesions, one on either cartilage and they are
referred to as ‘kissing lesions’. Even if there
appears to be only one lesion, close scrutiny <strong>of</strong> the
opposite arytenoid cartilage usually reveals a
small area <strong>of</strong> accompanying injury. The exact
cause <strong>of</strong> these lesions is not known. Reports in the
literature regarding such lesions in horses are
sparse but they have been reported in yearling
Thoroughbreds at horse sales in Australia (Kelly et
al. 2003). Review <strong>of</strong> laryngeal diseases and
injuries in man, cattle and other species indicates
that the cause(s) <strong>of</strong> these injuries is likely
multifactorial with infectious causes having a
major role (Fig 1). Mucosal inflammation or
mucositis occurs and is followed by mucosal
ulceration when the superficial epthelium is
denuded. Because there is no submucosa, the
mucosal epithelial layer is tightly adhered to the
underlying perichondrium <strong>of</strong> the arytenoid
cartilage. Pressure, the result <strong>of</strong> both intrinsic and
extrinsic trauma over the thin, relatively immobile,
mucosal layer results in erosion and ulceration.
Once the mucosal barrier is breeched bacterial
infection <strong>of</strong> the underlying structures is possible.
If the infection remains localised a relatively quick
healing response occurs with or without the use <strong>of</strong>
antibitotic/anti-inflammatory treatment. Healing
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