Lecture 4- Large Animal Euthanasia Flashcards
What are the musts of euthanasia
Must relieve fear and apprehension, must induce unconsciousness as rapidly as possible, ensuring minimum pain and suffering
What is the order of events in euthanasia
- Sedation/tranquilization
- Unconsciousness
- Cardiorespiratory arrest
What are the modes of action for euthanasia
Hypoxemia, depression of neurons vital for life, physical damage to brain tissue
What are reasons for large animal euthanasia
Food production, pain and suffering, intractable conditions/situations, chronic incurable conditions
How to determine when it is time
Chronic and incurable
Poor prognosis
Animal hazard to self or handler
Constant pain relieving medications for rest of life
What are approved methods of euthanasia
Injectable barbiturates
Captive bolt
Gunshot
Potassium chloride while anesthetized
How do injectable barbiturates work
Cause CNS depression
Death occurs from respiratory arrest and myocardial hypoxia
What are some examples of injectable barbiturates for euthanasia and what is the dose
Pentobarbital 100mL IV
Thiopental 20-30mg/kg
When is a captive bolt used
When tissues must be free of drug residues
How does captive bolt euthanasia work
Produces unconsciousness followed by exsanguination
What are the three types of captive bolts
Penetrating, non-penetrating, free bolt
How does a penetrating captive bolt work
Penetrates skull, catastrophically damages the cerebrum and part of cerebellum
Causes destruction of vital centers of brain, increase ICP and animal loses consciousness
What is the most effective captive bolt mechanism
Penetrating captive bolt- destroys brain matter while also leaving brain stem intact thus ensuring heart continues to pump during exsanguination
What is a disadvantage of penetrating captive bolt
Brain matter is allowed to enter the blood stream and possibly contaminating the other tissue
What causes unconsciousness in non-penetrating captive bolt
Bolt strikes forehead with great force causing concussion
What are the pro’s and con’s of the non-penetrating captive bolt
Pro- less likely to spread brain matter into blood stream, concerns about mad cow disease (BSE)
Con- less reliable at causing immediate and permanent unconsciousness
When is a free bolt used
Emergency, in the field euthanasia of large farm animals that can’t be restrained
Free bolt is only capable of firing when
Firmly pressed against a surface- typically animals forehead
Where should captive bolt be placed on head and what structures do we need to avoid
Placed on midline of forehead, 1/2 inch above eye level. Want to go through thinnest part of frontal sinus
What caliber is used in gunshot
32
Where should gunshot NOT be placed on horse
Between the eyes
How much potassium chloride is injected for euthanasia
50-100mL
What is the mechanism of death caused by potassium chloride
Cardiac arrest and tissue hypoxia
When is potassium chloride approved to be used
Unconscious or anesthetized
