Exotic Anaesthesia Flashcards
how do anaesthetic mortality rates in exotics compare to those in companion animals?
much higher risk in exotics
what is the issue with history in exotics?
often sparse
may have may pre existing conditions which have gone unrecognised
as they are often children’s pets (e.g. hamster) there may be financial constraints
what are the key issues associated with anaesthetising exotic species?
often small may have completely different anatomy to companion animals can be dangerous handling is stressful for the animal lack of 'standard' equipment
what are the difficulties associated with the often small size of exotic species?
accurate weight may be difficult
difficult to examine / auscultate
IV access may be impossible
what are the key issues associated with the eyes of many exotic species?
often protuberant
risk of damage to occular surface by mask
e.g. corneal desiccation
in what animals is the pharyngeal pouch found?
guinea pigs
what issues are associated with pharyngeal pouches?
if pouches have food in this can be pushed into the trachea during intubation
what are the difficulties associated with the mouth anatomy of many exotic species?
dentition (e.g. large incisors)
narrow jaw
limited gape
extra pharyngeal tissue which may be obstructive
what does the mouth anatomy of many exotic species mean for intubation?
often difficult
what is the metabolic rate of many exotic species like?
high
what is the oxygen consumption of many exotic species like?
high
what is the rate of glucose consumption in many exotic species like?
high
what blood disturbance are many exotic species at risk of due to there high consumption of glucose?
hypoglycaemia
why are many exotic species at risk of hypothermia?
high surface area:volume ratio
high rate of heat loss
many ectothermic
what are the key difficulties with the respiratory system of exotic species?
may be an obligate nasal breather
many have pre-existing, undetected disease
difficult to detect changes with auscultation
what species is an obligate nasal breather?
rabbit
what are the key difficulties with the cardiovascular system of exotic species?
small vessel size
high HR makes for difficult monitoring
what are the key difficulties with the GI tract of exotic species?
may be carnivores or herbivores and have differing dietary needs
what is an issue with rabbit GI tracts?
at risk of gut stasis / ilius if they aren’t eating
what are the main concerns between exotic species when under veterinary care?
disease / problem species predisposition drug concerns (licensing in species) poor husbandry due to lack of knowledge lack of familiarity lack of specialist housing
what is a species specific problem found in ferrets?
hyperoestrogenism
what is a species specific issue in rabbits?
liver torsion
what are the key special considerations with handling / anaesthetising birds?
wide range of species hide illness well stressed by restraint danger to handler risk of hypothermia and hypoglycaemia must be weighed accurately
how does a bird breathing system differ from mammals?
separate conducting and gas exchange areas
have air sacs, parabronchi and unidirectional flow
movement of sternum is essential for breathing
why must birds be handled very carefully?
require chest to move in order to breathe as they don’t have a diaphragm
why should ET tubes in birds not be cuffed?
they have complete tracheal rings
in what size birds is tracheal intubation possible?
> 100g
why do muscle relaxants have a profound effect on birds?
both inspiration and expiration are active processes
where is IV access best found in birds?
right jugular usually better than left
can also use wing veins and dorsal metatarsal vein
how does birds heart rate compare to mammals?
have a large heart and CO so HR is lower
what is the metabolic rate of birds like?
high
should birds be starved pre-op?
not unless over 200g and dependent on size and species
how can birds be encouraged to eat post op?
crop feeding
what are the key husbandry considerations of reptiles?
humidity (POTZ)
UV
Light
maybe involve owner
what is a big handler risk with reptiles?
zoonosis (on skin)
how do reptiles regulate body temperature?
poikilothermic or ectothermic
define poikilothermic / ectothermic
temperature can fluctuate in a wide range
temperature control is mostly due to the environment
what is the effect on anaesthesia of correctly managing ectothermic animals temperature?
maximise drug absorption. metabolism and elimination
minimise potential for lactic acidosis
reduce recovery time
why is muscle function of anaesthetised reptiles crucial?
no muscular diaphragm
is the heart within reptiles in a fixed location?
no heart and organs can move freely
are reptiles able to breath hold?
yes
when are reptiles larynx open?
only during active respiration?
describe the reptillian heart
3 chambers - 2 atria and 1 ventricle
what is the result of blood shunting the wrong way in the reptillian heart?
gas mismatching / poor inhalation uptake
what makes intubation of reptiles challenging?
fleshy tongue and long soft palette
how may reptiles loose moisture?
via respiratory tract
how does reptilian O2 consumption compare to companion animals?
lower
what is the arrangement of lungs like in many snakes?
single functional right lung and not a pair
why should cuffed ET tubes be avoided in reptiles?
many species have complete tracheal rings
what is key to remember about snakes eyes?
they don’t have eyelids
how is gas movement in and out of the respiratory system produced in chelonians?
movement of the limbs
do tortoises have a diaphragm?
no
what will thermoregulation in chelonia affect?
drug uptake, absorption and distribution
what is the MAP of chelonians?
15-30 mmHg
how can chelonian respiration be observed?
watching movement of limbs
should rabbits/rodents be starved pre-op?
no
should guinea pigs be starved pre-op?
0-4hrs prior to ensure pharyngeal pouches are empty
should ferrets be starved pre-op?
yes, 6 hours
should snakes/reptiles be starved pre-op?
regurgitation is not usually a problem
avoid feeding live insects prior to GA - potentially avoid feeding day as not fed as often as companion species
should birds be starved pre-op?
varies between species
should tortoises be starved pre-op?
avoid live insects before GA
what condition do exotic species often present with?
anorexia
what breathing system will be used for most exotics?
T-piece
how can drag on the trachea by the breathing system be reduced?
weight of breathing system taken by sandbags
what is often the only method of induction available for exotics?
gas induction - must be justified
what is crucial about container sizes for gas induction?
appropriate for size of animal to ensure quick induction
what must gas chambers have?
inlet and outlet for scavenging
where will the out port on a gas chamber be placed in relation to the in port?
higher as warm waste gases will rise
why may gas induction not be applicable to some species?
they can breath hold
what is the most common airway management method in exotic species?
mask
what are the advantages of masks for airway management?
suitable for all species
clear mask allows observation
easy to use
can provide O2 and VA
what are the disadvantages of masks for airway management?
personnel safety
no airway protection if animal vomits
what are the advantages of ET tubes for airway management?
gold standard
accurate gas delivery
better for personnel
what are the disadvantages of ET tubes for airway management?
not possible in all species
may cause trauma
care with one lung ventilation - ensure correct placement
what are the advantages of V-gels (SGA) for airway management?
great for rabbits
quick and easy to use
online training available
cost effective
what are the diadvantages of V-Gels (SGA) for airway management?
not a substitute for intubation
requires multiple sizes
weight dependent
not always easy to keep in place (especially if animal is being moved regularly)
must have capnography to confirm placement
why can intubation in birds sometimes be easier?
no epiglottis
why is pain relief essential in rabbits?
must eat - if in pain will stop eating
how can rabbits be fed ASAP post operatively?
syringe feeding - avoids gut stasis
what are the main routes of drug administration in exotic species?
IV IM IP SC IO inhalation oral
what veins may be used for IV injection in exotics?
usual - cephalic and saphenous
basilic vein (wing
medial tarsal
right jugular
what muscles may be used for IM injection in exotic species?
usual sites
pectoral in birds
what bones may IO injections be placed in in exotic species?
cranial tibiotarsus
ulna
what are exotic species susceptible to following drug admin?
abscessation and septicaemia
what can be done to reduce abscessation and septicaemia following drug admin in exotic species?
aseptic preparation
what should be done following SC or IM injection?
massage site
what is monitoring of exotic anaesthetic reliant on?
reflexes
what reflexes can be monitored in exotic species?
the Righting reflex
withdrawal reflexes
jaw tone
what is the Righting reflex?
vestibular system will correct orientation of body if it is incorrect (head will follow body - test by placing animal on its back and seeing if it turns over)
what pulses should be monitored in exotic species?
peripheral if possible - central if not
what is essential about any monitoring device used for exotic species?
can count up to and over 200BPM
where can pulse ox be attached on exotic species?
foot or tail base as tongue may be too small
what capnography is best for exotic species?
mainstream - to stop delay in CO2 readings that is associated with sidestream sampling
How can ECG leads be attached?
cut pads to size and attach to feet / limbs
needle electrodes
where should ECG pads be placed on ferrets/rats?
pad of foot
where should pads be placed on rabbits?
metacarpal / tarsal
what are needle electrodes?
SC hypodermic needle attached to crocodile clip
what type of BP monitoring is most common in exotics?
doppler (indirect)
what can doppler BP also be used for?
apex beat / CO monitoring
in what species can doppler BP monitoring be used?
wide variety - particularly good in rabbits
what can be useful about doppler monitoring in species with no BP values?
can be used to track trends
when is direct BP monitoring often used in exotics?
lab settings
what arteries are often used for direct BP in exotics?
carotid
femoral
tail
what should exotic temperature be monitored with?
rectal probe (mind size used!) as mask will make oral difficult
what can the doppler probe be used for as well as BP monitoring?
placed over heart to give audible heart rate
where should a doppler be placed on a snake when using it as a stethoscope?
place on apex beat
where should a doppler be placed on a snake when using it as a stethoscope?
apex beat
what is apex beat?
most inferolateral point on the chest where the cardiac pulsation can be palpated
where should a doppler be placed on chelonians when using it as a stethoscope?
at the thoracic inlet or on the plastron at the junctio between the pectoral and abdominal scutes (in smaller species)
where should a doppler be placed on a lizard when using it as a stethoscope?
at thoracic inlet, over the thoracic girdle or aimed close from behind
how long should monitoring of exotic anaesthesia take place?
should be continuous until the animal is moving around
what should be done during recovery from anaesthesia in exotics?
temperature regulated and monitored
in a safe environment
pain managed - particularly in prey species
encourage to eat (maybe not in reptiles)
what is crucial about pain management in exotic species?
learn about pain signs in the specific species you are treating
what are signs of acute pain in exotic species?
withdrawal of painful limb escape behaviours avoidance aggression restlessness increased resp rate
what are signs of chronic pain in exotics?
immobility
‘stinting’
aggression
- not as easy to identify as acute
