It's not particularly difficult. The method depends on jurisdiction and what is going to be done with the remains. If you need those for further testing, for example.
Without looking it up, I would guess the go-to method usually would be anesthesia followed by an overdose of narcotics or a special euthanasia agent. It's just that a "Mini pig" of 70kg or more will require higher volumes of all of that compared to to a mouse or even a beagle. Of course, when using pharmaceuticals you can't use the meat.
In the EU it is also very dependent on what kind of medications the pigs received during the testing. Only if all of those have been explicitly allowed for meat production can the meat be used at all. Here in Germany the researchers would include the "what do I do afterwards with them" in the planning. So in some cases, like for experiments on feeding or maybe vaccines (if no infections are attempted) then they may actually plan to bring them into the food chain.
Without looking it up, I would guess the go-to method usually would be anesthesia followed by an overdose of narcotics or a special euthanasia agent. It's just that a "Mini pig" of 70kg or more will require higher volumes of all of that compared to to a mouse or even a beagle. Of course, when using pharmaceuticals you can't use the meat.
In the EU it is also very dependent on what kind of medications the pigs received during the testing. Only if all of those have been explicitly allowed for meat production can the meat be used at all. Here in Germany the researchers would include the "what do I do afterwards with them" in the planning. So in some cases, like for experiments on feeding or maybe vaccines (if no infections are attempted) then they may actually plan to bring them into the food chain.