Workshop- Anaesthesia of Small Mammals and Exotics

how long do you starve rabbits before GA?

you don't want to starve them as they can't vomit, make sure they have eaten a few hours before

just remove food and rinse mouth abt 30 mins before intubating

Why may you remove food from the enclosure before inducing ?

removing food 30 minutes ish before induction means there will be less food in their mouth when you intubate

why is reducing stress so important in rabbits pre-anaesthesia ?

stress releases catecholamines and this can cause arrythmias, and resistance to drugs - higher doses needed have more side effects.

they are prey animals

can cause gut stasis too

how do you ventilate rabbits, devices, form and considerations?

- ET tubes (more difficult as they have an elongated soft palate),

- masks - for shorter procedures (they are obligate nose breathers)

- supraglottic device (v-gel - easier to place, but can move if animal moves), IPPV (manual ventilation)

use a non-rebreathing system (mini lack or T-piece) because of their size and ratio of lung to body.

attach to capnograph

why do you have to be careful if moving patients when theyre ventilated

• Tracheal tube wont move

• Vgel only on top of glottis so could move if animal moves and system doesn’t-> not ventilated anymore

Can you intubate ferrets and other small furries ?

complicated due to size and anatomy of the trachea

can use an endoscope to visualise

intubation is not usually done

how do you position rabbits and why is this different from dogs and cats?

elevated thorax and head because guts puts pressure on the diaphragm, and straighten neck for optimal ventilation

• don’t want neck falling down onto chest when doing this as tube could be bent so try make head and neck straight

what equipment do you use to monitor you rabbit under GA?

- capnograph (esp for v-gel),

- pulse oximetry on auricular vein (difficult, made for dogs, and rabbits very furry),

- blood pressure monitor - not very accurate.

• Doppler hard to catch pulse

• Oscillometric machine nice but only usually works when bp is normal -> low pressure wont give number

  • So if give reading its ok, but if not then is probs low

• Invasive in a -> usually lot of bleeding and clotting/ necrosis of eat, can be expensive too -> only really if you really want to know

- temperature - anal probe more effective

• Oes temp probe not best bc tend to bite

- doppler - rate and rhythm, other equipment may not be reliable for small furries

- ECG - pads don't work, clips do but be carful on small ones

how will you prevent hypothermia in your rabbit?

- heated pads (not weight triggered)

- bair huggers (can be too big)

- fluid warmer

- small amount of clipping

- cover ears - sock or bubblewrap

how can you increase a rabbits blood pressure

IVFT - bolus,

reduce isoflurane,

give drugs to counteract

• glycopyrrolate -

• instead of atropine bc have the enzyme

wake animal up if possible, adrenaline for crash

what drugs would you administer to your rabbit during GA to ensure a quick recovery

pain relief,

reverse any drugs,

keep them warm,

gut stimulants if needed

how long do you starve your bird before GA

you want their crop to be empty

• Crop doesn’t have sphincter on proximal end to is open -> content will come out

budgies around 1 hour, parrots, chickens around 3 hours

variablility in size, water foul ?

raptors - dont typically need starve as they don't eat frequently, but if procedure in morning don't feed in morning.

palpate crop

• Palp crop if empty is okay -> wait if not

• But in crop stasis it will be full and cant do owt

Need to find balance between emptying of crop and glucose of gut (don’t want hypoglycaemic)

• hypoglycaemia is more common is passerines

how will you ventilate your bird

ET tubes,

• Can use iv catheter -> may get secretions stuck in them tho

masks.

DO NOT use cuffed tubes.

• Closed rigns in trachea so esp important no cuff -> necrosis of mucosa of tracha if cuff-> stenosis

caudal air sac ventilation (O2 and iso) cannot use if cutting into coelomic cavity, but bypasses neck and secretions

Why is it important that you ventilate a bird (manually or mechanically)

CO2 release makes birds stop breathing

lack of diaphragm makes them stop breathing

dorsal recumbancy - organs compress airsacs

if they burst CO2 is released

How do you intubate a parrot ?

trachea gets narrow in the distal section - so don't use tube size that fits glottis. stop when there is any friction (complete rings)

or use a specific parrot tube

why might a fracture of the birds humerus effect the respiratory tract

pneumatised bones - air leaves bones. different birds have different pneumatic bones, but humerus is in most

What are some considerations for open fractures in birds?

infection coming in

air going out of pneumatic bones- reduced respiration capacity

blood in resp system

how will you clean ? - fluid will go into airsacs

•  so don’t OR flush with small amounts at a time and use aspiration devise at the same time so doesn’t go to resp system

considerations for closed fractures in birds

• Less of an issue bc no exposure to external environment

• but in Surgery -> once cut skin -> is now open fracture so same as before

what equipment do you use to monitor your bird under GA?

capnography, stethoscope, blood pressure, doppler, thermometer

SPO2 - reading will not be reliable, but can give you pulse waves

• Thin skin so works quite well

ECG - be careful with clips - use less trauma

temp- cloaca, oesophagus (not parrots bc their beak will break probe)

doppler

• On wing (ulnar a on inside of wing)

  • Clamp it on with the tongue depressors

• Listen to rhythm of pulse

how will you prevent hypothermia in birds?

bair huggers, no surgical spirit, heat pads, hot hands, minimal plucking, keep them as dry as possible

• Feathers acta as an isolating device if you keep them dry -> easier to maintain temp

• Wet makes the transfer of temp easier -> colder quickly

how could you administer fluids to this bird whilst under GA?

IV - into the wing ulnar vein or jugular vein,

SC - inguinal flap,

IO

• easier to place but remember pneumatic (tibiotarsal bone (bigger and easier, goes through knee), ulnar bone (distal to proxmial, harder but eaier when woke up))

how do you ventilate a tortoise?

ET tube - never cuffed, IPPV or electric ventilator is needed to keep them breathings - tortoises use their legs to induce breathing, when unconscious, they can't do this. once or twice a minute.

never gas them down - they will hold their breath and have low resp rate so too long

How quickly will reptiles take to start breathing post anaesthesia

slow recovery they will take a long time

why is it important to keep tortoises temperature as close to 30 degrees as possible?

They need external sources of heat to regulate their temperature, their metabolism is low so we have to keep it steady. Drugs will take longer to take effect if they are cold

• Low temp -> low metabolic rate -> dcrs hr -> drugs take longer to move round the body -> longer to take effect

and they will take a long time to warm up if they're cold

what equipment do we use to monitor a tortoise (reptiles) under GA?

doppler

• Peripheral bp of reptiles is normally low

• on heart is best

• Tortoise on shell where heart would be if small enough

  • If big on between neck and shoulder

BP - not reliable measure in reptiles - it is low even on invasive read.

capnograph (levels not reliable),

oesophageal or cloacal stethoscope

pulse oximeter (not accurate because of scales, and tongues not long enough to exteriorise.

ECG - chelonians have 3 ventricles so wave is different but is accurate to HR, use needles and clamp clip to needle (scales)

• Stick needles into skin then clip to needles

How will you use a temperature probe in reptiles

mouth or cloaca

How do you use a doppler for a reptile or chelonian?

peripheral blood pressure is very low - will need to be placed directly on top of their heart - know the anatomy. You may find a pulse close to the entrance of the neck/ shoulder

what stimulates a reptile to breath?

their oxygen levels, when they are low they are stimulated to take a breath. higher blood pH and can do a lot of anaerobic resp, so high CO2 doesn't effect them

why can reptiles sometimes not breath when waking up?

the oxygenation you provided is still lasting and they won't be stimulated to breathe. ventilate with an ambo bag - to deliver lower oxygen

So on recovery stop the oxygen disconect tube and ventilate with abu bag or room air (use o2 in air) -> help stimulate the breathing

why might you not be able to keep the tube connected to reptiles when theyre waking up

They will wake up/ move before they start breathing

• So may not be able to keep the tube connected -> take tube out (and move legs in tortoise)