Methods of euthanasia in experimental animals MCQs With Answer

Introduction:

Euthanasia of experimental animals is the humane ending of life to prevent pain or distress, following ethical and legal guidelines. B.Pharm students must understand methods of euthanasia in experimental animals, including chemical methods (barbiturate overdose, inhalational agents like CO2 or isoflurane), physical methods (cervical dislocation, decapitation, captive bolt), species-specific considerations, routes and dosages, and confirmation of death. Knowledge of animal welfare regulations, AVMA recommendations, analgesia/anesthesia requirements, and the 3Rs (Replacement, Reduction, Refinement) is essential. This topic links pharmacology, toxicology, and lab animal science to ensure competent, humane practice. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the most accepted definition of euthanasia in experimental animals?

• A procedure that hastens death regardless of animal suffering
• A humane procedure to induce rapid death with minimal pain and distress
• A method to immobilize animals for prolonged experiments
• An approach to reduce experimental variability

Correct Answer: A humane procedure to induce rapid death with minimal pain and distress

Q2. Which chemical agent is most commonly used for euthanasia by intravenous overdose in laboratory mammals?

• Sodium pentobarbital
• Potassium chloride
• Isoflurane
• Chloroform

Correct Answer: Sodium pentobarbital

Q3. What is a primary disadvantage of using CO2 for euthanasia in rodents?

• It is painless and rapid for all species
• It may cause distress or aversive behavior before loss of consciousness
• It requires intravenous administration
• It leaves toxic residues in tissues

Correct Answer: It may cause distress or aversive behavior before loss of consciousness

Q4. Which physical method is recommended for euthanasia of neonatal mice by many guidelines when performed by trained personnel?

• Cervical dislocation
• Decapitation with guillotine
• Intraperitoneal pentobarbital
• Captive bolt

Correct Answer: Cervical dislocation

Q5. Which route of pentobarbital administration is commonly used for euthanasia in small rodents when IV access is difficult?

• Oral gavage
• Intraperitoneal (IP) overdose
• Subcutaneous infusion
• Topical application

Correct Answer: Intraperitoneal (IP) overdose

Q6. What is the role of anesthesia before euthanasia with a secondary physical method?

• To increase experimental variability
• To minimize pain and distress prior to the physical procedure
• To delay the euthanasia process intentionally
• To make animals more resistant to euthanasia

Correct Answer: To minimize pain and distress prior to the physical procedure

Q7. Which of the following is considered an unacceptable sole method of euthanasia in many species due to pain and prolonged suffering?

• Immediate IV pentobarbital
• Cervical dislocation by trained personnel
• Gassing with sodium nitrite
• Asphyxiation by lack of oxygen without anesthesia

Correct Answer: Asphyxiation by lack of oxygen without anesthesia

Q8. How should death be confirmed after euthanasia?

• Assume death based on time elapsed
• Check for absence of heartbeat, respiration, and corneal reflex
• Wait for rigor mortis only
• Rely on color change of fur

Correct Answer: Check for absence of heartbeat, respiration, and corneal reflex

Q9. Which method is commonly used for euthanasia of adult birds in research settings?

• Intraperitoneal pentobarbital only
• Cervical dislocation or intravenous overdose after anesthesia
• CO2 chamber without pre-anesthesia in all cases
• Topical anesthetic application

Correct Answer: Cervical dislocation or intravenous overdose after anesthesia

Q10. Potassium chloride is sometimes used as a secondary euthanasia method. What is required before its use?

• No prior steps; it is painless alone
• Prior anesthesia to ensure unconsciousness
• Administration by oral route
• Use only in conscious animals to ensure rapid cardiac arrest

Correct Answer: Prior anesthesia to ensure unconsciousness

Q11. Which inhalational agent is considered acceptable for euthanasia of small mammals when used correctly?

• Nitrogen without monitoring
• Isoflurane followed by CO2 if needed
• Chlorinated solvents like chloroform routinely
• Ammonia gas exposure

Correct Answer: Isoflurane followed by CO2 if needed

Q12. For which species is decapitation (guillotine) commonly accepted when performed by trained staff?

• Large livestock like cattle
• Small rodents and some small mammals
• Aquatic fish only
• Wild ungulates in the field

Correct Answer: Small rodents and some small mammals

Q13. What is an important pharmacological consideration when using pentobarbital for euthanasia in food-producing animals?

• It leaves no drug residues and is always allowed
• It can result in tissue residues making carcasses unsuitable for human or animal consumption
• It is ineffective in large animals
• It causes immediate tissue contamination with heavy metals

Correct Answer: It can result in tissue residues making carcasses unsuitable for human or animal consumption

Q14. According to humane euthanasia principles, what should be minimized during the process?

• Human oversight and documentation
• Time, pain, fear, and distress experienced by the animal
• Use of analgesia
• Pre-euthanasia sedation

Correct Answer: Time, pain, fear, and distress experienced by the animal

Q15. Which method is commonly recommended for euthanasia of fish to ensure rapid loss of consciousness?

• Rapid chilling (ice slurry) for all species
• An overdose of buffered MS-222 (tricaine methanesulfonate)
• Exposure to CO2 gas without buffering
• Electrical stunning only

Correct Answer: An overdose of buffered MS-222 (tricaine methanesulfonate)

Q16. What does the “secondary physical method” term refer to in euthanasia protocols?

• A sole chemical method without physical intervention
• A confirmatory physical procedure performed after a chemical method to ensure death
• An initial sedation protocol
• Use of environmental enrichment during euthanasia

Correct Answer: A confirmatory physical procedure performed after a chemical method to ensure death

Q17. Which guideline body provides widely referenced recommendations on laboratory animal euthanasia?

• World Health Organization (WHO)
• American Veterinary Medical Association (AVMA)
• International Monetary Fund (IMF)
• World Trade Organization (WTO)

Correct Answer: American Veterinary Medical Association (AVMA)

Q18. Which of the following is a contraindication to using CO2 euthanasia in some small animals?

• Species that tolerate CO2 with no aversion
• Animals with respiratory compromise where stunning is preferred
• Animals already under deep anesthesia
• Using CO2 at recommended flow rates

Correct Answer: Animals with respiratory compromise where stunning is preferred

Q19. Why is proper training and competency essential for personnel performing physical euthanasia methods?

• Because unskilled personnel reduce animal welfare risks
• To ensure rapid, effective, and humane application and to avoid prolonged suffering
• To increase procedural variation for experiments
• To allow use of unapproved methods

Correct Answer: To ensure rapid, effective, and humane application and to avoid prolonged suffering

Q20. Which sign is NOT a reliable indicator of death immediately after euthanasia?

• Absence of heartbeat
• Fixed, dilated pupils
• Absence of spontaneous respiration
• Immediate onset of rigor mortis

Correct Answer: Immediate onset of rigor mortis

Q21. In toxicology studies, why must euthanasia methods be chosen carefully?

• They never interact with study endpoints
• To avoid interference with tissue chemistry and study results
• Because method choice is irrelevant to pharmacokinetics
• To maximize residue deposition

Correct Answer: To avoid interference with tissue chemistry and study results

Q22. What is the recommended approach if IV access fails for euthanasia in a larger animal?

• Use intramuscular injection of barbiturate at low dose
• Use alternative approved routes or a combination of sedation followed by physical method
• Delay euthanasia indefinitely
• Use oral pentobarbital

Correct Answer: Use alternative approved routes or a combination of sedation followed by physical method

Q23. Which consideration is most important when choosing a euthanasia method for neonatal animals?

• Cost of the method only
• Age, size, brain maturation, and guideline recommendations
• Ease for personnel ignoring welfare
• Availability of inhalational chambers only

Correct Answer: Age, size, brain maturation, and guideline recommendations

Q24. What is the main ethical framework often referenced in laboratory animal work that influences euthanasia decisions?

• The Four Pillars of Medicine
• The 3Rs: Replacement, Reduction, Refinement
• The Hippocratic Oath only
• Cost–benefit economic analysis alone

Correct Answer: The 3Rs: Replacement, Reduction, Refinement

Q25. What safety concern is associated with inhalational anesthetic agents during euthanasia?

• They produce no occupational hazards
• Risk of human exposure and need for scavenging systems
• They cannot render animals unconscious
• They always leave harmful residues in tissue

Correct Answer: Risk of human exposure and need for scavenging systems

Q26. Which method is rapidly effective and commonly used for euthanasia of larger livestock under field conditions?

• Inhalational isoflurane chambers
• Penetrating captive bolt followed by exsanguination or pithing
• Intraperitoneal pentobarbital only
• CO2 chambers for cattle

Correct Answer: Penetrating captive bolt followed by exsanguination or pithing

Q27. Which statement about pentobarbital euthanasia is correct?

• It causes immediate tissue fixation unsuitable for histology
• It produces rapid central nervous system depression leading to respiratory arrest when given in overdose
• It is ineffective in inducing unconsciousness
• It should always be given orally for speed

Correct Answer: It produces rapid central nervous system depression leading to respiratory arrest when given in overdose

Q28. What documentation is essential after performing euthanasia in a laboratory facility?

• No records are required
• Species, method, dose/route, personnel, time, and reason for euthanasia
• Only the name of the person performing it
• Only the disposal method

Correct Answer: Species, method, dose/route, personnel, time, and reason for euthanasia

Q29. Which method is often discouraged for routine euthanasia of small mammals due to potential pain and variability?

• Intravenous pentobarbital overdose
• CO2 at appropriate fill rates with preconditioning
• Blunt force trauma without prior anesthesia
• Decapitation by trained staff

Correct Answer: Blunt force trauma without prior anesthesia

Q30. What is the correct immediate action if an animal shows signs of consciousness after a euthanasia attempt?

• Assume death and proceed with disposal
• Perform an immediate, approved secondary method or re-administer an appropriate agent to ensure death
• Wait for spontaneous cessation of signs
• Document and leave the animal unattended

Correct Answer: Perform an immediate, approved secondary method or re-administer an appropriate agent to ensure death

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