The Australians tried to get a contraceptive pill for mice to keep the population down because of the infestations to crops but failed miserably and produced a very virulent substance that could very quickly kill everyone in the world!
As you have such a hectic lifestyle Gran I have condensed it for you...............
Mousepox carrier
The researchers, based in Canberra, Australia, were hoping to genetically engineer the mousepox virus to produce a contraceptive vaccine to control mouse populations. Instead they made the virus so virulent that it killed all of the mice in the experiment within nine days of them being injected.
Ofcourse they can easily be sterilised by an ingested contraceptive. The trick is to get to all the mice and ensure they eat it.
If you mean as a solution for a mice/rat problem in the house.... it wouldn't work for long. They will still last for some time and as soon as they die some other ones which have not had access to your 'gift' will move in.