Improving tail flick analgesic test by a custom made restraining chamber

Tail flick test is a common method for evaluation of acute pain in animal models. However, there seems to be a technical limitation with this test deserving a more subtle consideration. The problem is the use of physical restraining during the test. This in turn exposes the animal to stress which could undesirably affect the obtained results. In the present report, a newly designed restraining chamber is presented to improve the tail flick test regarding the mentioned limitation. Also, the baseline tail flick latency in animals undergone the test using the classic restrainers was compared to that of performed by the designed chamber. Results indicate that the baseline tail flick latency in animals restrained by newly designed box is significantly lower than those restrained by the tube-shaped version and this might be attributed to stress induced analgesia. In conclusion, would like to suggest the use of our custom made box to avoid erroneous measurement of nociceptive threshold in rats.