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].

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.

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.

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.

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

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).

Table 1: Comparison of rat killing methods.

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.

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

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.

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.