Basically, a thermal stimulus is applied on the tail; when the animal feels discomfort, it reacts by a sudden tail movement. The tail flick reaction time is then measured and used as an index of animal pain sensitivity.
The difference of this test respect to the hot plate test is that the test can be repeated several times on the same animal (with the condition to respect a minimum resting time between each evaluation – around 5 min), before and after drug administration for instance.
In this test, reliable data are only obtained whether the animals are quiet and immobile during the measurement. In this context, the experimenter commonly place in a holder, so a period of habituation is needed for minimizing the animal stress during the measurement. Experienced experimenter can perform the test without any holder/restrainer.
This test has proved particularly sensitive for studying the analgesic properties of pharmacological substances. It can also be used to evaluate basal thermal pain sensitivity or to study putative genetic differences among animals without drug (‘naïve’).