Hi Melinda, Yes be very worried and concerned! They will be using a Rodenticide that will kill a ferret if it is eaten. The Rodenticide always comes in some form of edible material, they can not spray for mice. The material could be in block form, impregnated corn, etc. More important is to ask what the residual time. It can be up to 2 months, in some favorable conditions. The mice may disappear in 3-4 days, but the rodenticide will still be there. If you have any visible openings, you can use the metal circles from an open can of veggies, etc., you can also by heavy duty steel wool and stuff tightly in holes. Please go thru your home at the level of your fuzzies and close every opening. When you think you may have covered them all, your fuzzy will find one. Dooks [Posted in FML issue 2671]