Page 799 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

774 CHAPTER 4

VetBooks.ir passage by peristalsis. Horses commonly continue to food, as well as demonstrate the presence of luminal
defects or a diverticulum (Fig. 4.101). The view may
eat after oesophageal obstruction, leading to a food
accumulation that extends proximally almost as far
many cases aspiration of food into the trachea will be
as the larynx. Oesophageal obstruction can also be be obscured by opaque liquid and suspended food. In
associated with autonomic dysfunction (e.g. with observed endoscopically, and the ensuing tracheitis
equine grass sickness). will lead to coughing.

Clinical presentation Management
Clinical signs of oesophageal obstruction include Oesophageal obstruction does not constitute a
anxiety, with elevated pulse and respiratory rates and serious acute emergency and many horses tolerate
sweating of the neck. An inability to swallow despite obstruction for 24 hours or more without signifi-
ongoing saliva production can lead to dehydration cant oesophageal mucosal damage. Nevertheless,
and electrolyte disturbances including hypochlor- the distress to the horse and owner and the potential
aemia if significant saliva losses are incurred. NG for electrolyte and fluid disturbances, dehydration,
reflux of food and saliva can be observed from both inhalation pneumonia and oesophageal ulceration
nostrils (Fig. 4.95). warrants prompt investigation.
Spontaneous clearing of the obstruction will
Differential diagnosis occur in many cases if relaxation of the oesopha-
Oesophageal diverticula, congenital anomalies, car- geal muscle spasm can be achieved. Smooth muscle
diac sphincter incompetence, grass sickness, botulism. relaxants such as N-butylscopolammonium bromide
(Buscopan), phenothiazine tranquillisers including
Diagnosis acepromazine and diazepam and alpha-2 agonists
Attempts to pass a NG tube will be met with resis- including xylazine, detomidine and romifidine, are
tance at the proximal end of the obstructing bolus. all used successfully. In addition to causing muscle
Oesophagoscopy will reveal the cranial extent of the relaxation, the alpha-2 agonists reduce anxiety and
bolus and saliva pooling and can indicate the type of sedation leads to a lowering of the head, which pro-
motes orad drainage of any food and saliva from the
pharynx and tracheal aspirates. Limited access to

4.101 small volumes of water can help with irrigation but
all food should be immediately withdrawn.
Softening of the bolus by irrigation with warm
water through a narrow NG irrigation tube can
be effective. Great care should be taken to avoid
excessive force when advancing the tube, which
could perforate the delicate oesophageal mucosa.
In addition, the horse should always be sufficiently
sedated that its head remains lowered throughout
the procedure to ensure that overflow exits the nos-
trils. The water should be infused slowly enough to
allow drainage around the tube without excessive
overflow into the trachea. It must be assumed that
some aspiration will occur during this procedure.
As the bolus is softened it is gradually removed with
the egress water, allowing cautious advancement of
the tube. Great patience is required to completely
Fig. 4.101 Oesophagoscopy showing an atypical remove the obstruction when the bolus is extensive.
obstruction with grass. Multilumen, cuffed oesophageal bougienage tubes