Page 661 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

636 CHAPTER 3

VetBooks.ir 3.73 Clinical presentation
Pharyngeal collapse associated with surround-
ing swelling will present with significant dyspnoea
(Fig. 3.73). The horse may have marked stertor at
rest and stand with the head extended. Dynamic
pharyngeal collapse presents as a dynamic airway
obstruction of the performance horse with associ-
ated signs of exercise intolerance and abnormal respi-
ratory noise. Collapse of the ventral nasopharynx, or
billowing of the soft palate, is a specific obstruction
noted on dynamic endoscopy.

Differential diagnosis
Fig. 3.73 Pharyngeal collapse resulting in dyspnoea, The presenting signs of dynamic pharyngeal col-
secondary to haemorrhage and swelling into the lapse may lead to a tentative diagnosis of DDSP
guttural pouch. but are not specific enough to reliably rule out any
of the other airway obstructions of the perfor-
mance horse. The principal differential diagnosis
3.74
of permanent pharyngeal collapse is nasal occlu-
sion or severe recurrent obstructive lower airway
disease.

Diagnosis
Permanent pharyngeal collapse is readily diag-
nosed by endoscopy. Unless the pharynx is so col-
lapsed to preclude careful examination, the area of
the swelling will provide valuable information as
to the location of the swollen tissue. Further exami-
nation of the guttural pouches is indicated to assess
swelling in this area. Oral examination should not
be forgotten – abnormalities such as fractures of the
sixth cheek tooth can result in severe swelling and
respiratory obstruction.
Radiography may also be helpful in the diag-
nosis of permanent pharyngeal collapse; however,
this can be frustratingly non-specific, just show-
ing soft-tissue swelling which has already been
appreciated by endoscopy. Dynamic pharyngeal
Fig. 3.74 Overground endoscopy of dynamic collapse requires dynamic endoscopy for diagno-
pharyngeal collapse at exercise, in a 9-year-old sis (Fig. 3.74). A suspicion of the diagnosis can
Warmblood stallion used for dressage.
be obtained if pharyngeal collapse is observed fol-
lowing nasal occlusion during endoscopy at rest,
such as guttural pouch empyema or lymph node but this is little more than speculative. Similarly,
swelling can lead to pharyngeal collapse. In compe- development of respiratory obstruction when the
tition horses required to perform ‘in an outline’ (i.e. horse is brought ‘on the bit’ is suspicious but is not
with ventral flexion of the poll), pharyngeal collapse diagnostic as most respiratory obstructions are
can result from the physical positioning of the head. exacerbated by this ‘outline’.