Euthanasia of Rodents

The University of ChicagoAnimal Resources Center

Warning!

If you are reviewing this for credit as part of the IACUC requirement for Rodent Euthanasia Training please go to: https://iacuc.uchicago.edu/resources.shtml

The slides in this module do not contain the quiz which is needed for enrollment. The information in this module is intended as reference material and is the same as in the AALAS Learning Library, but with additional information and formatting.

Goals of the Session1) Describe the common methods used for euthanasia

of rodents at this institution

2) Describe how to perform euthanasia on rodents

3) Describe the steps and methods to confirm an animal is dead prior to disposal

4) Emphasize the importance of performing these techniques completely and appropriately to prevent pain and distress to the animal.

Euthanasia

Euthanasia derives from the Greek eu meaning good, and thanatos meaning death.

A "good death" occurs with minimal pain and distress.

It is your responsibility to understand how to appropriately euthanatize the animals you work with so that it is done humanely.

If you do not know how to perform these procedures seek training!

Training may be from the Principal Investigator or ARC!

EuthanasiaAnimals can recover from insufficient administration of an injectable or inhalational euthanasia agent.

Therefore, it is essential that euthanasia be performed correctly and that death be confirmed prior to disposing of an animal.

Imagine what it would feel like to wake up in a sealed plastic bag inside a freezer only to slowly suffocate and freeze to death.

Acceptable Euthanasia Methods

CO2 overdose followed by confirmation of death and a secondary method of euthanasia.

Inhalant anesthetic overdose followed by confirmation of death and a secondary method of euthanasia.

Injectable anesthetic overdose or injectable euthanasia agent followed by confirmation of death and a secondary method of euthanasia.

Conditionally Acceptable Methods

Common physical methods are Conditionally Acceptable including:

Cervical Dislocation without anesthesia

Decapitation without anesthesia

The conditions that make these acceptable are: A statement of Scientific Justification and approval by IACUC.

Justification is necessary because these methods have the potential to cause pain and distress and therefore are only allowed based on the scientific need of the study.

Conditionally Acceptable Methods

Appropriate training is of the highest importance

Individuals who will perform these procedures need to demonstrate proficiency in the technique to an ARC veterinarian as a condition of IACUC approval

Confirmation of Death

With many euthanasia methods, an animal may give the appearance of being dead, (i.e. lack of movement or respirations) but return to consciousness.

Therefore death must be confirmed.

Since lack of movement cannot be used to confirm death a confirmatory secondary physical method must be performed.

The University of Chicago IACUC requires an adjunctive method be used to ensure death in rodents.

Acceptable Secondary Euthanasia Methods

Cervical DislocationDecapitationOpening the chest cavity to create a bilateral

pneumothoraxExsanguination – bleeding outVital organ removal – e.g. brain, heart, etc.

Carbon Dioxide

Carbon dioxide works by inducing hypoxia (lack of oxygen to cells) in the animal, which results in death.

Carbon dioxide must be delivered from compressed gas cylinders, not from dry ice, or other means.

The CO2 chamber must not be overcrowded with mice. - Capacity limits are listed on the chamber.

- It is best to not mix cages of mice since this could be distressful.

The person performing the procedure must stay with the animals during the procedure. Leaving the room during the euthanasia procedure may jeopardize the welfare of the animals if a problem develops.

CO2 Euthanasia Procedure

1. Place the animals into the CO2 chamber, or alternatively place the entire cage into the chamber with the lid removed

2. Follow the directions on the CO2 chamber to initiate the flow of CO2 into the chamber.

3. Leave the animals in the chamber for 3-5 minutes or until lack of breathing and gross movement are observed.

4. Always perform a secondary method of euthanasia:Cervical dislocation, decapitation, opening the chest cavity, vital organ removal or exsanguination.

5. Always place the animals into a plastic bag, label with PI

name and date, then place into the morgue.

CO2 Euthanasia Demo

Gas Anesthetic Overdose Procedure

1. Isoflurane is the most common agent used, although sevoflurane is also an acceptable alternative.

2. Expose the animal to high concentrations of the gas anesthetic until lack of breathing and gross movement are observed.

3. Perform a secondary method of euthanasia:Cervical dislocation, decapitation, opening the chest cavity, vital organ removal or exsanguination.

4. Place the animals into a plastic bag, label with PI name and date, then place into the morgue.

Injectable Euthanasia Method

Pentobarbital or Pentobarbital-based euthanasia agents (e.g. Euthasol) are commonly used for injectable euthanasia.

Rodents should be administered 150mg/kg IP for euthanasia.

Perform a secondary method of euthanasia:

Cervical dislocation, decapitation, opening the chest cavity, vital organ removal or exsanguination.

Place the animals into a plastic bag, label with PI name and date, then place into the morgue.

Euthanasia of Neonatal RodentsThe neonates of rodents are generally resistant to the effects of hypoxia.

Euthanasia agents which act by way of hypoxia may cause significant delays in the onset of death. As a result, neonatal animals typically take longer to die than adults.

Therefore, methods of euthanasia which do not induce hypoxia, e.g., chemical or physical methods, are preferable for neonates.

For example, an inhalant agent could be administered to neonates for the purpose of inducing the loss of consciousness, and then another method (physical, such as decapitation) could be used to kill the animal.

Euthanasia of Neonatal Rodents

In rodents less than 10 days of age neonates may be euthanized by:

injection of chemical anestheticsdecapitation with surgical scissorscervical dislocation Immersion into liquid nitrogen or perfused with fixatives provided that they are anesthetized before performing these procedures.

In neonates greater than 10 days of age, pups may first be anesthetized with CO2 or injectable anesthetic and then must have a physical method performed.

IACUC Requirements

The Principal Investigator is responsible for assuring all members of laboratory are appropriately trained for the procedures described in the protocol.

The euthanasia method must be described in the protocol and only those methods described in the protocol may be used.

Each laboratory member who works with animals must know what procedures are approved in the IACUC protocol and must not perform any procedures prior to IACUC approval.

Compliance

The NIH Office of Laboratory Animal Welfare (OLAW) emphasized the importance of ensuring that euthanatized animals are really dead, and further stated that unintended recovery of animals after euthanasia represents: 1) serious noncompliance with the PHS Policy and 2) a serious deviation from the provisions of the Guide

for the Care and Use of Laboratory Animals.

Such incidents must be reported to OLAW by the IACUC with a full explanation of the circumstances and actions taken to prevent recurrence.

Summary

It is very important that you make sure an animal is really dead before placing it in a bag and disposing of the bag. It is easy to mistake a deeply anesthetized animal for a dead animal, and you do not want the animal to experience the terror of waking up in a closed bag and slowly suffocating to death.

Where to get additional Information

ARC Guidelines on Euthanasia http://arc.bsd.uchicago.edu

2007 AVMA Euthanasia Guidelines http://www.avma.org/issues/animal_welfare/euthanasia.pdf

IACUC

http://ors.bsd.uchicago.edu/IACUC/

AALAS Learning Library courses http://www.aalaslearninglibrary.org/default.asp

ARC veterinarians