Pithing

Pithing /pɪθɪŋ/ is a technique used to immobilize or kill an animal by inserting a needle or metal rod into its brain.

It is regarded as a humane means of immobilizing small animals being observed in experiments, and while once common in commercial slaughtering is no longer practiced in some developed countries on animals intended for the human food supply due to the risks of embedded metal fragments and general spread of disease.