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My 2016 RUSVM Anesthesia > Special Species Dr. Bennett > Flashcards

Special Species Dr. Bennett Flashcards

1
Q

What are considered special species?

Considerations

A

Small mammals

incr pub awareness they are capable of experiencing pain & distress

specific challenges due to:

unfamiliar species

unfamiliar drugs

research requirements & legislation

ethical aspects of research projects

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2
Q

What may be some causes for anesthetic deaths in rabbits compared to dogs & cats

A

maybe relate to CV & resp problems

? due to large surface area:volume ration

high metabolic rate & high rish of hypoglycemia

difficult to intubate due to small size & problems of maintaining patent airway

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3
Q

Pre anesthetic assesment of small mammals

A

rats, mice & hamsters are nocturnal

rabbita are activea at dawn & dust (crepuscular)

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4
Q

pre anesthetic management of small mammals

A

No fasting due to:

Rats & mice do not vomit, prone to hypoglycemia & dehydration

Rabbits & GP experience GI disturbances leading to changes in gut flora, ileus & enterotoxemia

All spp exhibit neophobia (fear of new things) - feed usual diet

plus high-energy & high water content

all are coprophagic- avoi use of E collar

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5
Q

Complications seen in anesthesia of sm mammals

A

high risk of hypothermia

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6
Q

How to administer drugs to small mammals

A

SQ preferred into scruff or flank

IP may be unreliable

IM (avoid if volume large)

use drugs w/ wide safety margin

ideally are reversible

e.g. Alfaxalone

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7
Q

IV access in sm mammal spp

A

Rats: lateral tail v., make sure they are warm

Rabbits: auricular, cephalic & saphenous v.

GP & ferrets: cephalic v. (potentially saphenous v. also)

Use EMLA cream prior

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8
Q

What is most commonly used injectable in lab rodents

A

Ketamine

used in combo with Alpha2 agonist

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9
Q

Inhalant anesthetics in sm mammals

A

Isoflurane & sevoflurane

adverse effects well documented

can be used in all common lab rodents

isoflurane undergoes virtually no biotransformation

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10
Q

Considerations of inhalant anes drugs w/ sm mammals

A

Mask induction may be associated w/ breath holding esp in Rabbits

some aversion to inhalants due to smell in rats & mice

less with Sevo & halothane than Iso

Iso particularly irritating to GP

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11
Q

Airway management & intubation of sm mammals

A

placing ET tube narrows the airway & increases resistance to exhalation & potentiall the work of breathing

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12
Q

Rabbit intubation

A

specific laryngoscope available for rabbits

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13
Q

Types of breathing systems used in sm mammals

A

T-piece & Bain:

non-rebreathing

low resistance

need ot minimize dead space in order to prevent rebreathing

TV: 5-10 mL/kg small rodents

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14
Q

Maintenance of body temp in sm mammals

A

electric & warm water blankets available

forced hot air blankets not practical in rats & mice

recover in an incubator

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15
Q

Postoperative care & pain assessment in sm mammals

A

Can have changes in facial expression!

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16
Q

Opioids in small mammals

A

Buprenophine used most commonly

35 x as potent as morphine in rats IM

long duration of action: 3-5 h mice, 6-8 h rats

less incidence of respiratory depression

May cause pica esp in rats

analogous to vomiting in other spp

if occurs switch to non opioid analgesic

17
Q

NSAIDs in sm. mammals

A

all drugs licensed fro use in animals can be administered in lab animals

oral meloxicam is highly palatable

duration of action not clear

8-24 hours

18
Q

Local anes in sm mammals

A

may be suitable for some procedures in combo with GA

dont exceed:

Lidocaine 10 mg/kg

bupivicaine 2 mg/kg

19
Q

Gabapentin & pregabalin in sm mammals

A

MAC sparing effects of gabapentin in rats using both iso & sevo

20
Q

Specifice Ferret anesthesia

A

sedation: medetomidine & butorphanol, reversal with atipamezole

21
Q

What are most commonly encountered reptiles for anesthesia

A

Crocodilians (alligators & crocs)

Chelonians (tortoises & turtles)

Squamates (snakes & lizards)

22
Q

Species specific considerations for reptiles

A

Metabolism & thermoregulation

CV system

Pulmonary system

Renal system

Hepatic system

some spp terrestrial & others aquatic!

23
Q

Reptile metabolism & thermoregulation

A

Poikilothermic/ectothermic

lower rates of metabolism compared to mammals

oxygen consumption varies from almost zero to that of a restin mammal (spp dependent)

Perferred optimal temperature zone (POTZ)

ensures optimal metabolic function

approx 20-25° C for aquatic & temperate spp

25-35° C for tropical spp

24
Q

reptile CV physiology

A

Squamates & chelonians

3 chambered heart - 2 atria 1 ventricle

Crocodilians

4 chambered heart somewhat similar to mammals

blood can be shunted from R-L & L-R

can lead to awakening during anesthesia

may affect patient monitorin e.g. blood gas analysis & SpO2

BP varies by spp & environment

values vary between 15-30 mmHg in chelonians, 60-80 mmHg in lizards

25
Q

reptile pulmonary system

A

Chelonians & lizards:

paired lungs

chelonians obligate nasal breathers

Snakes

single functional R lung

many also possess a R tracheal lung

functional units are ediculi & faveoli analogus to alveoli

anesthetic drugs may have more respiratory depressant effects compared w/ mammals (lack of diaphragm)

Chelonians: dorsal survace of lung is attached to carapace, ventra surface to abdominal viscera, no ribcage, mm used in locomotion are also involved in ventilation

high FiO2 may depress ventilation

recovery may be faster breathing room air (green iguana)

26
Q

renal system of reptiles

A

blood from hind limbs & tail may pass via the kidney before returning to heart

little apparent effect on drug PK in healthy animals

preferable to avoid nephrotoxic drugs inj into hindlimbs

27
Q

hepatic system of reptiles

A

similar in structure & function to mammals

metabolic capacity lower than mammals

thought to be responsible for prolonged recoveries seen after anesthesia

28
Q

Pt assessment of reptiles

A

obtain bodyweight & assess gen. appearance

Maintain POTZ

29
Q

Drug admin in reptiles

A

Snakes: IM epaxial muscles

lizards: IM triceps, biceps, quadriceps, semi-mem & semi-tend & tail

Don’t use tail in gecko!

Snakes and lizards
ventral coccygeal vein
palatine vein
Tortoise and turtles
dorsal coccygeal vein
IV catheterization
coccygeal and abdominal veins
jugular vein in tortoises

Venous sinuses
using stylet of an IV catheter

30
Q

Sedatives used in reptiles

A

Benzodiazepines and alpha2-adrenoceptor agonists in combination injectable anesthetic drugs usually IM.
E.g. Medetomidine
◦E.g. Midazolam
both can be reversed

31
Q

injectable anesthetics

A

Propofol
drug of choice if IV access is available
give slowly to avoid respiratory depression
CRIs have been used in Green iguanas

Alfaxalone

minimal effect on HR & ventilation

Ketamine

effects (spp/dose) dependent

recovery may be prolonged

32
Q

intubation in reptile

A

In chelonians and crocodilians
tracheal rings are complete –avoid cuffed ET tubes
In chelonians
trachea bifurcates quite rostrallyso it is easy to intubate a bronchus

33
Q

Maintenance of anesthesia in reptiles

A

Iso or sevo

Options
IM sedation –large and aggressive animals

ketamine +/-medetomidine or midazolam
tiletamine+zolazepam
IV induction of anesthesia
propofol
alfaxalone
Mask or chamber induction

34
Q

Fluid therapy of reptiles

A

some debate since blood is hypotonic compared to birds and mammals
use isotonic saline diluted (9:1 with sterile water)
“reptile ringers” -> 2 parts 2.5% dextrose/0.45% saline and 1 part LRS

may use lactated of acetated fluids
some query about ability to metabolize lactate

hypertonic crystalloids and colloids may be used in hypovolaemic animals
start at 1-2 mL/kg and re-assess

35
Q

anes monitoring in reptiles

A

ECG
differences from mammals in configuration
ETCO2
not reliable due to intra-pulmonary shunting of blood
pulse oximetry
not validated for reptilian species
◦protect the eyes

36
Q

pain assessment & mgmt in reptiles

A

Opioids
species differences in response

some information about morphine, tramadol, buprenorphine, butorphanol and hydromorphone
NSAIDs
evidence supports the efficacy of these drugs
Meloxicam
high bioavailability PO
dose 0.2 mg/kg IV or PO
Local anesthetics
lidocaine

My 2016 RUSVM Anesthesia (22 decks)

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