Euthanizing Agents Flashcards
What is euthanasia?
ending the life of an individual animal in a way that minimizes or eliminates pain and distress by rapid loss of consciousness followed by loss of vital body function (respiration, heartbeat, brain)
What is the Panel on Euthanasia?
AVMA - convenes to evaluate methods and potential methods of euthanasia for the purpose of creating euthanasia guidelines for veterinarians by updating methods, techniques, and agents of euthanasia
How has the Panel on Euthanasia widened their scope throughout the years?
- 1963: methods and recommendations applicable to dogs, cats, and other small mammals
- 1972, 1978: laboratory and food animals
- 1986: poikilothermic, aquatic, fur-bearing wildlife
- 1993: horses and wildlife
What needs to be considered during euthanasia?
animal welfare and minimizing pain/distress
What pre-euthanasia procedure is required to minimize pain and distress?
proper handling - also ensures the safety of the person performing the euthanasia
- amount of control is dependent on the species, breed, and size of the animal
What behaviors after euthanasia administration should be communicated to the owner?
- vocalization
- agonal breaths
- muscle twitches
- failure of eyelids to close
- urination and defecation
What are the 3 basic mechanisms of euthanasia?
- direct depression of neurons vital for life functions
- hypoxia
- physical destruction of neurons and brain activity vital for life
What 14 criteria where considered for evaluating euthanasia in the 2020 Panel of Euthanasia?
- ability to induce loss of consciousness and death with minimum pain and distress
- time required to induce loss of consciousness
- reliability
- personnel safety
- irreversibility
- compatibility with intended animal use and purpose
- documented emotional effect on observers or operators
- compatibility with subsequent evaluations, examinations, or use of tissue
- drug availability and human abuse potential
- compatibility with species, age, and health status
- ability to maintain equipment in proper working order
- safety for predators or scavengeers
- legal requirements
- environmental impacts of disposition of remains
What is the caring-killing paradox? How can its effect be mitigated?
wanting to care for the animals you see, but needing to kill some of them for their own health
training personnel in the underlying justifications for euthanasia
Why are most euthanasia agents not used in human medicine? What are some examples?
most have a narrow therapeutic index or excessive side effects —> commonly used in suicide attempts
- Acepromazine
- Xylazine
- T-61
- Barbiturates
What is the preferred method for administering euthanasia solutions?
IV - most rapid, reliable
What dose of anesthetics can be used as a euthanasia solution?
3-4x therapeutic dose
What barbiturates is the most suitable IV euthanasia solution? What other 2 groups are used?
sodium pentobarbital
- barbituric acid derivatives (oxybarbiturates) - sodium pentobarbitone, secobarbital
- thiobarbiturates - thiopentone
What are the 4 advantages to using barbiturates as euthanasia solutions?
- speed
- induce euthanasia smoothly
- less expensive
- FDA approved - readily available
What is the mechanism of action of barbiturates? What happens at the high dose needed for euthanasia?
depresses CNS by interfering with sodium and potassium transport across the cell membranes, blocking postsynaptic transmission
bind directly to GABA, resulting in dose-dependent sedation, hypnosis, anesthesia, and respiratory depression
Why is the disposal of barbiturates and carcasses containing it important?
avoid poisoning scavenging wildlife
What are 7 disadvantages to used barbiturates as euthanasia solutions?
- IV injection required
- animal must be appropriately restrained
- federal drug regulations require strict accounting and must be used under supervision of personnel registered with the US DEA
- terminal gasp commonly occurs
- animals may go through an excitatory phase
- drug persists in remains
- tissue artifacts (splenomegaly) may occur
What is the preferred method of euthanasia for dogs, cats, horses, and other animals? What can be done if the preferred method of administration is not possible?
IV bartbituric acid derivative (sodium pentobarbitone, secobarbital)
intraperitoneal injection - if IV is distressful, dangeroud or difficult due to small patient size
When in intracardiac injection of barbiturates allows for euthanasia?
if the animal is unconscious or anesthesized
What is Tributane? What part of it has a strong narcotic effect? How does it act?
nonbarbiturate euthanasia agent containing Embutramide, chloroquine phosphate, and lidocaine
Embutramide (γ-hydroxybutyrate derivative)
causes respiratory depression in the CNS and induces sleep anesthesia
What other organ system does Embutramide in Tributane affect? What 3 effects cause death?
CVS
- hypotension
- myocardial depression
- ventricular dysrhythmias
What is Chloroquine phosphate? Why was it added to Tributane?
antimalarial drug —> shortens the time from unconsciousness to death (profound CVS depressant)
Why was Lidocaine added to Tributane?
reduces the pain associated with IV injection in cats
How does Tributane cause death? How should it be administered? Why does it need to be used carefully in cats?
CNS depression, respiratory depression, and hypoxia = circulatory collapse
IV
(extralabel) - agonal breathing may occur
What are 3 advantages to using Tributane?
- rapid onset
- induces anesthesia smoothly with minimal discomfort
- schedule III status makes it simpler to obtain, store, and administer compared to sodium pentobarbital (schedule II)
What are 5 disadvantages to using Tributane?
- not currently being manufactured
- IV injection
- animal must be appropriately restrained
- agonal breathing may occur
- remains in animal’s remains
What are the 3 agents found in T-61 (Tanax)? What are their mechanisms of action? In what 3 animals has use been described?
- Embutramide - anesthetic, narcotic
- Mebezonium iodide - nondepolarizing NMB
- Tetracaine hydrochloride - local anesthetic
- dogs: IV
- amphibians: dorsal lymph sac
– small birds: IM
What are 2 advantages to using T-61 (Tanax)?
- rapid onset (dogs, cats, horses, lab animals, birds, wildlife)
- terminal (agonal) gasps not observed
What 4 disadvantages are associated with T-61 (Tanax)?
- not currently manufactured
- slow IV injection required to avoid dysphoria prior to unconsciousness
- animal must be appropriately restrained
- secondary toxicosis may occur in animals that consume remains
Making a decision regarding euthanasia:
Evaluating morality:
