Hi Chiptastic, i dont know if you are aware if the chips live outside they can pick up other unwelcome guests from passing wildlife but frontline for cats and dogs can be used (NOT the spot on type) but spray just dip cotton bud in the liquid shake it so as not to get too much one drop then place bud on back of neck of each chip as prevention is better than cure, worked on mine as had plenty when we rescued them but now no mites/fleas/ticks etc and as i am living in the country you never know what wildlife passes by and what visitors they might leave behind by but i did check with my vet before i used it just incase it was dangerous or if there was a similar prevention for small furries,