Page 293 - Clinical Manual of Small Animal Endosurgery

Small Exotic Animal Endosurgery 281

patient hypothermia. Endoscopy is not advisable for crop or proventricu-
lar biopsy in the diagnosis of proventricular dilatation syndrome, a gas-
trointestinal motility disorder, due to the risk of perforation.

Coelioscopy
Coelioscopy is without doubt the mainstay of avian endoscopy, and
essential in diagnostic investigation of conditions such as Aspergillus
fungal air sacculitis, and differentiating causes of avian hepatitis.

Coelioscopy entry sites
The selection of the entry site is dependent on the results of other imaging
modalities such as radiography, and the anticipated pathology and its
location. The left lateral approach is most common, due to avian endos-
copy’s original application for sexing. Most avian species in fact only
have an ovary on the left side. A right lateral approach may be used to
assess the pancreas in some birds, or to investigate a right-sided lesion
visualised on radiographs. A ventral midline approach is particularly
useful in visualising the liver. The ventral approach can generally be
safely used in cases of ascites, as the endoscope enters the hepatoperito-
neal cavity without entering the air-sac system. An interclavicular
approach can be used to assess the cervical air sacs, external trachea and
syrinx, and in some species the thyroid glands. Care needs to be taken
not to perforate the crop in species that possess one, and this may require
a larger entry incision. While this approach is useful in larger zoo avian
species such as penguins, it is rarely used in pet psittacines and diurnal
raptors.
Any space-occupying structures, such as eggs, will notably reduce the
space available for coelioscopic examination.
Birds should preferably be starved before endoscopy to reduce the risk
of perforating the proventriculus, which can result in fatal coelomitis.
Feathers should be plucked rather than cut, as these will then rapidly
regrow. Minimal plucking is generally required. Surgical skin prepara-
tion is as for any sterile surgery.

Left lateral coelioscopy approach
Birds are positioned on their right side and the left wing secured dorsally.
Lack of muscle tension in this wing also helps determine whether anaes-
thetic depth is sufficient to proceed with coelioscopy. The left leg may
be either pulled caudally or cranially. When the leg is pulled caudally,
the endoscope is inserted in the middle of a triangle formed by the caudal
border of the last rib, the spine dorsally and the cranial edge of the ili-
otibialis muscle (Fig. 10.4). If the leg is pulled cranially, the endoscope
is again inserted behind the last rib, and ventral to the flexor cruris
medialis muscle, which runs from caudal to the stifle to the ischium. In