Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 5
Arytenoid cartilages
Pharyngeal wall
Vocal fold
Laryngeal
aditus
Epiglottis
Soft palate
Figure 5.17 Endoscopic view of bovine
larynx.
5.17). The epiglottis is visible ventrally except when
the animal swallows and the soft palate moves
caudally to cover the larynx. The laryngeal aditus is
quite small in cattle and the movements of the vocal
folds which partially occlude the entrance are subtle.
In cases of laryngeal paralysis one or both folds do
not move laterally when the animal breaths in. When
laryngeal paralysis is associated with Fusobacterium
necrophorum infection, small quantities of green pus
may be seen adhering to the laryngeal cartilages.
Trachea To enter this the endoscope is advanced
towards the laryngeal aditus and then further advanced
carefully but quite quickly under the arytenoid
cartilages and between the vocal folds into the
trachea. The trachea appears circular in outline and
the inside of the cartilaginous tracheal rings are clearly
visible (Fig. 5.18). In normal animals little mucus is
present. Large amounts of mucopurulent material
may be seen on the ventral floor of the trachea and
possibly moving slightly with air flow in animals
with a respiratory infection. The endoscope is advanced
further into the trachea. The entrance to the
right apical lobe is seen, and further down the coryna
is identified at the point where the trachea divides
into two main stem bronchi. Just anterior to this point
a tracheal wash can be taken using the endoscope.
Eesophagus This is entered from the pharynx by
passing the endoscope over the top of the larynx
aided by swallowing movements of the patient. The
muscular oesophagus has a small lumen in its relaxed
state. Folds of mucosa are seen passing longitudinally
down towards the rumen (Fig. 5.19). These
folds disappear if the oesophagus is inflated by passing
air through the endoscope. Distension of the oesophagus
by inflation allows better evaluation of the
mucosa. The endoscope is gently advanced progressively
along the oesophagus and is directed to view
the mucosa checking for signs of injury or penetration.
Small ulcers may be seen in cases of mucosal
disease. In medium sized animals the endoscope can
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