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Diagnostic aids that are used routinely with more familiar domestic animals are also applicable to snakes. Those commonly available in veterinary practice include faecal examination, microbiology, cytology, haematology and biochemistry, radiography and biopsy.  This section will cover specimen collection and interpretation.

Diagnostic aids that are used routinely with more familiar domestic animals are also applicable to lizards and snakes. Those commonly available in veterinary practice include faecal examination, microbiology, cytology, haematology and biochemistry, radiography and biopsy.  This section will cover specimen collection and interpretation.

[[Image:Culture_copy.jpg|250px|thumb|right|©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]

[[Image:Culture_copy.jpg|250px|thumb|right|©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]

==Colonic wash==

==Colonic wash==

A lubricated catheter with an attached syringe is gently inserted through the vent. The catheter should pass easily into the colon and if resistance is met it is pushing against the dorsal wall of the cloaca. Up to approximately 10ml/kg of sterile saline is injected into the colon. The fluid is massaged prior to aspiration.

A lubricated catheter with an attached syringe is gently inserted through the vent. The catheter should pass easily into the colon and if resistance is met it is pushing against the dorsal wall of the cloaca. Up to approximately 10ml/kg of sterile saline is injected into the colon. The fluid is massaged prior to aspiration.

==Faecal evaluation==

==Faecal evaluation==

Evaluation of the faeces is considered part of a minimum database for snakes. Faeces can be obtained by the collection of normally voided faeces, bathing to stimulate defecation, the gentle insertion of a cotton-tipped applicator or colonic wash. The faecal sample for evaluation should be as fresh as possible. The following examinations can be conducted on the faeces.

Evaluation of the faeces for protozoa, amoeba and nematodes is considered part of a minimum database for lizards. Most reptiles defecate infrequently, especially if they have been ill and anorexic. Faeces can be obtained by i) collection of normally voided faeces, ii) bathing to stimulate defecation and iii) colonic wash. (The rectum is quite distensible. A lubricated large gauge tube is inserted into the colon through the vent and approximately 10 ml/kg of sterile water is injected into the colon. The fluid is massaged prior to aspiration.)

*Wet mount

The sediment can be examined after a faecal sample is centrifuged.

===Wet mount===

*Faecal sedimentation

*Special staining

*Water preparation - nematode ova and moving flagellates (concentrated saline may destroy flagellates immediately) iodine stain (e.g. Lugol's) or eosin - identification of encysted entamoeba.

*Gram stain - Though they are frequently recovered from clinically healthy captive reptiles, most pathogenic infections are caused by Gram negative pathogens e.g. Pseudomonas, Aeromonas, Proteus, Salmonella.

*Other tests, as necessary, such as presence of faecal haemoglobin and digestive enzymes

The faecal material is mixed with the high specific gravity flotation fluid. The debris is removed with a filter and material that is less dense than the flotation fluid, such as nematode ova, will rise to the top. This can then be examined on a microscope slide.

==Urinalysis==

==Urinalysis==

Urinalysis is not a useful diagnostic aid in snakes since contamination and modification of the urine occurs in the cloaca and colon.

Urinalysis is not a useful diagnostic aid in reptiles since contamination and modification of the urine occurs in the cloaca and colon.

==Urate examination==

==Urate examination==

It is worthwhile examining the urates for unusual pigmentation. Urates stained with bile pigments have been associated with liver disease. Green-stained urates can be mixed with saline and coverslipped for microscopic examination. This may reveal amoebic cysts or operculated fluke ova.

It is worthwhile examining the urates for unusual pigmentation. Urates stained with bile pigments have been associated with liver disease. Green-stained urates can be mixed with saline and coverslipped for microscopic examination. This may reveal amoebic cysts or operculated fluke ova.

*''Tissue containing bone'' - Tissues containing bone should be formalin-fixed then treated with a decalcifying solution.

*''Tissue containing bone'' - Tissues containing bone should be formalin-fixed then treated with a decalcifying solution.

*''Tissue for virus isolation'' - For viral isolation, place tissue sections in individual sterile bags and freeze.

*''Tissue for virus isolation'' - For viral isolation, place tissue sections in individual sterile bags and freeze.

==Swab==

==Swab==

Culture sites should be vigorously sampled. Culture blood if septicaemia is suspected. Swabs for bacteriology should immediately go into transport media if there is any delay in culturing. It is preferable to incubate at 25°C and 37°C. It is advisable to take a second swab and roll this onto a microscope slide for gram staining. Culturing of fluid within the oral cavity usually gives non-diagnostic results. Preferable methods, as appropriate, are biopsy of oral lesions, sampling high within the choanal slit or tracheal sampling (by passing a microswab through the glottis).

Culture sites should be vigorously sampled. Culture blood if septicaemia is suspected. Swabs for bacteriology should immediately go into transport media if there is any delay in culturing. It is preferable to incubate at 25°C and 37°C. It is advisable to take a second swab and roll this onto a microscope slide for gram staining. Culturing of fluid within the oral cavity usually gives non-diagnostic results. Preferable methods, as appropriate, are biopsy of oral lesions, sampling high within the choanal slit or tracheal sampling (by passing a microswab through the glottis).

==Transtracheal wash==

==Transtracheal wash==

Respiratory disease is common in snakes and sample collection from the respiratory tract may be essential for diagnosis and treatment. Transtracheal washes should therefore be a routine procedure for all snakes with respiratory disease. They may be collected in physically restrained snakes but chemical restraint is usually required.  

Respiratory disease is common in reptiles and sample collection from the respiratory tract may be essential for diagnosis and treatment. Transtracheal washes should therefore be a routine procedure for all lizards and snakes with respiratory disease. They may be collected in physically restrained snakes but chemical restraint is usually required.  

[[Image:Glottis.jpg|250px|thumb|right|©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]

[[Image:Glottis.jpg|250px|thumb|right|©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]

*Collection - The snake is positioned with the head slightly elevated. Identify the position of the heart. The jaws are opened and the glottis identified. Upon inspiration a sterile catheter is introduced to the appropriate level. The lung field is caudal to the heart in boids and colubrids. Sterile saline equal to 0.5-1% bodyweight is injected. The head is then lowered and the fluid aspirated. Occasionally more is aspirated than injected and this usually indicates respiratory disease. Any fluid left in the lungs is absorbed.  Use of endoscopy allows visualisation as well as sampling. Samples of low cellularity can be concentrated using centrifugation.

*Collection

The patient is positioned with the head slightly elevated. Identify the position of the heart. The jaws are opened and the glottis identified. Upon inspiration a sterile catheter is introduced to the appropriate level. The lung field is caudal to the heart in boids and colubrids. Sterile saline equal to 0.5-1% bodyweight is injected. The head is then lowered and the fluid aspirated. Occasionally more is aspirated than injected and this usually indicates respiratory disease. Any fluid left in the lungs is absorbed.  Use of endoscopy allows visualisation as well as sampling. Samples of low cellularity can be concentrated using centrifugation.

*Evaluation - The sample can be used for:  

*Evaluation - The sample can be used for:  

**A wet mount for microscopy for parasite

**A wet mount for microscopy for parasite

Stomach washings can be obtained for preparation of wet mounts, cytology and microbiology. A lubricated catheter is introduced into the stomach via the oesophagus and sterile saline is injected. The stomach is massaged and the fluid is then withdrawn. The specimen can be concentrated by centifuging. Gastric lavage is commonly used in the diagnosis of cryptosporidiosis.

Stomach washings can be obtained for preparation of wet mounts, cytology and microbiology. A lubricated catheter is introduced into the stomach via the oesophagus and sterile saline is injected. The stomach is massaged and the fluid is then withdrawn. The specimen can be concentrated by centifuging. Gastric lavage is commonly used in the diagnosis of cryptosporidiosis.

[[Image:Spinal_needle.jpg|250px|thumb|right|'''Spinal needle used for bone marrow sampling''' - ©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]

[[Image:Spinal_needle.jpg|250px|thumb|right|'''Spinal needle used for bone marrow sampling''' - ©RVC and its licensors, Peer Zwart and Fredric Frye. All rights reserved]]

[[Category:Lizard and Snake Diagnostics]]

[[Category:Lizard and Snake Diagnostics]]