Clinical Examination of ReptilesbySharon Redrobe BVetMed BSc MRCVSThe SnakeIt 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:
The LizardAs above where relevant plus:
The ChelonianAs above where relevant plus:
Clinical Aspects of Reptile MedicineInjection SitesThe 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!
Force FeedingGive 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. SnakeManually 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. LizardThe stomach is positioned just behind caudal edge of ribs. Proceed as for snake.3. ChelonianThe 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 TherapyMost 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 ExaminationReptiles often deposit urates/faeces when being examined. If not, a colonic wash may be performed as follows:
Blood SamplingIt 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 Sites1. SnakeThe palatine vein, ventral tail vein, or cardiocentesisa). 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. Lizardlarge animals - ventral tail veinsmaller lizards- clip toe nail and collect blood with capillary tube. 3. ChelonianThe 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 HaematologyMeasure number RBC, WBC, differential WBC count, PCV,and the haemoglobin concentration.BiochemistryUse 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 SmearThe following may be carried out:Differential WCC, morphology of cells, level of toxic changes, inclusion bodies, blood parasites, bacteria RadiographyPositioning 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. SnakeRadiograph 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. LizardPoor 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.ChelonianDV 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 1KgUltrasonographyLizards and Snake7.5 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.ChelonianThe 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).
| ||||||||||||||||||||||||||||||||||||||||