Online First

2021 : Volume 1, Issue 1

Modified Cervical Dislocation, A Better Way in Laboratory Rat Euthanasia

Author(s) : Zeyi Cheng 1

1 Department of Cardiovascular Surgery , Sichuan University , China

Mod J Med Biol

Article Type : Editor Note

Abstract

Killing experiment animals is an unpleasant task in scientific research, and it is must be done as humanely as possible. Although there are many known methods to kill rats, researchers who study animal welfare and euthanasia are increasingly worried that the widely used technology is not the most painful and stressful the smallest. We aimed to introduce a more safe, efficient, and environmentally friendly method named modified cervical dislocation to kill the rats abandoned after the experiment.

Key words: Euthanasia; Rat; Modified Cervical Dislocation

Introduction

Rats are the most important and commonly usedexperimental animals in biomedical research; they havemade great contributions and sacrifices to our scientificresearch activities. Therefore, during the experiment, weshould abide by animal ethics and treat them well. After theexperiment, we should properly put them to death.

As bioscience and medical research workers, we mustkill rats after the experiment, but which method should wechoose? There are currently several ways to kill rats [1].

Cervical Dislocation

Grasp the tail of the rat with your right hand and pull it backward, while holding down the head of the rat with the thumb and index finger of your left hand, pull off the spinal cord and the brain, and the rat will die immediately, which causes rapid death, but skill must be learned and well grasped, otherwise, you can be bitten by them, I observed that many my colleagues/classmates are afraid to grab the rat with their hands, and then send the cervical dislocation to kill the rat.

Decapitation

The experimenters put on cotton gloves, hold the head of the rat with your right hand, and hold the back with your left hand, exposing the neck, the assistant uses scissors to cut off the head of the rat with scissors. It is a useful method when tissues must be free of euthanasia chemicals.

Hitting

Grab the tail of the rat with the right hand and lifted it and slammed it on the head, the rat died immediately after the spasm. Or hitting the rat's head with a small wooden hammer can be fatal. This method seems ruthless.

Acute Massive Blood Loss

The acute massive blood loss of the orbital arteries and/or veins of the mouse can be used to make the mouse die immediately.

Chemical lethality

Inhalation of carbon monoxide, rats and mice can be fatal in an environment with a carbon monoxide concentration of 0.2% to 0.5%. Subcutaneous inhalation of ether and chloroform can be fatal.

We tend to recommend cervical dislocation to kill rats, because it no risk of blood contamination, there is no need to consume anesthetics, and it also avoids the possibility that experimenters may inhale anesthesia and save money. It feels rough to kill with a wooden stick, and the body may be incomplete. The rule of cervical dislocation can avoid the above shortcomings, but many colleagues around me, especially female colleagues, dare not use their hands to catch rat directly for fear of being bitten, some of them have been bitten by rats. So in order to overcome those problems, we have already created a very simple method named Modified cervical dislocation to kill a rat without any other tools or drugs (Table 1).

Methods

Merits

Disadvantages

Cervical Dislocation

No need for anesthetics, economic, guaranteed results

Mass killing of rats, risk of being bitten

Decapitation

Fast and simple

Risk of blood contamination; additional blood further processing

Hitting

Do not touch the rat directly, avoid being bitten

Cruel and inefficient

Acute Massive Blood Loss

Fast and easy

Risk of blood contamination; additional blood further processing

Chemical Lethality

Euthanasia, avoid being bitten

Cost of anesthetics, environmental pollution

Modified Cervical Dislocation

Safe and effective, economic, simple and easy

Mass killing of rats


Table 1: Comparison of rat killing methods.

Critical Technical Notes

Here we introduce the modified cervical dislocation. First, take a box with a smooth bottom, similarly, ensure that the ground is smooth and clean, put the rat in a box, you can also directly use the cage, (Figure 1), and then rotate the box/cage for about 1 minute, at this time, the rat will also follow the box (Movie, S1), you can see that rat is tense during this process, and the skin on the legs and lips is purple (Figure 2). After stopping the rotation, immediately grab the tail of the rat with your right hand (the proximal 1/3 of the tail, do not grab the tip of the tail), wear a thick glove with the left hand to hold the neck, press it on the ground, and then dislocate to death, during this process, generally, the rat will not resist, even if your left hand is not grasped (especially when you feel tired), the rat will not bite you, and then you can easily hold the neck again.



Figure 1: Put the rat in a box, the skin on the legs and lips is normal.
 


Figure 2: The skin on the legs and lips is purple.

What are the points that one needs to be careful of during this process? Here are the suggestions: when rotating the box, don't use too much force to avoid turning over and the rat running out; while rotating the box, observe the state of the rat, not too long.

Conclusion

The method we reported that rats were killed by cervical dislocation after rotating dizzy was safe, effective, environmentally-friendly, practicability and universality are strong. In the future, we hope to design an automatically rotate box, and explore the optimal speed and time to provide a better way to kill rats.

This method of killing rats is currently limited to the cases that the rats do not need to be further collected for experimentation, and it is not suitable for all rat killing situations. The method may cause unnecessary additional effects on some disease models, such as the impact of stress on the metastasis of brain tumors and the impact on the nervous system. We should continue to explore and study the euthanasia strategy for rats, which does not only abide by animal ethics but also should be a safe, simple, effective, and environmentally- friendly way.

Limitations

This method still has some shortcomings. Firstly, cervical dislocation may be the best method, but it may not be practical for killing large numbers of rodents, because this method takes time and effort; Secondly, maybe need a box that can rotate automatically, so the researcher’s energy can be saved; Thirdly, we lack a standard: how long does it take to rotate and what is the proper speed? A more detailed protocol maybe deserves to explore. Fourthly, short-term stress has little effect on mice, but chronic stress may affect both biological behavior and tumor proliferation and metastasis [2]. The experimenter should not use this rotation method many times to stimulate the rats, especially when the stress may affect the experimental results. Lastly, the blood index would change after rotation due to stress, which would affect the related results, this method is highly recommended if there is no need for the next test after the rat euthanasia.

Funding: None.

Disclosures: None

References

1. Daniel Cressey. Best Way to Kill Lab Animals Sought. Nature. 2013;500:130-131.
2. Armaiz-Pena GN, Lutgendorf SK, Cole SW, et al. Neuroendocrine Modulation of Cancer Progression. Brain Behav Immun. 2009;23:10-15.

CORRESPONDENCE & COPYRIGHT

Corresponding Author: Zeyi Cheng, West China Hospital, Sichuan University, China.

Copyright: © 2021 All copyrights are reserved by Zeyi Cheng, published by Coalesce Research Group. This This work is licensed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

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