Exam 1 - Euthanasia: Lecture & Critical Thinking Flashcards
what are the 5 most important aspects of evaluating euthanasia methods?
- ability to induce loss of consciousness & death with minimum pain & distress
- time required to induce loss of consciousness
- documented emotional effect on observers or operators
- safety for predators or scavengers should the remains be consumed
- environmental impacts of the method or disposition of the animals remains
what is the definition of an ‘acceptable’ method of euthanasia?
those that consistently produce a humane death when used as the sole [primary] means of euthanasia
what is another term used for ‘acceptable’ method of euthanasia?
fully acceptable
what is the definition of ‘acceptable with conditions’ method of euthanasia?
equivalent to acceptable methods when all criteria for application of a method can be met
what is another term used for an ‘acceptable with conditions’ method of euthanasia?
conditionally acceptable
what is the definition of an ‘unacceptable’ method of euthanasia?
those methods deemed inhumane under any conditions or that the [AVMA panel] found posed a substantial risk to the human applying the technique
what are the 2 general categories for primary methods of euthanasia?
pharmacologic agents (overdose**) - inhaled is conditionally acceptable & injectable is fully acceptable
physical - conditionally acceptable
why is an inhaled pharmacologic agent used as a primary method of euthanasia conditionally acceptable?
you must get the animal to a point where it is irreversible - make sure heart & respirations have stopped
what are the 2 main requirements for using physical methods of euthanasia?
- operator must be proficient
- equipment must be kept in good condition
what is an example for keeping equipment in good condition regarding using a guillotine as a physical method of euthanasia?
sharpening services - vinyl tubing to confirm sharpness, only a few companies
T/F: guillotines are largely used in research facilities
true
T/F: ‘after-effects’ of euthanasia are more commonly seen with physical methods of euthanasia, so you should prepare yourself, staff, & clients for what that may look like
true
what are the major signs associated with ‘after-effects’ of physical methods of euthanasia?
- leg kicking!!!!!! large muscle groups involved, & can be vigorous
- muscle twitching
- skin twitching
- death ‘sigh’ or ‘hiccup’ - diaphragm
why do ‘after-effects’ occur in euthanasia?
effect of spinal stimulation & residual ATP storage in the muscle
leg kicking is not uncommonly seen with what physical method of euthanasia?
captive bolt
what is the point of using a secondary method of euthanasia?
when you’re not sure if irreversibility is achieved
when should the secondary method of euthanasia be used?
only used after you are absolutely sure the patient is unconscious
what are 3 reasons you should use a secondary method?
- ensures the animal can’t return to consciousness
- in case primary only stuns/knocks them out or goes wrong (dislocation of T13-L1 instead of C1-C2)
- pharmacologic - can be a fine line between dose & overdose, need at least 3x the upper anesthetic range, especially common in drugs not labelled for euthanasia
what is the most common secondary method of euthanasia used that works well for all species? why is it ideal?
penetration into the thorax - removes thoracic negative pressure, so it ensures that the heart & lungs stop
how is penetration of the diaphragm used as a secondary method of euthanasia?
if the abdomen is open (post surgical euthanasia)
in necropsy, you can assess lungs, & you want to see them shrink back into the chest showing that negative pressure was there
what species will thoracic penetration not be useful for a secondary method of euthanasia?
amphibians - some are lung-less
other than thoracic penetration, what are 2 other secondary methods?
- cervical dislocation
- exsanguination - animal must be unconscious first for transection of major vessels (axial a./v. easiest to perform in some rodents/avians)
when disposing of euthanized animals, what must be considered?
environmental effects!
barbiturates in carcasses - access to wildlife
rendering (non-edible) limits
what is the procedure of using injectable anesthetic overdose for small rodents?
pentobarb, beuth-d
largely by IP route - lower right quadrant is preferred, enter at a shallow angle, target is the last row of nipples
why is the lower right quadrant the preferred target for injectable anesthetic overdose for small rodents?
avoid urinary bladder, cecum, gi - animal can void it out
what is the fastest method not requiring a lot of technique for euthanasia of small rodents?
gas anesthetic overdose using isoflurane, sevoflurane, or desflurane
what is the disadvantage of using gas anesthetic overdose for small rodent euthanasia?
there is an aversive smell - distress in the first minute
if you use gas anesthetic overdose for euthanasia of small rodents, how can a mask be used? what about an induction chamber?
mask - only have to cover the nose because there are obligate nasal breathers
induction chamber - must block the scavenge outlet
how can you reduce occupational hazards associated with gas anesthetic overdose of small rodents?
air tight container during the euth
once death is assumed, safe, active scavenge
open chamber & confirm death
perform secondary method to be sure
how is using CO2 anoxia as a method for small rodent euthanasia classified?
acceptable with conditions - use an induction chamber or mask/nose-cone
what is the flow rate used for CO2 anoxia as a method for small rodent euthanasia classified? what are some other requirements?
using 30-70% CO2 displacement rate
requires flow-meter & compressed gas cylinder
what animals cannot use CO2 anoxia as a method for small rodent euthanasia? why? what can you do instead?
neonates!!
highly CO2 resistant, > 50 minutes
IP anesthetic overdose or decapitation
T/F: dry ice to induce CO2 anoxia is an acceptable with conditions method of small rodent euthanasia
false - unacceptable
if you don’t have CO2, nose-cone/induction chamber, or access to anesthesia, what method can be used as a last resort for adult rats or smaller rates?
bell-jar method
what materials are needed for the bell-jar method?
liquid anesthetic
cotton ball
tea ‘ball’-type strainer
wide mouth, air tight plastic or glass jar
how is the bell-jar method performed?
place rodent in the jar first because anesthetic smell is highly aversive - place strainer holding anesthetic soaked cotton ball in
when are physical methods best used in rats & mice?
perform after heavy sedation/anesthesia
what are the patient requirements for cervical dislocation in rats & mice?
all post-weanling adult mice & rats that are 200g or less
why can’t cervical dislocation be used in rodents greater than 200 grams?
their nuchal ligament is too thick, so it’s not reliable
what should be palpated prior to cervical dislocation of rats & mice? what should be done after?
palpate C1-C2 separation
always use a secondary method
what physical method of cervical dislocation requires the most skill & is best suited for rats <200 grams & mice?
hemostats
what physical methods of cervical dislocation are the least likely to result in T13-L1 error?
stainless steel cage card holder & cervical dislocator
what physical method of cervical dislocation is best for mice?
stainless steel cage card holder
what physical method of cervical dislocation is best for rats?
cervical dislocator
how is microwave euthanasia classified?
research & mice only!!!!! pinpoint microwave irradiation to brain causing instantaneous death, used especially if stress of other euthanasia methods will mess up research
conditional, acceptable with conditions - due to human aversion
why is tricaine methanesufonate (MS-222) not preferred for zebrafish euthanasia?
too much time in the excitement phase
how long does tricaine methanesufonate (MS-222) take to work?
10-15 minutes - will see an excitement phase first
why should you never put tricaine methanesufonate (MS-222) in a secondary container?
family of cocaine! have the chemical paperwork on you!!!!
how is tricaine methanesufonate (MS-222) used?
dissolves in water but must buffer (bicarb) - no commercial drug prep, try to get ‘high’ & ‘pharma’ grade when possible
what is the preferred method of euthanasia for zebrafish?
rapid cooling ice bath
why is a rapid cooling ice bath the preferred method of euthanasia for zebrafish?
doesn’t affect histopathology - no ice crystals in tissue
near instantaneous death
T/F: it’s not a problem if a fish directly touches ice in an ice bath for euthanasia
false - don’t let them contact the ice
how is a rapid cooling ice bath used for euthanasia for zebrafish?
- fill a large secondary container with ice
- place a smaller, primary water bath into the secondary container
- let water temp equilibriate with the ice for about 20 minutes - don’t remove from the secondary container
- place the fish in the equilibrated ice bath (smaller container)
- fish should be lateral within 1-2 seconds, no operculum movement
what euthanasia methods for avian (non-poultry) are only used for small birds only?
cervical dislocation & decapitation
what euthanasia methods are used for avian (non-poultry)?
iv barbiturates & using a chamber for inhaled CO2 or inhaled anesthetics
what are some methods that can be used for euthanasia of rabbits & guinea pigs but are not preferred?
CO2 anoxia, cervical dislocation (if tiny), & penetrating captive bolt (rabbits, usu, meat)
what are the preferred methods of euthanasia for rabbits & guinea pigs?
inhaled anesthetic overdose & injectable barbiturates (IV > IP)
IP can be used for fractious or debilitated patients when you can’t get venous access
what are the 5 criteria given for AAEP for euthanasia justification?
- is the condition chronic, incurable, & the cause of inhumane pain & suffering?
- does the immediate condition present a hopeless prognosis for life?
- is the horse a hazard to itself or its handlers?
- will the horse require continuous medications for the relief of pain & suffering for the remainder of its life
- will the medical condition result in a lifetime of continued individual confinement
what justification is needed for euthanasia?
medical - not economic, considerations
regardless of age, sex, or potential value
what happens if you need to euthanize a horse & its owner is not present?
‘humane act necessary to relieve the animal’s pain & suffering’
get a concurring opinion from another veterinarian - ensure all parties are informed/consent: insurance, multiple owners
what is euthanasia defined in the critical thinking lecture?
rapid loss of consciousness followed by cardiac or respiratory arrest and the ultimate loss of brain function
minimize distress & anxiety
non-functional cerebral cortex = no pain
what are the major safety considerations to think about in euthanizing large animals?
animals falling when general anesthesia is induced
animals thrashing after euthanasia is injected
what is the definition of acceptable in regards to euthanasia methods?
consistently produce a humane death when used as the sole method
what is the definition of acceptable with conditions in regards to euthanasia methods?
require certain conditions to be met to consistently produce humane death, greater potential for operator error, aren’t well documented, or require a secondary method to ensure death
what is the definition of unacceptable in regards to euthanasia methods?
inhumane under any conditions or unsafe to the operator
what is the definition of loss of unconsciousness in animals?
loss of righting reflex
after loss of consciousness in an animal, what may be seen?
convulsions, vocalizations, reflex struggling, breath holding, & tachypnea
what is the order of mechanism when using barbiturate overdose as a method of euthanasia in horses?
CNS depression - loss of consciousness - anesthesia - apnea - cardiac arrest
what are the advantages of using barbiturate overdose?
rapid action, minimal discomfort, & relatively inexpensive for horses
what are the disadvantages of using barbiturate overdose?
requires IV access, expensive for cattle, restraint, controlled drug (schedule II or III), terminal gasp, & drug persists in carcass (residues persist for over 1 year)
what is the dose needed for euthanasia solution?
1ml/10 pounds
what should happen/be done immediately after iv barbiturate injection in horses?
horse should collapse & have a brief period of muscle contraction that may be violent followed by a slow relaxation
confirm death within 5 minutes - dilated/unresponsive pupil, no corneal reflex, no breathing, & no heart beat
what are the conditions that must be met for gunshot as a method of euthanasia?
marksmanship, always prepared to use a 2nd shot, & knowing how landmarks differ between horses, cattle, sheep, goats, & swine
what are the conditions that must be met for captive bolt as a method of euthanasia?
requires restraint because the bolt must rest on the head
T/F: gunshot & captive bolt may be followed with secondary methods such as exsanguination
true
what is the goal of using gunshot as a euthanasia method?
penetration & destruction of brain tissue without emergence from the contralateral side of the head
what are the disadvantages of using gunshot as a euthanasia method?
ricochet & aesthetics
what is the goal of using captive bolt as a euthanasia method?
gunpowder or compressed air provides power to penetrate the skull - concussion & trauma to the cerebral hemisphere resulting in an instantaneous brain death
T/F: non-penetrating captive bolts on stun the animal
true
what type of captive bolt gun is this?
schermer
what type of captive bolt gun is this?
cash
what is conditional defined as in conditionally acceptable secondary methods of euthanasia?
require general anesthesia prior to euthanasia
what are 5 examples of conditionally acceptable methods of euthanasia covered for large animals?
- exsanguination
- potassium chloride
- magnesium sulfate
- intra-thecal lidocaine
- succinylcholine
how do potassium chloride & magnesium sulfate cause euthanasia?
stop the heart first, so respiratory centers will result in gasping of the animal - this is why general anesthesia is needed prior
what drugs can be used to induce general anesthesia prior to euthanasia?
xylazine, +/- diazepam or midazolam & ketamine
why should you leave the IVC in the animal if using potassium chloride to euthanize?
the blood doesn’t clot & it turns bright red
what is the advantage of using intrathecal lidocaine as a euthanasia method?
no residues
what is the disadvantage of using intrathecal lidocaine as a euthanasia method?
requires knowledge of atlanto-occipital CSF tap
how is intrathecal lidocaine given to induce death?
animal is anesthetized
atlanto-occipital joint is tapped & 60 mls of CSF fluid is removed
injection of 60-100 mls of lidocaine 2% is given
why is succinylcholine unacceptable by itself?
causes muscle paralysis but not loss of consciousness
when is succinylcholine used? how is it performed?
special situations - fractious or uncontrolled animal (rabies suspect)
injection given IV or IM & euthanize as soon as animal is down
what are 3 methods that are unacceptable for euthanasia?
- succinylcholine by itself
- chloral hydrate
- electrocution
what should be checked for confirmation of death?
respiration, pulse, auscultation, & lack of corneal reflex
T/F: a landfill may not accept a body for disposal if it was performed with chemical euthanasia
true
what is composting? how long does it take?
sanitary decomposition of organic materials by bacteria as a means of disposal of a body
takes 9-10 months
what are the requirements for burying a body after euthanasia?
verify with the county!!!
3-4 feet dirt cover, 100 yards from water, 7 feet wide & 9 feet deep
what is rendering as a means of disposal? what is required?
carcass is heated to destroy pathogens & produce usable end products (meat, bone, blood meal)
no barbiturates
how is biodigesting used as a means of euthanasia disposal?
use of alkaline hydrolysis at high temperatures to solubilize tissues - neutral solution of amino acids, peptides, sugars, & soap that can go to the landfill or sewer
what is the effect of recent strenuous exercise on drug dosing for euthanasia?
increased dose is required
if you don’t have access to jugular veins, what are some other ways to gain parenteral access for drug administration in horses?
facial vein, cephalic vein, superficial thoracic vein, & saphenous vein
