Response latencies in the tail-flick test depend on tail skin temperature.

Tail skin temperatures and tail-flick latencies were simultaneously recorded in male Sprague-Dawley rats exposed to various ambient temperatures (22-30 degrees C). There was a positive correlation between tail skin temperature and ambient temperature and a negative correlation between tail-flick latency and ambient temperature. Importantly, a highly significant negative correlation was present between tail-flick latency and skin temperature, even at constant ambient temperature (22.1 or 23.3 degrees C). Thus, the results of tail-flick testing are highly affected by skin temperature and factors altering the skin temperature must be considered when tail-flick latencies are interpreted in terms of nociception.