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Exotic Animal Endoscopy Course
© Stephen Hernandez-Divers, The University of Georgia Reptile Endoscopy With the animal adequately anesthetized, the reptile can be appropriately positioned depending upon the route of entry. For buccal approaches to the
gastro-intestinal and respiratory tracts, sternal or dorsal recumbency with head and neck extended is required. A similar technique can be used for examination of the cloaca, bladder and lower
gastro-intestinal tract. Precise positioning for coelioscopy depends upon the type of reptile, the structure(s) of particular interest, and the preferences of the endoscopist.One of the
great benefits of endoscopy is that when an abnormal structure or pathological lesion is observed, biopsies can be taken under direct visual control. Biopsies can be harvested from the kidneys, gonads,
liver, spleen, pancreas, fat body, lung, gastro-intestinal tract, coelomic membranes and, in general, any abnormal soft tissue structure. CoelioscopyPatient positioning and preparation Dorsoventrally compressed lizards (e.g. Bearded dragons) are usually placed in dorsal recumbency. Laterally compressed lizards (e.g. chameleons) are usually
placed in lateral recumbency. Round-bodied lizards (e.g. Green iguana) can be placed in lateral or dorsal recumbency, but the author prefers lateral placement. Given the relatively small size of most pet
lizards a single mid-coelomic entry point, either in a paramedian or paralumbar area, will usually permit examination of most, if not all, of the coelomic structures. The precise point of entry and position
of the lizard will depend upon the particular organ or system of interest and the preferences of the endoscopist.Chelonia are supported in lateral recumbency with endoscope entry via either of the
prefemoral fossae. Snakes are less commonly subjected to coelomic endoscopy due to the more diffuse fat body and ease of coeliotomy along the entire body length. However, when required, lateral positioning
and entry between the first and second rows of lateral scales enables the scope to enter the coelom just medial to the ribs. Pic01: Green iguana in right lateral recumbency illustrating the
potential endoscope entry area for standard left lateral coelioscopy. Pic02: Left sided coelioscopy in the green iguana – note the two handed support of the camera-sheath-telescope. Pic03: Operating room
set-up and tortoise positioning for standard left prefemoral endoscopy Pic04: The insertion point for coelioscopy in tortoises and turtles is located in the middle of the prefemoral fossa. Coelioscopy of the green iguana
For the purposes of this course, the green iguana will serve as a model for reptile endoscopy (Divers, 1999). A left paralumbar approach is generally preferred, unless physical examination and other
diagnostic tests indicate a right-sided problem. The iguana is positioned in right lateral recumbency, with the left hindlimb taped caudally against the tail base. The entry area is bordered by the ribs,
spine and hindlimb and should be aseptically prepared and draped. The author prefers the use of adhesive clear plastic drapes to permit better visualization of the lizard during anesthesia, insufflation, and
endoscopy. Taking aseptic precautions, a small skin incision is made in the center of the defined area. The skin and underlying muscle is grasped and elevated away from the coelomic viscera and a small pair
of hemostats are gently forced into the coelomic cavity. It is wise to reduce the force of artificial ventilation or temporarily cease ventilating until the scope has been introduced into the coelom, thereby
reducing the possibility of damage to the inflated lung. The hemostats are removed and replaced by the sheath and obturator (with air line attached). By making a small skin and muscle hole, the sheath will
be tight fitting and insufflation gas leakage will be minimal. Once in place the obturator is removed and replaced with the telescope. The coelom is inflated to permit visualization of the internal organs.
Inflation is essential for improving exposure but thought must be given to the adverse effects on lung ventilation and respiration. Various gases can be used for insufflation, but carbon dioxide is
preferred. A variety of specialized gas supplies, filtration units and insufflation devices are available, and a dedicated endoflator is preferred (26012 C). However, an inexpensive aquarium air pump with
controllable air output can be used to good effect in many small reptiles and mammals. Air line tubing is used to connect the insufflation gas supply to one of the ports on the sheath. Gas flow (0.5-1 L/min)
and patient insufflation pressure (3-6 mmHg) are accurately controlled and maintained when using an endoflator. When using an aquarium air pump the second sheath port is left open to avoid over-inflation
(i.e. allows air to continuously escape from the sheath-scope-animal. Occluding this open port with a finger increases insufflation, while lifting the finger off the port decreases insufflation. By careful
finger control, insufflation can be crudely controlled.Once the endoscope has been inserted, it is often necessary to gently touch the tip of the scope against a coelomic membrane to clean the terminal
lens of condensation or tissue fluid. If there is fat or blood on the lens it is usually more effective to remove the telescope from the sheath, clean with damp gauze and then replace. It is important not to
persist with a dirty lens. Poor vision is your enemy that will reduce your endoscopic abilitiy and increase procedural time. Always keep your lens clean. Upon entry into the iguana, the first organ to note
is the large brown liver lying in the mid-ventral coelom. Advancing the scope cranially will reveal the heart at the cranioventral aspect of the coelom, close to the thoracic inlet. Note that there are no
diaphragmatic, post-pulmonary, or longitudinal membranes in the iguana. These membranes do exist to a greater or lesser extent in tegus, monitors, crocodilians, and some chelonians. Minor perforation of
these membranes by the telescope will not cause any harm as long as the lumen of the lung or intestinal tract is not penetrated. Dorsal to the heart and extending from thoracic inlet to mid-coelom are the
paired lungs. Lung ventilation will be substantially reduced during insufflation and careful communication with the anesthetist is required to balance inspiration pressure and insufflation pressure. Caudal
to the lungs, the stomach resides in the mid-coelom, and just dorsocaudal to the stomach, is the spleen – an elongated dark red structure in the iguana. Careful examination between the stomach and spleen,
particularly below the spleen, will reveal the pancreas. The gonads are located just caudal to the spleen close to the dorsal midline. Gender can be determined at a very early age. Dorsal to the gonads are
the adrenal glands lying adjacent to the renal veins. The vas deferens of males and oviducts of females are also visible and can be followed caudally to the pelvic inlet. It is more difficult to examine the
normal kidneys of healthy iguanas because they reside largely within the pelvic canal. However, it is always possible to examine part of the kidney(s) with the endoscope. [Because the kidneys are located
caudal to the skin incision and endoscope entry site, it is necessary for the right hand supporting the camera-sheath-scope to cross over the left hand supporting the end of the sheath-scope. Therefore, if
performing a primarily kidney examination and biopsy, the iguana can be rotated 180 degrees so that the dorsum is facing the endoscopist. In this orientation, the right-handed endoscopist, can examine and
biopsy the kidney without crossing the hands.] Moving ventrally from the pelvic inlet the endoscopist will encounter the bladder and fat body. On the left side, the small and large intestines are apparent.
On the right side, the gall bladder and large colon are usually obvious. In addition, the pancreas is easier to locate on the right side, residing close to the mid-ventral region, just caudal to the liver
and gall bladder, between the duodenal loops. Pic05: Enlarged liver in a green iguana with hepatitis Endoscopic gender identification Rigid endoscopy can also
be utilized as an effective technique for determining the gender of reptiles (Schildger, 1994; Frye, 1996). This technique is extremely useful in some species of lizards such as Blue tongue skinks (Tiliqua
spp.), Prehensile tailed skinks (Corucia zebrata), Monitor lizards (Varanus spp) and Gila monsters and Beaded lizards (Heloderma spp). These lizards can be challenging to sex by other methods. There are
other methods for sexing these lizards that may be less invasive, but they may not be conclusive (e.g. ultrasonography in sexually immature lizards). Rigid endoscopy allows direct visualization of the gonad
to identify the sex but also provides feedback on gonadal activity and or possible gonadal pathology. Additionally with this sexing modality other organs in the coelomic cavity can be inspected at the time
of the procedure to give an overall assessment of the reptile's health status. The technique for endoscopic sexing follows the same approach as is described for Coelioscopy. Generally a lateral recumbency
approach in the paralumbar area allows the best visualization. The paired coelomic fat bodies make it difficult to visualize the gonads from a dorsal recumbency, paramedian approach. The gonads in lizards
are usually located dorsally (along the spine) in the mid-caudal coelomic cavity. They are cranial to the kidneys and adjacent or just caudal to the adrenal glands. Usually the right gonad is cranial to the
left.The testis is usually ovoid and smooth. It may enlarge tremendously during reproductive activity. The immature or inactive ovary generally appears as a small cluster of clear
fluid-filled round follicles. As the ovary matures and becomes active some of the follicles will enlarge dramatically and appear yellow to orange in color as they fill with yolk (vitellogenesis). Some
species of lizards (e.g. monitors, Varanus spp.) have thin post-hepatic and/or post-pulmonary membranes that may be pigmented and obscure the gonads. The membrane can be opened to allow better visualization
by grasping and tearing with retrieval forceps, or incising using the scissors. With practice this endoscopic sexing technique can be safely and quickly accomplished thus providing a valuable and important
service for your reptile clients. Pic06: Male testis (green iguana) Pic07: Female ovary (green iguana) Biopsy & Instrument Use The author uses 3 and 5F
flexible biopsy forceps to harvest tissue samples for histopathology and microbiology. The small sample size permits the taking of several biopsies for multiple laboratory tests, the taking of sequential
biopsies to monitor progress and the use of endoscopic biopsy techniques in patients as small as 100g.The 3 and 5F grasping forceps are useful for manipulating tissues, debridement and
retrieving foreign objects including parasites. The fine aspiration/injection needle can be used for the aspiration of fluid from cystic structures where biopsy may be contraindicated due to post-sampling
leakage. The author has also used the needle instrument for remote aspiration, irrigation and drug administration. Pic08: Endoscopic kidney biopsy in a turtle. Tracheoscopy The 2.7mm telescope within a
exam/protection sheath has an outer diameter of 3.5mm. This is suitable for tracheoscopy in snakes, lizards and chelonians over 4kg. Blockage of the trachea in reptiles for the purposes of endoscopy is well
tolerated by anaesthetized reptiles, and there is no need to provide alternative ventilation (c.f. air sac intubation in birds). For smaller reptiles, smaller diameter telescopes (1.9mm) or semi-rigid
endoscopes (1mm) are available. The unprotected 2.7mm telescope can also be used with extreme caution, making sure that the reptile's head and neck are fully extended and straight. Always use a mouth gag to
guard against a lightly anesthetized reptile from biting down on the scope.
Pic09: Normal trachea in a Boa constrictor snakePic10: Severe granulomatous pneumonia in a Ball python due to Mycobacteria spp. Gastro-Intestinal Endoscopy The telescope-operating sheath
system can be used to examine the oral cavity, esophagus, stomach, cloaca, oviducts, and bladder of many reptiles <3kg. Flexible fiberscopes are required for snakes and larger lizards and chelonians.The use of saline irrigation greatly improves visualization, although gas insufflation is effective for foreign body identification and removal. It is important to dilate the tract when
advancing the scope-sheath system to avoid damage and laceration to the thin intestinal wall. All animals must be intubated to avoid aspiration of irrigation fluids. Pic11: Endoscopic view of
a corn snake's stomach, indicating a tumor that was causing the regurgitation in this animal. |
