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British Veterinary Zoological Sociey Proceedings November 2008 BACK-TO-BASICS The Reptile Consult Simon J Girling [email protected] Initial Assessment An initial assessment should be made of the reptile patient before it is removed from its carry cage/box. This should focus on the following points: 1) Is it potentially hazardous/dangerous to the handler? (e.g. male green iguanas, snapping turtles, aggressive snakes and unlikely but possibly venomous) 2) Is it mouth breathing and therefore in possible respiratory distress? 3) Is it a fragile species? (many geckos will shed their tails very easily, as will many iguanas) 4) Is it suffering from metabolic bone disease making it a risk to handle? (deformed limbs, shell, spine etc and inability to support its own weight in a lizard or chelonian may suggest this condition is present) 5) Is there any evidence of hypocalcaemic tremors/collapse? 6) How large is the animal? (many larger species of tortoise are surprisingly heavy and strong, and snakes longer than 3-4 feet require more than one handler to avoid damaging the patient and putting the handlers at risk). Whilst examining the patient from a distance to ascertain if it is safe to handle, it is a good idea to question the owner about the husbandry of the reptile at home i.e.: 1) 2) 3) 4) What do they feed it? Do they feed vitamin/mineral supplements? Are these supplements dusting powders or fed to prey first (if relevant)? Is there a UV lamp? (may not be necessary for most snakes but is necessary for most lizards and chelonians) 5) Is the UV lamp suitable and is it close enough to the reptile? 6) What temperature range do they keep the vivarium at? 7) What hides/cage furniture is present in the tank? 8) What humidity do they keep the vivarium at? 9) What is the size of the vivarium? 10) How do they provide water and food? (e.g. do they provide water as droplets via a drip set/misting for chameleons etc. or are they inappropriately providing a bowl of water?). 11) Do they have any other reptiles/pets and do these have access? 12) How often do they handle the reptile? (over-handling is a common cause of anorexia in some species of snake). 13) If a snake-when did it last shed it’s skin, and was it a complete shed? 14) When was the last time faeces/urine was passed? 15) When was the last time the reptile was observed eating? Detailed Examination Manual Restraint Snakes The snake family includes Boa Constrictors, Corn Snakes, Burmese Pythons, and Garter Snakes. There are a wide range of sizes from the Anacondas and Burmese Pythons which may achieve lengths of up to 30 feet or more, down to the Thread Snake family which may be a few tens of centimetres long. They are all characterised by their elongated form with an absence of limbs. The danger areas are their teeth (and in the case of the more poisonous species such as the viper family - 57 - British Veterinary Zoological Sociey Proceedings November 2008 their fang teeth), and in the case of the constrictor and python family their ability to asphyxiate their prey by winding themselves around the victim’s chest/neck. With this in mind, the following restraint techniques may be employed. Non-venomous snakes can be restrained by initially controlling the head. This is done by placing the thumb over the occiput and curling the fingers under the chin. Reptiles, like birds have only the one occipital condyle so the importance of stabilising the neck occipital/atlantal joint cannot be underestimated. It is also important to support the rest of the snake’s body, so that not all of the weight of the snake is suspended from the head. This is best achieved by allowing the smaller species to coil around the handler’s arm, so the snake is supporting itself. In the larger species (longer than 10 feet) it is necessary to support the body length at regular intervals, so you will need the help of several people. Indeed it is vital to adopt a safe operating practice with the larger constricting species of snake. For this reason a ‘buddy system’ as with scuba diving, should be operated whereby any snake longer than 5-6 feet in length should only be handled by two or more people. This is to ensure that if the snake was to enwrap the handler, his/her assistant could un-entangle him/her by unwinding from the tail end first. Above all it is important not to grip the snake too hard as this will cause bruising and the release of myoglobin from muscle cells which will lodge in the kidneys, causing damage to the filtration membranes. Poisonous snakes (such as the viper family, Rattlesnakes etc.) or very aggressive species (such as Anacondas, Reticulated and Rock Pythons) may be restrained initially using snake hooks. These are 1 ½ - 2 foot steel rods with a blunt shepherds hook on the end and are used to loop under the body of a snake to move it at arms length into a container. The hook may also be used to trap the head flat with the floor before grasping it with the hand. Once the head is controlled safely the snake is rendered harmless unless it is a member of the spitting cobra family. Fortunately you are unlikely to come across these in general practice, but if you do you must wear plastic goggles, or a plastic face visor as they spit poison into the prey/assailant’s eyes and mucus membranes causing blindness and paralysis. Lizards These include Geckos, Iguanas, Chameleons, Monitors and Agamas. Lizards come in many different shapes and sizes from the four foot long adult Green Iguana to the 4-5 inch long Green Anole. They have roughly all the same structural format with 4 limbs (although these may become vestigial in the case of the slow worm for example) and a tail. Their main danger areas therefore include their claws and teeth, and in some species such as Iguanas, their tails which can lash out in a whip-like fashion. Geckos other than Tokay Geckos are generally docile as are lizards such as Bearded Dragons. Others such as Green Iguanas may be extremely aggressive, particularly sexually mature males. They may also be more aggressive towards female owners and handlers as they are able to detect pheromones secreted during the menstrual cycle. Restraint is best performed by grasping the pectoral girdle with one hand from the dorsal aspect, so controlling one forelimb with forefinger and the thumb and the other between middle and fourth finger. The other hand is used to grasp the pelvic girdle from the dorsal aspect, controlling one limb with the thumb and forefinger, the other again between middle and fourth finger. You may then hold the lizard in a vertical manner with head uppermost to put the tail out of harms way underneath the handler’s arm. If you are holding a lizard in this way, the handler should allow some flexibility as the lizard may wriggle, and overly rigid restraint could damage the spine. It is then possible to present the head and feet of the lizard away from the handler to avoid injury. Some of the more aggressive Iguanas may need to be pinned down, prior to this method of handling. Here, as with avian patients, the use of a thick towel to control the tail and claws is often very useful. In some instances, gauntlets are necessary for particularly aggressive large lizards, and for those which may have a poisonous bite (the Gila Monster and the Beaded Lizard). It is important to assure that you do not use too much force - 58 - British Veterinary Zoological Sociey Proceedings November 2008 when restraining the lizard, as those with skeletal problems such as metabolic bone disease, may be seriously injured. In addition lizards, like other reptiles, do not have a diaphragm and so over-zealous restraint will lead to the digestive system pushing onto the lungs and increasing inspiratory effort. Geckos can be extremely fragile and the Day Geckos for example are best examined in a clear plastic container rather than physically restraining them. Other Geckos have easily damaged skin and so you should use latex gloves and soft cloths and cup them in the hand rather than physically restraining them. Small lizards may have their heads controlled between the index finger and thumb to prevent biting. It is important that lizards are never restrained by their tails. Many will shed their tails at this time, but not all of them will re-grow. Green Iguanas for example will only re-grow their tails as juveniles (less than 2 ½ - 3 years of age). Once they are older than this, they will be left tail-less. Vago-Vagal Reflex This involves closing the eyelids and placing firm but gentle digital pressure onto both eyeballs. This stimulates the parasympathetic autonomic nervous system which, as you know, results in a reduction in heart rate, blood pressure and respiration rate. Providing there are no loud noises or environmental stimulation, after 1 - 2 minutes the lizard may be placed on its side, front, back etc allowing radiography to be performed without using physical or chemical restraint. A loud noise or physical stimulation will immediately revert the lizard to its normal wakeful state. Chelonia This includes all land tortoises (which the Americans refer to as turtles), terrapins and aquatic turtles. Size differences in this order are not as great as for the other two families, but it is still possible to see chelonia varying from the small Egyptian tortoises weighing a few hundred grams all the way up to adult Leopard tortoises at 40 kg, and the Galapogean tortoise family which can weigh several hundred kilograms. The majority of chelonia are harmless, although surprisingly strong. The exceptions include the Snapping Turtle and the Alligator Snapping Turtle, both of which can give a serious bite. Most of the soft-shelled terrapins have mobile necks and can also bite. Even Red Eared Terrapins may give a nasty nip! Restraint can be achieved as follows. For the mild-tempered Mediterranean species, the tortoise may be held with both hands, one on either side of the main part of the shell behind the front legs. For examination, to keep the tortoise still he/she may be placed onto a cylinder/stack of tins which ensure that his/her legs are raised clear of the table, balancing on the centre of the underside of the shell (plastron). For aggressive species it is essential that you hold the shell on both sides behind and above the rear legs to avoid being bitten. In order to examine the head region in these species it is necessary to chemically restrain them. For the soft shelled and aquatic species, soft cloths and latex gloves may have to be used in order not to mark the shell. You should bear in mind that many species of reptile and chelonia have a normal bacterial flora in their digestive systems which frequently includes species such as the Salmonella family. These bacteria are found in abundance all over the body of the reptile. Personal hygiene is therefore very important when handling these patients to prevent zoonotic diseases. Chemical Restraint Many species such as snakes and lizards may be induced via a face mask or induction chamber using 3 – 4 % isoflurane in 100 % oxygen. Chelonia however will breath-hold for hours and so it is - 59 - British Veterinary Zoological Sociey Proceedings November 2008 not possible to induce them by this means. Indeed some lizards may also fight and a quicker form of induction can be achieved by using either: • 5 - 10 mg/kg propofol IV/intraosseously (all reptiles) Or • 2 mg/kg aflxalone (Alfaxan®) IV (all reptiles particularly chelonia) Or • 5 - 10 mg/kg ketamine IM +/- 0.1mg/kg medetomidine (all reptiles) Then intubate and maintain on either oxygen alone, or if not anaesthetised enough add 1 – 2 % isoflurane and IPPV at 4-6 breaths a minute (most reptiles will not breath during anaesthesia for themselves so bagging them or investing in a ventilator is essential for GAs). Examination 1) Weigh the reptile and compare this with any previous data. For certain Testudo spp. it may be possible to use so-called ‘Jackson’s graph/ratio’ to ascertain if the plastral length versus weight is correct. 2) An intra-oral examination using a mouth gag or a pen/pencil to encourage the reptile to open its mouth (be careful with chelonia as they have powerful jaws). This should allow a close examination of the tongue, the roof of the mouth/nasal passages (there is no hard palate in reptiles other than crocodylia). The teeth should be examined, particularly in lizards where acrodont dentition of Agamids is commonly associated with periodontal disease. 3) The glottis may also be visualised at the base of the tongue. Abnormalities such as a discharge from the nasal passages, petechiae or haemorrhages in the mouth, an abnormal or foul odour, and evidence of white or yellow plaques on the mucosa should all be noted and if possible sampled with a swab dampened with sterile water. 4) The tongue should be carefully examined for evidence of infection and trauma, although in some species such as chameleons, it may be impossible to examine the tongue without anaesthetising them. Note that many lizards have a two-coloured tongue e.g. the green iguana has a bright red tongue tip and a pale pink body to the fleshy tongue. 5) A detailed examination of the nares and the eyes. This will allow assessment of any upper respiratory tract disease. Clinical signs of this include: abnormal shaped nare(s); sinking of the globe of the eye; swelling below the globe of the eye (the region of the infraorbital sinus); discharge from the eye itself; swelling of the conjunctiva; corneal blemishes and in the case of snakes, evidence of a retained spectacle. 6) A detailed examination of the skin/shell. This may allow you to see areas of retained slough (snakes should shed in one complete go; lizards in small patches and chelonians only in small patches from the limbs and head/neck/tail). It will also allow any petechiae or ecchymoses to be observed which may indicate septicaemia. Abscesses appear as firm, inspissated subcutaneous masses. 7) A detailed auscultation of the lungs and air sacs. The lungs are best auscultated from the dorsum in Chelonia and lizards. To improve sound conductivity a damp towel/cloth may be placed over the reptile and the diaphragm of the stethoscope applied to this. Snakes are difficult to auscultate owing to their long thin lungs. 8) The heart is very difficult to auscultate and it is often preferable to use a Doppler probe to assess blood flow through/out of the heart to determine heart rate. Note that heart rate and sounds for reptiles are significantly different from mammals owing to the three-chambered - 60 - British Veterinary Zoological Sociey Proceedings November 2008 heart (one ventricle and two atria) and its different construction. In addition, environmental temperatures will significantly alter heart rates. Heart positions vary widely between species. In snakes it is often located at the caudal end of the first third of the snake. In lizards such as Iguanids and many Agamids, the heart is cranially situated within the pectoral girdle. In monitor lizards and heloderms it is located more caudally. In chelonians the heart is usually midline immediately behind the base of the neck. 9) A detailed examination of the limbs may be made. Palpate the long bones, as metabolic bone disease is common, producing fibrous dystrophy where the poorly ossified bone swells due to cartilage deposition making the limb look fat and muscular. Palpation reveals however that it is merely bone mass and not muscle. Shells of chelonia may be deformed and soft to touch. Mandibles of lizards may be bowed and malleable with this condition as well. 10) A detailed examination of the vent and caudal coelom should also be made. Many lizards have kidneys tucked into the pelvic area and so these should not be palpatable from in front of the ilial wings in a normal animal. 11) Snakes may be palpated by running a finger along the ventrum to feel for masses or obstructions. Chelonia are obviously difficult to palpate, although gentle ballotment of eggs or masses by placing a finger cranial to a hind limb and rolling the animal onto its side and away again is possible. 12) Determining the sex of a reptile is also important. Species variation is great, but there are some broad principles. See table 1. Table 1: Sex determination in reptiles Species group Male Often smaller (e.g.. red eared Chelonians terrapins, Testudo spp.) although some are larger (Geochelone sulcata) Female Often larger than males (with exceptions noted) Longer forelimb claws (red eared terrapins) Lizards Dished plastron (many Testudo spp.) Flat plastron, my be hinged (Testudo graeca) Longer tails Shorter tails Red iris colour (eastern box turtle) Greater ornamentation (e.g. horns in Jackson’s chameleon) and colouration. Brown iris colour (eastern box turtle) Often less coloured, lack of prominent dewflaps etc. V-shaped arrangement of pre-vent pores (geckos) No pre-vent pores Prefemoral pores on underside of thighs. Monitors and some heloderms have mineralised hemipenes detectable radiologically - 61 - No pre-femoral pores British Veterinary Zoological Sociey Proceedings November 2008 Snakes Longer tails Shorter tails Probing of hemipenes can be performed to a depth >6/8 ventral scales depth. Scent glands in this region in females allow probing to a depth of 2-6 ventral scales Emergency Stabilisation of a Collapsed Reptile Patient Fluid types used in reptile and amphibian practice Dehydration in reptiles has been quoted as being either due to: ► ► ► rapid water loss alone, such as occurs with acute diarrhoea, thermal burns or vomiting, in which case the remaining extracellular fluid (ECF) becomes reduced, but is still the same composition i.e. isotonic or long-term anorexia, producing a reduction in electrolytes and creating a hypotonic ECF water deprivation or oral trauma preventing drinking will lead to increases in the tonicity of the ECF, and create a hypertonic dehydration. Lactated Ringer’s/Hartmanns As with cats and dogs, this form of fluid is useful as a general-purpose rehydration/maintenance fluid. It is particularly useful for reptiles suffering from metabolic acidosis such as those described above with chronic gastro-intestinal problems but can also be used for fluid therapy after routine surgical procedures. Glucose/Saline Combinations These are useful for reptiles and amphibians as they may have been through periods of anorexia prior to treatment, and therefore may well be borderline hypoglycaemic. In addition for reptiles with renal disease and elevated potassium levels these fluids are the fluid types of choice. There is some evidence that in reptiles, and probably amphibians, the isotonicity of the extracellular fluids is lower than that seen in mammals. Studies on non-marine reptiles suggest that isotonicity for the majority of reptiles is 0.8 % rather than the 0.9 % assumed for mammals. To this end a number of fluid combinations utilising the above two types of crystalloid support have been derived as follows. a) One third 5 % glucose with 0.9 % saline; one third lactated Ringer’s solution; one third sterile water. b) Nine parts 5 % glucose with 0.9 % saline to 1 part sterile water. Many texts, though, still advise that straightforward undiluted lactated Ringer’s solution or 4 % glucose with 0.18 % saline may be used. It is of course important that the fluids administered be warmed to the reptile/amphibian’s preferred body temperature (approximately 30 - 35˚C) before being given. Protein amino acid/B vitamin supplements These are useful for nutritional support by using versions such as Duphalyte® (Fort Dodge) at the rate of 1 ml/kg body weight/day. They are particularly good in cases where the patient is malnourished or has been suffering from a protein losing enteropathy such as cases of heavy parasitism or a protein losing nephropathy to help replace some of the compounds needed for - 62 - British Veterinary Zoological Sociey Proceedings November 2008 replenishment. It is also a useful supplement for patients with hepatic disease or severe exudative skin diseases such as heater burns. Colloidal Fluids These have been used in reptilian practice when direct venous access has been achievable, and there is some evidence that they may be used via the intraosseous route. Their usage is, as with cats and dogs, for when a serious loss of blood occurs, in order to support central blood pressure. This may be a temporary measure whilst a blood donor is selected, or if none is available, the only means of attempting to support such a patient. Oral fluids/electrolytes These may also be used in reptile and amphibian practice for those patients experiencing mild dehydration, and for ‘home’ administration. Many products are available for cats and dogs, and may be used for reptiles, but as with the crystalloid fluids, it is advisable to over-dilute these oral electrolytes by approximately 10 % otherwise their concentration will be greater than the reptile’s ECF and so water will move from the body into the GI tract. One electrolyte in particular may be useful and that is Avipro® by VetArk. This is a probiotic, but used at the correct concentration may also be used as an oral electrolyte solution. The lyophilised bacteria are useful to aid digestion, which is also often upset during periods of dehydration. Calculation of Fluid Requirements for Reptiles These may be calculated as for cats and dogs. It is worth noting that a lot of the fluid intakes are normally consumed as ‘food’ i.e. in the form of fresh vegetation for herbivorous species. This is difficult to take into consideration, and therefore is safer to assume that the debilitated reptile will not be eating significant enough amounts for this to matter in the calculation. Levels of fluid replacement rates have received relatively little research. Consequently for the vast number of reptiles and amphibians a calculated guess has to be made! Frye (1991) recommends that levels of 20 - 25 ml/kg body weight per day be used for hydration purposes in both reptiles and amphibians, and current literature suggests that rates across several species vary from 10 - 50 ml/kg/day. There is however another restriction to fluid rates of administration. That is that most fluids are given intracoelomically in the debilitated reptile, although intravenous and intraosseous routes may also be utilised. Reptiles do not possess true diaphragms, and as such the thorax and abdomen are all interconnected as a common cavity or ‘coelom’. When fluids are placed in this cavity it is equivalent to giving intra-peritoneal fluids in a mammal, but as there is no diaphragm these fluids can cause pressure to build-up on the lungs. Excessive fluids may severely compromise respiration. Excessive fluids may also: ► ► ► ► overload the circulation create pulmonary oedema result in cardiac and renal over perfusion cause solute wash-out, with potassium in particular being excreted with the increased diuresis causing hypokalaemic crisis to develop. This may manifest initially as an anorectic reptile, but will progress to cardiac arrhythmias, coma and death. As with cats and dogs, it is possible to assume that 1 % dehydration equates with needing to supply 10 ml per kilogram body weight fluid replacement in addition to the maintenance requirements. It is also possible to make some qualitative assessment of the level of dehydration from the elasticity of the skin, although reptile skin is not as elastic as mammalian, it still should be freely mobile and recoil, albeit slowly after tenting. Other factors to assess are the brightness of the corneas in species with - 63 - British Veterinary Zoological Sociey Proceedings November 2008 mobile eyelids. In those without mobile eyelids (e.g. snakes) the collapse of the spectacle (the clear fused eyelids) is suggestive of dehydration. Other assessments of thirst and urate output can be made over 24 hours. Assumptions then have to be made on the degree of dehydration of the reptile concerned. Roughly we have: 3 % dehydrated – increased thirst, slight lethargy, decreased urates. 7 % dehydrated – increased thirst leading to anorexia, dullness, tenting of the skin and slow return to normal, ‘dull corneas’, loss of turgor of spectacles in snakes. 10 % dehydrated – dull - comatose, skin remains tented after pinching, desiccating mucous membranes, sunken eyeballs, no urate/urine output The alternative is to compare packed cell volumes and total protein levels to assess dehydration, again with 1 % increase in PCV suggesting 10 ml/kg fluid replacements are needed. Species Green iguana iguana) PCV l/l Total Protein g/l (Iguana 0.25-0.38 28-69 Testudo spp. Tortoise 0.19-0.4 32-50 Ratsnake (Elaphe spp.) 0.2-0.3 30-60 Boa constrictor constrictor) 0.2-0.32 46-60 (Boa Table 2: packed cell volumes (PCV) and total protein ranges for selected reptiles In working out the fluid deficits, it is still important not to exceed 25 - 30 ml/kg/day for reasons mentioned above. Therefore rehydration of severely debilitated reptiles may take days to weeks. As with avian patients therefore the fluid deficit may need to be split over several days. Blood Transfusions These are indicated when the PCV has dropped below 0.05 l/l, and they may be given via intravenous or intraosseous routes. Cross-matching of blood groups does not appear to be necessary for one-off transfusions, but the same species should be attempted each time, i.e. green iguana to green iguana, boa constrictor to boa constrictor. However in a dire emergency it is possible to transfuse any one of a family group with another from the same group i.e. iguanid to iguanid and boiid to boiid. Up to 2 % body weight as blood may be taken from healthy species, preferably into a pre-heparinised syringe before immediately transfusing into the recipient. Access routes available for fluid administration in reptiles Access routes for snakes Oral This is not such a good route for seriously debilitated animals but useful for those with pharyngostomy feeding tubes in place, or if the owner/handler is experienced in stomach tubing hence it may be useful for mild cases of dehydration where owners wish to home-treat their pet. A stomach tube is easily passed by restraining the snake’s head gently but firmly and then inserting a plastic/wooden tongue depressor to open the mouth. A lubricated feeding tube is then passed through the labial notch (the area at the most rostral aspect of the mouth without teeth) and down to a distance of one third of the snake’s length. This route, though, is restricted in its use for severely dehydrated - 64 - British Veterinary Zoological Sociey Proceedings November 2008 animals, and those with pre-existing gut pathology due to poor rates of fluid uptake from the gut in these individuals. Subcutaneous The lateral aspect of the dorsum of the snake in the caudal third of its body is the ideal site. This is a good technique for use as routine post-operative administration of fluids for longer recovery patients undergoing minor surgical procedures such as skin mass removals. If positioned correctly, there is a lymph sinus which runs just lateral to the epaxial muscles on either side, just subcutaneously which can be used for moderately large volumes. It may however still be necessary to use several sites. Intracoelomic This route is especially good from more seriously dehydrated reptiles, as there is a larger vasculature at this site from absorption. The needle or butterfly catheter is inserted 2 rows of lateral scales dorsal to the ventral scales in the caudal third of the snake, but cranial to the vent. The needle is inserted so that it just penetrates the body wall, the plunger of the syringe is pulled back to ensure no organ puncture has occurred and the fluids administered. If correctly inserted there will be no resistance to the injection. Intravenous There are no major vessels for this technique in snakes that are easily accessible. Therefore if an intravenous route is to be used one of the following routes is required: • The ventral tail vein – this is more of a plexus of veins, and may be accessed from the ventrum. The needle is inserted midline, one third of the tail length from the vent, and advanced until it touches the coccygeal vertebrae at a 90 degree angle. The needle is then retracted slightly whilst applying negative pressure to the syringe until blood flows into the hub. Fluids may then be given. • The palatine vein – this is present on the roof of the mouth, as its name suggests, and is paired. Cannulation may be performed with a 25 - 27 gauge butterfly catheter although the snake frequently has to be sedated or anaesthetised to gain access. • Intracardiac fluids – this can be used in emergencies. The heart may be catheterised under sedation or anaesthesia only. On turning the snake onto its back, the heart may be seen to beat against the ventral scale, approximately one quarter of its length from the snout. A 25 - 27 gauge over-the-needle catheter may be inserted between the scales in a caudo-cranial manner at 30 degrees to the body wall into the single ventricle. A bolus may be administered, or it may be taped, glued or sutured in place for 24-48 hours. • Jugular veins – these can also only be accessed via an anesthetised/sedated snake. A fullthickness skin cut-down procedure my be made 2 - 3 inches caudal to the angle of the jaw two rows of scales dorsal to the ventral scales to gain access. The jugular vein can then be seen medial to the ribs. An over the needle catheter is best for this, and should then be sutured in place, so one with plastic wings is advised. Intraosseous This route is not possible in the snake. Access Routes for Lizards Oral Gavage tubes or avian straight crop tubes or straightforward feeding tubes can be used to place fluids directly into the oesophagus/stomach. The reptile needs to be firmly restrained to keep the head and oesophagus in a straight line. The mouth is opened with a plastic or wooden tongue depressor and - 65 - British Veterinary Zoological Sociey Proceedings November 2008 the tube inserted to a depth of one third – one half the torso length of the reptile. This method is often stressful for the reptile. The alternative is to syringe fluids into the mouth, which risks inhalation in a debilitated reptile. A pharyngostomy tube may be placed for nutritional support, and so may be used for fluid therapy. Subcutaneous The lateral thoracic area is easily utilised for smaller volumes of fluids at any one site. There is a risk of the reptile involved developing a darkened pigmented area over the injection site, particularly in the chameleon, gecko and iguanid family. Intracoelomic As for small mammals, the lizard should be placed in dorsal recumbancy with its head downwards to encourage the gut contents to fall cranially and away from the injection site. The needle, preferably a 25 gauge or smaller, is advanced slowly to just pop through the abdominal wall in the lower right ventral quadrant. The plunger should be pulled back to ensure that no organ penetration had been achieved, and the fluids can be administered without any resistance. Intravenous This route can be difficult in small lizards, and frequently requires sedation or anaesthesia. A couple of routes may be tried. • Cephalic vein – this is approached in the anaesthetised lizard by performing a cut-down technique. The incision is made through the skin on the cranial aspect of the middle of the antebrachium, in a perpendicular angle to the long axis of the radius and ulna. The vessel may then be catheterised using an over the needle catheter and sutured in place. This technique is only really useful for lizards over 0.25 kg in weight. • Jugular vein – this vessel may be accessed via a cut-down technique in the anaesthetised or sedated lizard. An incision is made in a cranio-caudal manner from 1 inch caudal to the angle of the jaw. An over-the-needle catheter may then be sutured in place. • Ventral tail vein – this is more of a plexus of veins. It is accessed from the ventral aspect of the tail and can be performed in the conscious lizard. It is frequently only suitable for one-off bolus injections, and special care should be taken with species that exhibit autotomy (spontaneous tail shedding) such as day geckos and green iguanas. The needle is inserted at 90 degrees to the angle of the tail and advanced until it touches the coccygeal vertebrae. It is then withdrawn slightly with negative pressure applied to the syringe. When blood flows into the syringe, the infusion may begin. Intraosseous This is a good route for the smaller species of lizards where venous access is restricted or difficult. There are a few access points to choose from. Hypodermic/spinal needles of 23 - 25 gauge sizes may be used. • Proximal femur – this may be accessed from the fossa created between the greater trochanter and the hip joint. This route may be difficult due to the 90 degree angle the femur often forms with the pelvis. • Distal femur – this is relatively easy to access from the stifle joint. It does provide restrictions to the movement of the stifle joint, but it is easier to bandage the catheter in to this site and access to the medullary cavity of the femur is certainly easier via this route. Sedation or anaesthesia is required. - 66 - British Veterinary Zoological Sociey Proceedings November 2008 • Proximal tibia – this again is possible in the larger species. Anaesthesia or sedation are needed, and the spinal needle or hypodermic needle may be screwed into the tibial crest region in a proximo-distal manner. Access routes for Chelonia Oral This route can be used as for lizards and snakes. A pharyngostomy tube may be implanted as described below and levels of 10 ml/kg at any one time can be administered. Alternatively a stomach tube may be inserted each time it is needed. The feeding tube is first pre-measured from the tip of the extended nose to the line where the pectoral and abdominal ventral scutes connect. It can then be lubricated and passed after extending the head and gently prising the mouth open with a wooden or plastic speculum. There is marked variability in the ability to gavage chelonia. Testudo sp. can usually be gavaged conscious, whilst many Geochelone individuals need sedation to allow oral medication. Similarly, some aquatic species (e.g. Trachemys sp.) are easy to gavage, whilst others (e.g. Chelydra sp.) pose a serious threat to the handler. Post-dosing regurgitation, through mouth or nostrils is common but rarely leads to glottal aspiration. Subcutaneous This is an easily used route for post-operative fluids and mild dehydration in this species. It may be given in the area just cranial to the hind limbs, or in the skin folds just lateral to the neck. Relatively large volumes may be given via this route. Intracoloemic This route can be used in tortoises although maximum levels of 20 - 25 ml/kg/day only can be given, otherwise due to the confines of the shell, the fluids place too much pressure on the lung fields. Access sites include the area cranial to the hind limbs. This is the same site as from subcutaneous routes, but the chief difference being depth. The concern with this route is that the bladder lies in this area, and if full may be punctured. The other route is to use the cranial access site. This is located lateral to the neck and medial to the front limb. The needle is kept close and parallel to the plastron and a ¾ inch needle may be inserted to the level of the hub. Intravenous There are two main routes, the dorsal tail vein and the jugular. • Dorsal tail vein – this is more of a plexus of veins. Therefore it is often not possible to give large volumes of fluids, and certainly not possible to place a catheter. The access lies in midline, on the dorsal aspect of the tail. The needle is inserted until it hits the coccygeal vertebrae at a 90 degree angle. The needle is then pulled back whilst applying negative pressure until blood flows into the hub. • Jugular veins – these may be accessed for catheter placement in the sedated or anaesthetised tortoise. The neck is extended and the head tilted away from the operator to push the neck towards him/her. The jugular vein runs from the dorsal aspect of the eardrum along the more dorsal aspect of the neck. An over the needle catheter may be directly placed, or in thicker skinned animals, a cut down technique employed. Intraosseous Two main sites can be used: • Plastro-carapacial junction/pillar – this is the pillar of shell which connects the plastron to the carapace. It is approached from the caudal aspect, just cranial to one of the hind-limbs. The spinal/hypodermic needle (21 - 23 gauge) is screwed into the shell attempting to keep the angle of insertion parallel with the outer wall of the shell, so entering the shell bone marrow cavity. In larger older species, the shell may be too tough to allow penetration in this method. - 67 - British Veterinary Zoological Sociey Proceedings November 2008 • Proximal tibia – this may be approached as for lizards. The area is thoroughly scrubbed and the hypodermic/spinal needle is screwed into the tibial crest in the direction of the long axis of the tibia distally. Supportive Nutrition Carnivores All snakes (some are mammal-consuming in the wild e.g. cornsnakes, and most boas and pythons; some are fish-consuming in the wild e.g. water snakes/ garter snakes; a few are specialized e.g. egg-eating snakes, or the kingsnakes that eat other snakes - all can be converted on to rodent prey in captivity) Herbivores Green and rhinoceros iguanas Omnivores Bearded dragons Box turtles Mediterranean (Testudo Red eared terrapin spp) tortoises Geochelone tortoises e.g. leopard, African spurred, starred etc. Water dragons Skinks Geckos (mainly insectivorous) Snapping turtles Spiny tailed lizards (agamas) Terrapins Marine turtles Collared lizards Anoles Savannah monitor Chameleons (insectivores) Table 3: Commonly seen species of reptiles and their trophic groups For initial emergency nutrition, as with birds, the use of products such as Vetark’s Critical Care Formula are useful to give simple sugars and amino acids. For further nutrition, the carnivorous species may be administered products such as Hills a/d or Virbac’s Reanimyl and the herbivores/omnivores may be administered vegetable based baby foods such as Milupa or Cow and Gate (avoid lactose containing products). Calculation of energy requirements can be made using the formula BMR = k x (weight (kg) )0.75 Where k the constant is 10 for all reptiles. Remember that MER (metabolic energy requirement) is generally 1 ½ - 2 x the BMR (basal metabolic requirement) and if disease is present then this further amplifies the required calories (sepsis and burns for example may increase MER by 2 – 3 x). Other Useful Drugs and Techniques It should be noted that most sick reptiles are borderline or fully septicaemic. They tend to be attacked by their own gut bacteria which are generally Gram-negative in nature, and often contain the Salmonella and Pseudomonad bacterial family. Therefore a bacteriocidal antibiotic with good action against Gram-negative bacteria should be used. These include the fluoroquinolones and third generation cephalosporins. It should be noted that in order to follow the veterinary prescribing - 68 - British Veterinary Zoological Sociey Proceedings November 2008 cascade, the drug enrofloxacin as ‘Baytril 2.5 % ®’ (Bayer Plc) is the only licensed antibiotic for reptiles in the UK. Many nutritional/husbandry diseases are common in reptiles including metabolic bone disease and hypocalcaemic tetany in egg -ound mature lizards such as the Green iguana. Calcium gluconate at 100 mg/kg may be administered in an emergency. Some of these lizards may fit, and diazepam, or midazolam, may be administered (see table 7). Garter and water snakes fed salt water fish that has been previously frozen may suffer from a relative deificiency of vitamin B1 (thiamine) which can lead to a neurological condition (similar to cerebro-cortical necrosis in grain-gorged cattle) manifesting as an inability to right itself and continual star gazing. Injections of vitamin B1 at 25 - 35 mg/kg may be effective if administered quickly. Cardiovascular and respiratory disease are relatively common and pneumonia or lung oedema may result. Use of diuretics such as furosemide and hydrochlorothiazide may be helpful. Oxygen therapy can be used, but care should be taken as the impetus for breathing in reptiles is a lowered pO2 rather than an elevated pCO2 as occurs in mammals, therefore providing 100 % oxygen for even short periods of time can stop breathing altogether. As reptiles do not have a cough reflex (no diaphragm) and are relatively easy to intubate, conscious intubation of collapsed reptiles can be performed and IPPV administered for a short period. If cardiac arrest occurs, intubation and intra-tracheal administration of adrenaline should be attempted. Reptiles can cope with a degree of hypoxia beyond that tolerated by mammals. IPPV after intubation is essential, although chest massage in the case of lizards and moving limbs into and out of the shell in chelonian may also be successful, aiding the pumping of air into and out of the lungs. Drug Adrenaline Dosage 0.05-0.5ml depending on size of reptile Allopurinol 10-50 mg/kg PO SID Calcium gluconate 100 mg/kg IM/SC/intracoelomically Ceftazidime (Fortum® Pfizer) 20 mg/kg SC/IM/IV q72hrs Diazepam Doxapram Enrofloxacin 0.2-0.5 mg/kg IM/IV 0.5 mg/kg PO/IV 5-10 mg/kg SID Furosemide 1-5 mg/kg Hydrochlorothiazide Midazolam 1 mg/kg 0.2-0.5 mg/kg IM/IV Meloxicam 0.2-0.3 mg/kg IM/PO SID - 69 - Notes Use intratracheally after intubation and IPPV with 100% oxygen Reduces uric acid production to aid management of gout. Hypocalcaemic tetany especially in female eggbound green iguanas Broad spectrum bacteriocidal third generation cephalosporin; particularly effective against Gram negative bacteria Muscle necrosis if given IM Intubate and use IPPV Licensed antibiotic for reptiles. Useful against Gram negative bacteria but not against anaerobes. Can cause muscle necrosis. Diuretic but action not known Diuretic Less likely to cause muscle necrosis than diazepam Beware use if already has renal damage British Veterinary Zoological Sociey Proceedings November 2008 Oxytocin Chelonians 10 IU/kg IM Lizards 5-20 IU/kg IM Snakes 20-40 IU/kg IM Silver sulfadiazine cream (Flamazine® Smith&Nephew) Vitamin B1 Topical on burns/wounds 25-35 mg/kg IM/PO/SC Uterine muscle stimulant. May be repeated on max of 4 occasions. Useful to administer calcium gluconate first Effective cream against Gram negative bacteria and some fungi Thiamine deficiency (fish eating snakes) Table 4: Commonly used emergency and recovery medications for reptiles Suitable intramuscular injection sites Snakes Epaxial musculature midway between dorsal midline and lateral aspect of body. Preferred site is 33 % of snout-vent length. Lizards Triceps brachii (caudal aspect of humerus) Caudal antebrachium (large individuals) Quadriceps femoris (cranial femoral region) Epaxial musculature in lumbar area Epaxial musculature of tail (but be aware that this may initiate tail-dropping in some (especially gecko, lacertid and small iguanid species) Chelonia Triceps brachii (caudal humeral area) Quadriceps femoris (cranial femoral area) Any palpable muscle mass if animal refuses to be withdrawn from shell. In addition, medications may be administered via intravenous, intraosseous and intracoelomic routes where appropriate as described for fluid therapy access above. Nebulisation Achieving therapeutic levels of any antibiotic in infected reptile lungs is difficult. The bloodair barrier is thicker in reptiles than in mammals, plus reptiles have a poorly developed or absent cough reflex. Add to this the fact that caseous, impenetrable purulent discharges are common and many of the most effective antibiotics such as the aminoglycosides are potentially toxic if given in effective doses systemically, it can be seen that a topical respiratory method, such as nebulisation of a drug is attractive. Although the possibility exists that a significant proportion of the drug could be absorbed across an inflamed respiratory epithelium signs of e.g. aminoglycoside related nephrotoxicity are not seen following aerosolised administration of these drugs. Other drugs suitable for nebulisation include antiseptic-disinfectants (F10®; Health & Hygiene Ltd.), soluble steroids in inflammatory conditions, bronchodilators and agents aimed at reducing the viscosity of respiratory secretions. - 70 - British Veterinary Zoological Sociey Proceedings November 2008 Medication Concentration Notes Amikacin 50mg in 10ml saline Gram negative infections Amphotericin B 100mg in 15ml saline Aspergillosis Enrofloxacin 100mg in 10ml saline Gram negative infections F10® (Health and Hygiene Pty) 4ml in 1 litre deionised water Aspergillosis and bacterial infections Gentamicin 50mg in 10ml saline Gram negative infections Piperacillin 100mg in 10ml saline Gram negative and some Gram positive infections Table 5: Drugs which may be nebulised for administration to reptiles - 71 -