From Ken Pease
You report on an attempt to show that mice are less stressed by the sweat of female handlers than that exuded by male ones (3 May, p 14). Pain-inducing injections were given to anaesthetised mice and rats, and “when the animals awoke, the team recorded their facial grimaces, a measure of pain intensity”. Pain intensity was thus used as a proxy for stress.
The researchers could have measured stress using pain-free and more externally valid measures such as observing the exploratory behaviour of the mice in open-field environments.
The infliction of pain in the study described was gratuitous and indefensible.
Stockport, Greater Manchester, UK
