For what it's worth ...

The American Veterinary Medical Association approves of CO2 (or similar anesthesia) for euthanizing rodents.

"Wacking" is not approved and generally believe to be cruel/inhumane. If CO2 or anesthetics are not available, cervical dislocation by someone trained in the practice is considered acceptable.

A couple of helpful links ...

2000 Report of the AVMA Panel on Euthanasia - http://www.researchtraining.org/refe...0%20Report.pdf

GUIDELINES FOR USE OF CERVICAL DISLOCATION FOR RODENT EUTHANASIA - http://labanimals.stanford.edu/Guidelines/Cerv_Dis.html

-adam