Date: May 2001
Reference:   Administrative Panel on Laboratory Animal Care

DIRECTIONS: Review the following material. Keep copies of guidelines with applicable protocols. You may find it helpful to post a copy of these guidelines in your laboratory. Questions should be forwarded to the A-PLAC office, 723-4550.

TRAINING: Training in these techniques and the humane treatment of laboratory animals during the procedures is taught by the Veterinary Service Center (VSC) staff. All new personnel who will be performing these techniques should contact VSC staff for training (723-6735).

These guidelines have been written to assist Directors in complying with AVMA recommendations as well as to apprise them of effective techniques for rodent euthanasia.

I. Background

The A-PLAC is specifically charged with reviewing the methods of euthanasia for each research protocol to assure compliance with the recommendations contained in the Report of the AVMA Panel on Euthanasia (J. Am. Vet. Med. Assoc. 2000; 218: 669 - 696). Since physical methods of euthanasia (such as cervical dislocation) require the most skill to perform and are most likely to be affected by human error, the AVMA Panel recommends that such methods are used only when alternative methods are not appropriate. Methods deviating from these recommendations must be "justified for scientific reasons in writing by the investigator."

The use of cervical dislocation in rodents is only recommended for mice and small rats, and whenever possible the use of sedation or light anesthesia prior to euthanasia is recommended. The AVMA Panel report recognized that there may be special circumstances or situations involved with research animal euthanasia, and institutional animal care and use committees have been given the authority to consider which other means may be acceptable.

II. Training Requirements

The A-PLAC reviews all protocols using physical techniques to assure that personnel performing the procedures are appropriately trained. The primary responsibility for establishing and monitoring this training lies with the protocol director. Before using physical methods, inexperienced persons should be trained by experienced persons and should practice on carcasses or anesthetized animals to be euthanatized until they are proficient in performing the method properly and humanely. The staff of the Veterinary Service Center (VSC; 723-3876) is available upon request to provide this training to personnel listed on approved protocols.

III. Acceptable Use

Use of cervical dislocation to euthanize mice and rats with body weights <200g by trained personnel is appropriate (upon A-PLAC approval) if any of the following is true:

1. Animals are sedated or anesthetized using drugs or carbon dioxide prior to cervical dislocation
   
   - or -
   
   
2. PD has considered other methods, and has determined that cervical dislocation without the use of other agents is the most appropriate method based on previous experience using this technique and/or the specific aims of the study.
   
   

IV. Method

Before using the technique of cervical dislocation it should be practiced on anaesthetized mice until the operator is competent.

1. Restrain the rodent in a normal standing position on a firm, flat surface and grasp the tail with one hand.
   
   
2. Place a stick-type pen, a rod-shaped piece of wood or metal, or the thumb and first finger of the other hand against the back of the neck at the base of the skull.
   
   
3. To produce the dislocation, quickly push forward and down with the hand or object restraining the head while pulling backward with the hand holding the tail.
   
   

Performing the procedure on a surface that the animal can grip may make it easier to gain access to the base of the skull because rodents often stretch themselves forward when held by the tail. The effectiveness of dislocation can be verified by separation of cervical tissues. When the spinal cord is severed. a 2-4 mm space will be palpable between the occipital condyles and the first cervical vertebra. Occasionally, however, the dislocation occurs between thoracic vertebrae. Check closely to confirm respiratory arrest, and when possible verify, by palpation, that there is no heart beat.