For 4 years I've been using Swiss female mice in a model of drug-induced neuropathic pain. I commonly see a latency time of 8-10 seconds to thermal stimuli in control groups and about 4 seconds in drug-induced pain groups.
However in the last 3 months the latency time for all females are between 4-6 seconds. I note the animals are a bit more stressed than usual. Male mice are responding as usual.
These alterations could be a consequence of bioterium workers? The team that worked there was recently changed. Or a change in the animals phenotype?
How can I solve this puzzle?