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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
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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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.
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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
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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
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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.
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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
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