Euthanasia Flashcards
what is orthonasia
“ Right Death”, not artificially extend the dying process
what is unconsciousess
Loss of awareness (anesthesia or stunning).
Brain’s ability to receive an integrate information is disrupted
Difference between sedation and anesthesia
Animal is still arousable while sedated, whereas it shouldn’t be if anesthetized (or stunned)
what is depopulation
-Rapid destruction of several animals.
-Emergency (control infectious diseases, catastrophes…)
what is the definition of humane slaughter (4 parts)
-Process and methods to kill animals for commercial reason (food, fur…).
-Applies to both individual animals and large scale.
-Includes transport and handling before unconsciousness and death.
-Not all the slaughter methods meet criteria to be considered euthanasia
3 death mechanisms
-direct depression of neurons necessary for life funciton
-hypoxia
-physical disruption of brain activity
goals of euthanasia
- Achieve irreversible unconsciousness.
- Ideally brain first, followed by cardiac and respiratory arrest.
- Minimize pain, fear and anxiety
can neuromuscular blocking drugs be used on conscious animals
Neuromuscular blocking drugs should never be used in conscious animals
what does the perception of pain require
The perception of pain requires nerve impulses from peripheral nociceptors to reach a functioning conscious cerebral cortex and subcortical brain structures
what two things can happen during euthanasia that you need to warn the owner about
- Post-mortem twitching or movement: occur because the
muscles and nerves go through a short phase of hyperexcitability - Agonal breaths: gasping is a brainstem reflex in response to hypoxia, it is the last respiratory pattern prior to terminal apnea
three death mechanisms
-direct depression of neurons necessary for life function
-hypoxia
-physical disruption of brain activity
how do anesthetics produce unconsciousness
- Reducing information received by the cortical area
- Preventing integration
what does the process of direct depression of neurons lead to
Depression of cortical neuronal system leads to loss of consciousness, followed by respiratory and cardiac arrest.
when can we use inhalants for direct depression of neurons? what are some issues with using it?
- Useful for small animals (<7 kg) or difficult IV access
- Easy to administer (mask, chamber, gauze or cotton)
- Can be used in 2-step euthanasia (induction, followed by injectables)
- Animals may struggle (pungent odor) during induction, sedation helps
- Slow
- Challenging for food-producing animals due to potential for tissue residues
- Not practical for large animals
what are some options related to parenternal injection/topical application/immersion related to direct depression of neurons
- Barbiturates
- T-61: Mixture of embutramide, mebezonium, and tetracaine hydrochloride. Not in the US market, Slow IV injection is necessary to avoid dysphoria prior to unconsciousness
- MS-222 (immersion)
- Ultra potent opioids (IM, wildlife)
- Ketamine/a2 -adrenergic combinations
- Ethanol
what is the most common drug used for barbituates overdose for direct depression of neurons
sodium pentobarbitol
what is the preferred method of direct depression of neurons in domestic species
barbituate overdose
what normally happens with barbituate overdose? what can happen?
- Deep anesthesia progresses to apnea and cardiac arrest.
- Potent, fast, long acting, stable in solution, and inexpensive.
- Agonal breaths are common (sedation).
- FDA approved for dogs and horses.
- Can be irritant; IV preferred, IP and IC acceptable
how is hypoxia achieved
- Hypoxia is commonly achieved by exposing animals to high concentrations of gases that displace O2
- And/or impair oxygen transport by hemoglobin
when can we use CO2 for hypoxia? what can happen? what do we want to achieve and how?
-its acceptable with conditions
- CO2 may cause pain due to the formation of carbonic acid when it contacts moisture on the respiratory and ocular membranes
- Gas displacement rate is critical to the humane application of CO2
- If an appropriate gradual increase % is used, animals will lose consciousness before painful
what species can we use N2 and argon in? what species cant we use it in? how does it work
- Do not appear to be directly aversive to chickens, turkeys, and pigs and appear to reduce, but not eliminate, the behavioral responses to hypoxia
- O2 concentration of <2% unconsciousness in 90 sec, death in 3 min
- Unacceptable for other mammals
how does carbon monoxide work to induce hypoxia? what can it cause?
- Interferes with O2 uptake.
- Induces loss of consciousness without pain and with minimal discernible discomfort, depending on species (rodents, dogs and cats).
- Death occurs rapidly if concentrations of 4% to 6% are used (8-6 min).
- May cause convulsions, agitation and vocalization.
what are some physical methods of euthanasia
-captive bolt
-gunshot
-cervical dislocation
-electrocution
-exsanguination
what is stunning
Stunning is the process of rendering animals immobile or unconscious, with or without killing the anima
what are some pros of physical methods of euthanasia
- When properly used by skilled personnel with well-maintained equipment, physical methods of euthanasia may result in less fear and anxiety.
- In some species might be more rapid, painless, humane, and practical.
- Most of these methods are acceptable with conditions in some species only, required training and/or license
how do physical methods of euthanasia work
Destruction of midbrain centers that control cardiac and respiratory activity to cause “stunning” or death
bilateral vs unilateral physical methods of euthanasia
- Bilateral destructive lesion of the rostral pons:
- greatest extensor rigidity
- deepest coma or brainstem death
- pupils dilated and eyes unmoving
- Bilateral destruction of the medulla
results in respiratory arrest - Unilateral damage to medulla, pons or midbrain may result in short lived or incomplete cessation of responses
what species can we use captive bolt in
Ruminants, horses, swine, poultry, laboratory animals and dogs
what does captive bolt do and what is the most effective approach
- Concussion and trauma to the cerebral hemisphere and brainstem
- The most effective approach for an effective stun is a midline frontal
approach where the stunning projectile is directed towards the midbrain, pons and medulla oblongata
what method is only acceptable in anesthetized animals (2)
Potassium chloride and magnesium salts
Neuromuscular blocking agents
how do you confirm death?
- No pulse
- Inability to hear respiratory sounds and heartbeat by use of a stethoscope
- Lack of corneal reflex and response to firm toe pinch (deep pain)
- Graying of the mucous membranes and rigor mortis
what is the only situation where one sign can confirm death?
rigor motis (hours post death)
what areas can you use for companion animals if IV route isnt possible?
When IV route is not possible:
-Intraperitoneal (IP) in small animals
-Intra-organ: Intracardiac (IC), intrahepatic, intrarenal may be used only in unconscious animals (acceptable with conditions)
three unacceptable methods of euthanasia
-drowing, hypothermia, SQ/IM/intra-pulmonary/intrathecal in awake patients
what are some other accepted methods of euthanasia in companion animals that can be used when main options arent available or practicable (8)
- Injectable anesthetic overdose (eg. ketamine/xylazine)
- T-61
- Inhaled anesthetic overdose (eg, isoflurane, sevoflurane) only if <7 kg
- Carbon dioxide
- Gunshot (only in remote areas or emergency situations by skilled personnel)
- Penetrating bolt
- Electrocution using alternating current (under anesthesia)
- KCl (under anesthesia)
what methods of euthanasia can be used in equine (3)
Pentobarbital or a pentobarbital combination is the principal choice for equine euthanasia by chemical means
* Do not administer “off the needle”, catheter preferred
* If possible, under general anesthesia (xylazine 1 mg/kg + ketamine 2.5 mg/kg +/- diazepam 0.02 mg/kg)
Penetrating captive bolt or gunshot: appropriate restrain and only used by
well-trained personnel who are regularly monitored to ensure proficiency
Adjunct methods only after anesthesia: (1) KCl injected iv or intracardially;
(2) Magnesium sulfate injected iv; or (3) 60 ml of 2% lidocaine injected
intrathecally
when can you use neuromuscular blocking agents in equine
Neuromuscular blocking agent can be used if the horse or people could get injured before proper sedation/anesthesia (e.g. racehorse with a fracture)
It needs to be followed by an appropriate method of euthanasia as soon as the animal can be controlled
what are acceptable and acceptable with conditions methods of euthanasia in ruminants (2)
Acceptable
* Barbiturates: potential residues in animal remains, extra label in food
animals
Acceptable with conditions
* Penetrating captive bolt or gunshot: followed by an adjunctive method such as exsanguination, iv administration of potassium chloride or magnesium sulfate, or pithing to assure death
preferred method vs what is used in slaughter plants for swine euthanasia
-Overdose of barbiturates: preferred method in pet pigs.
-CO2 , Ar, N2 , gas mixtures: most used method in slaughter plants
what are acceptable and acceptable with conditions methods of euthanasia in poultry (many)
Acceptable: overdoses of injectable anesthetics (not for meat consumption)
Acceptable with conditions:
- Inhaled gases: carbon dioxide, carbon monoxide, nitrogen or argon,
reduction of atmospheric pressure
- Physical methods:
* Cervical dislocation, decapitation
* Manually applied force trauma
* Electrocution (follow by a secondary method)
* Gunshot: free-ranging poultry and ratites when capture or restraint
* Captive bolts (penetrating or nonpenetrating)
other methods of euthanasia in swine (4)
- Gunshot.
- Non penetrating and penetrating captive bolts.
- Electrocution: head-to-heart configuration (fibrillation) or followed by secondary method.
- Blunt force trauma (in suckling piglets only >5kg)
what are acceptable and acceptable with conditions methods of euthanasia in amphibians and reptiles, and unacceptable
Acceptable
-Pentobarbital (IV, IC)
-MS-222 bath
Ideally confirmed by adjunctive method (decapitation, pithing)
Acceptable with Condition
-Inhalant, blunt trauma.
Hypothermia is unacceptable (except <4 g, in liquid N2)
what is the concern with disposing animals that were euthanized with barbituates
risk of environmental toxicity, may result in the illness and death of
scavenging/domestic animals animals
recommendations for disposal of euthanized animals (7)
- Incinerate or cremate animal remains whenever possible
- Immediately bury deeply according to local laws and regulations
- Securely cover or store animal remains if the ground is frozen
- Review and modify local landfill practices to prevent access of scavengers to legally
disposed animal remains - Educate clients about proper disposal
- Include a warning regarding disposal of animal remains on the euthanasia consent form
- Tag animal remains and outer bags or containers with prominent poison tag
