Clinical Examination of Reptiles
by
Sharon Redrobe BVetMed BSc MRCVS
The Snake
It is important to obtain a thorough clinical history from the owner.
This should include feeding, weight, ecdysis, faecal and urate production.
The following need to be assessed:
- obtain accurate length (rostrum-cloaca) and weight
- inspect rostrum, nostrils and infra-orbital pits (discharge, occlusion, trauma).
- check eyes clear, inspect spectacles under magnification for abnormalities
- ensure tongue flicking normally and snake moving normally, able to support head etc..
- examine oral cavity (mucous membranes normally clear, but no petechiation, excess salivation,
oedema, fluid from respiratory tract)
- body should be rounded (triangular if emaciated)
- skin elasticity? Check hydration and palpate for swellings
- check scales for haemorrhage, blisters, loss (check ventral scales too)
- check cloaca for oedema, erythema, discharge, swellings
- make faecal smear if faeces produced
- smaller snakes and hatchlings may be transilluminated
Average organ position in boas and pythons
| Organ | Position
(expressed as % of total length rostrum-cloaca) |
|---|
| heart | 22 - 33 |
| lungs | 33 - 45 |
| air sac | 45 - 65 |
| liver | 38 - 56 |
| stomach | 46 - 67 |
| intestines | 68 - 81 |
| right kidney | 69 -7 7 |
| left kidney | 74 - 82 |
| colon and cloaca | 81 - 100 |
| roughly |
cranial 1/3 | oesophagus, trachea, heart |
| middle 1/3 | lungs, liver, stomach, cranial air sac |
| caudal 1/3 | pylorus, duodenum, intestines, kidneys, gonads, fat body,cloaca |
The Lizard
As above where relevant plus:
- check medial temporal joint (orally) for white deposits (= uric acid deposits)
- assess limb strength and locomotion, and bone/soft tissue swelling (see MBD)
- check digits and tips of tail (dry gangrene with dysecdysis)
- smaller lizards e.g. geckos can be transilluminated
- wrap in damp towel to auscultate lungs/heart
- faecal smear if deposited
The Chelonian
As above where relevant plus:
- assess body condition using Jackson's ratio
- check locomotion (does eventually come out of shell when left alone?) and strength
- check shape of shell for evidence of metabolic bone disease, haemorrhage,trauma.
- tympanic membrane should be flat/concave
- beak should be evenly apposed
- inspect mouth, note clear eustachian tubes
Clinical Aspects of Reptile Medicine
Injection Sites
The renal portal venous circulation in reptiles means that injection into the hindlimb musculature may be
eliminated via the kidneys before reaching the rest of the body (however, recent work disputes this; JWD
Jul 95).One should avoid injecting into the tail of those animals that can shed their tails (a process known
as autonomy). These animals include most geckos, the green iguana. Although the tail will regrow, it will
be a different shape and often colour than the original.
It is also embarrassing to explain to the owner!
| i/m | snake | intercostal muscles of body |
| lizard | fore- and hind-leg muscles, tail muscles |
| chelonian | as lizard, plus pectoral muscle mass at angle of forelimb and neck |
| s/c | in loose skin (over ribs in snake/lizard) |
| i/v | see blood sampling veins |
Force Feeding
Give oral fluids e.g. lactated Ringers, Hartmanns, daily equal to 4%- 10% body weight.
Mix up feed at 5g protein and 500kJ/Kg bodyweight daily
e.g. BuildUp (Carnation foods), Protinaid (VetDrug).
1. Snake
Manually restrain animal, open mouth and insert gag e.g. folded piece of radiograph with hole cut into
centre. Hold anterior of snake vertically. Insert well lubricated end of French catheter into oesophagus to
level of stomach. Syringe in fluid.
2. Lizard
The stomach is positioned just behind caudal edge of ribs. Proceed as for snake.
3. Chelonian
The stomach is positioned midway down plastron. Measure stomach tube from caudal end of abdominal s
hield to just beyond gular notch. Hold the chelonian upright, sitting on caudal shields. Extend neck and hold
head behind mandible. The neck must be fully extended to ensure the oesophagus is straightened.
Prise open mouth and insert gag. Insert lubricated, prefilled tube to correct depth and slowly infuse liquid.
Withdraw tube slowly. Take care not to overfill the stomach. If that occurs, you will see food
wellling up into the mouth.
Fluid Therapy
Most sick reptiles will present dehydrated, requiring fluid therapy or force feeding.
Consider these if;
the reptile has continued weight loss,
dehydration (PCV<.25l/l) with an associated hypoglycaemia (blood glucose < 5.2 mmol/l).
Fluids given s/c, i/p or i/v.
Care; as reptiles lack a diaphragm, the administration of large volumes of fluid i/p may impair respiration.
Faecal Examination
Reptiles often deposit urates/faeces when being examined. If not, a colonic wash may be performed as follows:
- insert lubricated French catheter attached to syringe filled with sterile saline into the cloaca and colon
(it should slide in easily with the right size)
- flush in saline and aspirate several times
The following examination techniques may then be used;
- Direct wet mount - dilute small sample with saline and examine under high power (x400) to see
spinning flagellates and static nematode ova
- mix faecal sample with eosin for background staining to show encysted entamoeba
- Gram Stain. Care: Gram negative bacteria are frequently recovered from clinically healthy captive
reptiles. However, most infections are caused by gram negative pathogens e.g. Pseudomonas, Aeromonas, Proteus,
Providentia, Arizona, Salmonella
- examine sediment (following centrifugation) for protozoa and trematode ova
- flotation technique for nematode ova
Care: reptiles may pass prey parasites e.g. mouse nematodes which are
non-pathogenic to the reptile.
Blood Sampling
It is imperative that the maximum blood volume that may be safely withdrawn is accurately calculated as it
is easy to overestimate in small animals. In Reptiles the total blood volume varies with species but is
approximately 5-8% bwt (70 ml/Kg).
Of this, 10%may be the maximum withdrawn safely. Thus a 100g reptile can only have 0.7ml safely taken.
It is obviously important that the reptile patient is weighed accurately and the calculations made before
blood is withdrawn!
Collect blood into lithium heparin tubes (EDTA tends to lyse cells)
Blood Sampling Sites
1. Snake
The palatine vein, ventral tail vein, or cardiocentesis
a). ventral vein The only method not requiring sedation, - identify
cloaca, insert needle distal to this, into tail at midline at 450 angle,
advance to vertebrae, aspirate as slowly withdraw.
b). cardiocentesis requires sedation. Palpate/ visualise beating heart,
stabilise with finger and thumb. Use 23/25G needle on 3-6ml syringe.
Slide needle under ventral scale and aspirate syringe. If only clear
fluid is withdrawn, this is pericardial fluid.
2. Lizard
large animals - ventral tail vein
smaller lizards- clip toe nail and collect blood with capillary tube.
3. Chelonian
The following sites may be used:
cardiocentesis,jugular vein,brachial vein, ventral coccygeal vein,
orbital sinus and toe nail clipping.
Atempts to venepuncture limb veins often results in collection of lymph
only, as these vessels are large and the veins cannot be visualised.
Collection from a jugular vein; hold animal between your knees and extend
the neck towards you. the jugular vein will be seen as a bulge between
the tympanic membrane and the base of the neck. Swab the site with 70%
ethanol. Insert 23/25G butterfly catheter.
In Mediterranean tortoises, the dorsal tail vein is the most convenient
site for venepuncture
Haematology
Measure number RBC, WBC, differential WBC count, PCV,and the
haemoglobin concentration.
Biochemistry
Use plasma (gain greater volume from blood sample and serum tends to clot). Take blood sample and
centrifuge immediately, remove plasma.
Measure Na, Cl, Ca, P, Gl, urea, uric acid, creatinine, cholesterol, AST, ALT, ALP, total protein.
Blood Smear
The following may be carried out:
Differential WCC, morphology of cells, level of toxic changes, inclusion bodies, blood parasites, bacteria
Radiography
Positioning is important when radiographing reptiles.
Animals can be taped down, radiographed through a box or bag if not sedated.
Assess organ position, shape, size, density and homogeneity.
Check state of reptile nutrition; skeletal density, gastrointestinal organs and contents.
Snake
Radiograph regions of suspected lesion only. If radiographing whole snake, take sequential sections along
length of snake using lead markers every 10 - 20 cm.
WHOLE BODY COILED RADIOGRAPHS ARE ALMOST USELESS
Barium Meal :
Studies can be performed as follows;
A 2Kg snake requires 10ml barium sulphate suspension by
oesophageal tube followed by 90ml air for double contrast study. 15mins
later youshould see oesophageal folds, gastric rugae, pyloric sphincter
and duodenal villi. 5mg metoclopramide reduces the GIT food transit
time from days to 12 hours.
Lizard
Poor skeletal density most common finding, if suspected, reduce the kV.
Normal lizards show similar bone/soft tissue contrast to mammals.
Dorso-ventral and lateralviews as mammalian positioning.
Chelonian
DV View; care; healthy animal can move very quickly off the table!
Take exposure between expiration and inspiration. Placing animal on a
raised column with the feet off the table to aid restraint
Lateral -tilting chelonians onto their side distorts the diaphragm and
lungs, thus horizontal beam required; centre beam on 6-7th marginal
shield at right angles to vertebral column
cranio-caudal view is useful for contrasting two lung fields. Centre
horizontal beam on nuchal shieldhead, neck, limbs
General anaesthesia required for optimal positioning of extremities
Barium meal :
2ml barium sulphate by stomach tube followed by 18ml air for double contrast studies in animals 1Kg
Ultrasonography
Lizards and Snake
7.5 and 10MHz transducers with stand-off for suitable
resolution in small reptiles. 5 and 3.5 MHz transducers for larger
reptiles ,linear array transducers are used to view the internal organs
via the ventral body wall using an aqueous gel.
Chelonian
The only sites available for the access of ultrasound are the soft
tissue areas known as the femoral fossa (cranial to the hind limb)
and the cervical fossa (at the base of the neck).
Sharon Pickavance BVetMed BSc MRCVS
NVS / Exotic Species Vet
Small Animal Clinic
Edinburgh University
Edinburgh
EH9 1QH
UK
Phone: +44 (0)131 650 6074
Fax : +44 (0)131 650 6577
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Received November 1996
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