Page 622 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Respir atory system: 3.2 Surgical conditions of the respir atory tr act 597

VetBooks.ir 3.2 Surgical conditions of the respiratory tract

NOSTRIL

ALAR FOLD DISEASE (REDUNDANT/ only and cause no clinical effects. The noise in these
HYPERTROPHY/COLLAPSE/STENOSIS) circumstances is usually louder at the beginning of
work and decreases with increasing exercise. Other
Definition/overview causes of abnormal respiratory noise and nostril trau-
The alar fold forms the ventral aspect of the nasal matic damage and deviation should be considered.
diverticulum (false nostril) and divides it from the
rostral nasal passage. It extends from the alar carti- Diagnosis
lage caudally to the rostral aspect of the ventral nasal Confirmation that the noise is derived from the
concha. The fleshy fold, which is lined by mucous alar folds is best achieved by placing a temporary
membrane, is elevated during exercise and closes off mattress suture through the dorsal nostril and then
the entrance into the false nostril (Fig. 3.8). Failure the false nostril, before taking it over the bridge
of function, or abnormalities, of the alar fold can lead of the nares and passing it through the other side in
to an abnormal inspiratory noise at exercise. Surgical the same manner (Fig. 3.9). The suture is tied on
resection of the fold can be effective. top of a swab in the midline of the dorsal nares. The
suture is placed under local anaesthesia. The horse
Aetiology/pathophysiology is examined before and after suture placement to
The cause varies between individual cases, but pos-
sibilities include increased size or thickening of the
alar folds, or abnormal function of the transversus 3.8
nasi muscle (the main elevator of the alar cartilages).
Individuals with abnormally narrowed nostrils may
also suffer from similar problems. In some reports
the American Saddlebred horse and Standardbreds
were thought to be more commonly affected because
of possible genetic conformation abnormalities of
the nostril region.

Clinical presentation
Affected animals present with a loud vibratory noise
from the nostril region at exercise, particularly at
faster gaits, usually at expiration and inspiration
with the former usually louder, and with variable
effects on exercise tolerance due to increased airway
resistance. In rare cases, noises have been noted at
rest. There may or may not be an abnormal nostril
or false nostril conformation. Occasionally the folds
are still collapsed into the nostril at the end of work
and can be observed.

Differential diagnosis Fig. 3.8 Air in the false nostril of a Thoroughbred
High blowing is a term used to differentiate a normal racehorse at exercise. This is probably a normal
situation where the folds vibrate during expiration finding. (Photo courtesy Richard Seale)