44 – Euthanasia

Question 1

What are the euthanasia AVMA classifications?

Answer 1

• Acceptable
• Acceptable with conditions
• Unacceptable

Question 2

What makes it an acceptable method? (criteria)

Answer 2

• Consent
• Pain free
• Limit stress
• Safety
• Quick
• Reliable
• Effective: loss of consciousness followed by death
• Irreversibility
• Emotional effect
• Environmental impacts
• *12 criteria in total

Question 3

Ideal euthanasia: order we want things to be in (process that are occurring in the body)

Answer 3

1. Depression of neurons necessary for life function: loss of consciousness (can include anesthesia)
2. Hypoxia: cardiac and respiratory arrest
3. Physical disruption of brain activity and destruction of neurons necessary for life: LOSS OF BRAIN FUNCTION

Question 4

What are the options for how to do euthanasia?

Answer 4

• Chemical: inhalant, non-inhalant
• Physical

Question 5

What are the inhalant agents for euthanasia?

Answer 5

• Isoflurane (irritating)
• Halothane, sevoflurane (non-noxious odour)
• NO increase to speed of onset
• CO: acceptable
• CO2: controversial (acceptable w/conditions)

Question 6

Inhalant agents: important things to remember/consider

Answer 6

• Chamber method <7kg
  o Container needs to be large enough to prevent hypoxia
• If can’t get a vein in
• If no injectables available
• Sometimes if during surgery you decide
• Downside: human exposure
• FAST
• Confirmation of death required (heartbeat, breathing, touch cornea and pupils)
• NOT appropriate for reptiles, amphibians, diving birds and mammals (can HOLD THEIR BREATH FOR A LONG TIME)

Question 7

CO and CO2

Answer 7

• Used for dogs/cats in some humane societies and for rodents and birds
• *Species dependant aversion

Question 8

CO

Answer 8

• Acceptable
• Signs of agitation, convulsions, muscle spasms, vocalization (can be difficult for the humans involved)
• Source is important (from a tank, not a CAR!)
• Blocks O2 uptake by RBCs

Question 9

CO2

Answer 9

• Hyperventilate and get acidosis (pain from carbonic acid)
• Breathlessness: panic
• Direct simulation of amygdala: fear response
• 7.5% increases pain threshold (takes time to get there)
• Need 30% to get anesthesia and then followed by death
• *Acceptable with conditions
• Gradual fill recommended
• Ex. used in avian species for depopulation

Question 10

What are non-inhalant methods of euthanasia?

Answer 10

• Barbiturates
  o Pentobarbital
• T-61
• Tricaine methane sulfonate (MS-222)

Question 11

Pentobarbital: things to know or consider

Answer 11

• Rapid, smooth
  o Possible excitement and agonal gasp
  o Consider adding propofol (or other sedation): premed
• Controlled drug
• Must be given IV
• Confirmation of death required
• Risk of scavenging (wildlife, bald eagles and dumps!)

Question 12

Barbiturates in birds and reptiles

Answer 12

• Most birds anesthetized first otherwise a massive excitement phase
• Reptiles: consider 2-3 days before releasing to owner, intracoelomic acceptable
  o 3 chamber heart (difficult on a good day to hear them)
  o Can slow heart for extended period of time
  o *GOOD TO USE: loss of eye pressure!

Question 13

T-61

Answer 13

• Contains
  o Local anesthetic
  o General anesthetic
  o Neuromuscular blocking agent
• NOT a controlled drug
• *AVMA acceptable, CCAC not recommended

Question 14

What are the concerns with T-61?

Answer 14

• Improper administration (IV only)
• Pain with administration
• Mammals
  o Dysphoria if injected too quickly
  o Respiratory paralysis (suffocation) BEFORE loss of consciousness
• Birds:
  o *does work: Anesthesia immediate + EEG loss <6 secs

Question 15

Pentobarbital for horses

Answer 15

• IV required
• Sedation or anesthesia recommended (NOT required)
• Risk to scavengers
• *used often

Question 16

Intrathecal lidocaine AFTER anesthesia in horses

Answer 16

• Longer respiratory, cerebral, brainstem and CV arrest compared IV barbiturates
  o Block all neurotransmission out of CNS
• Audible heartbeat 5mins vs. <1min
• EEG 2 min vs. 20s
• Sedation required
• *doesn’t matter that it takes longer as they are sedated
• Little risk to scavengers (placed in the intrathecal space which is protected by SC)

Question 17

Tricaine methane sulfonate (MS-222)

Answer 17

• *Suitable for fish and most amphibians
  (if normal for them, need to have access to air until unconsicous)
• Sodium bicarb required to buffer (very acidic on its own)
• IMMERSION (terrestrial reptiles should not be fully immersed)
• NOT controlled drug
• Used as an anesthetic
  o Increased concentration and prolong exposure
• Some reptiles intracoelomic (AVMA vs. unacceptable CCAC)
• Secondary method required to ensure death

Question 18

What are the unacceptable agents of euthanasia?

Answer 18

• Strychnine, nicotine, caffeine, cleaning agents, pesticides, disinfectants
• Magnesium sulfate, potassium chloride, NM blocking agents

Question 19

What are the physical methods for euthanasia?

Answer 19

• Captive bolt
• Gunshot
• Cervical dislocation
• Decapitation
• Acceptable with conditions
  o Electrocution
  o Kill traps
  o Thoracic compression
  o Exsanguination
  o Pithing
• *training and skill is CRITICAL

Question 20

Penetrating captive bolt

Answer 20

• Ruminants, horses, swine, lab rabbits, dogs, birds
• Concussion and trauma to cerebral hemisphere and brainstem
• Adequate restraint is important to ensure proper placement of captive bolt

Question 21

Cervical dislocation

Answer 21

• Rodents
• Birds

Question 22

Decapitation

Answer 22

• Rodents for tissue collection
• Wildlife

Question 23

Koechner euthanizing device

Answer 23

• Squeezes across next and does cervical dislocation
• Longer to death than regular cervical dislocation (more crushing vs. separation)
• Cervical vertebrae fractures

Question 24

Euthanasia by a blow to the head

Answer 24

• Acceptable for neonatal animals with thin craniums
  o Neonates, young piglets, small birds
• Single sharp blow delivered to central skull bones with sufficient force can produce immediate depression of CNS and destruction of brain tissue

Question 25

Gunshot

Answer 25

• Should only be performed by highly skilled personnel trained in use of firearms
• Legal requirements
• Personnel, public and nearby animal safety essential
• *NOT between the eyes: ’x’ between ears and eyes: shot in center of it
  o Hard to have correct trajectory
• Horse: go from the side (brainstem is at ‘base’ of ear)

Question 26

Exsanguination should only be considered when (AVMA)

Answer 26

• Animal is unconscious
• BUT: in emergency (ex. mare eviscerated=need to shorten time to death)

Question 27

Cardiac puncture

Answer 27

• Not acceptable in a conscious animal
• BUT: emergency (ex. deer with only 1 leg=can’t get IV in)