flush in toilet...
did mercy killing on my mices..i left all my mices (20) at my ex's place while i was finishing my move out.left them there for 2-2 1/2 weeks...
she never fed them,never gae them water and left them on the balcony all that time...most were canibalized only 6-7 were left.barely strong enough to walk...
well i took them in the wood and loaded my .177 rifle...might been overkill but i loved them =( no suffering
then i burried them all in separated holes and put a piece of wood over so nothing dig it out...you probably think i'm crazy now