I have poured gallons of medication into their collective ear canals but the problem persists. The medications my vet prescribes call for treating the cats' ears twice a day for two weeks. In group situations I think that the best treatment for ear mites in cats is almost certainly ivermectin. I have seen several recommended treatment schedules but we usually use it once a month in all the cats for several months. We have used it topically by putting a few drops in the ears and injectably, with pretty much equal success.
Clients obviously do better most of the time when it is used as a drop.
Ask your vet about this. Still, in a situation in which approved medications have failed on repeated attempts it is justified to look for alternatives, I think. My question is that I'm babysitting 2 cats that has ear mites. Rabbits have a different ear mite and the rabbit should not be affected. If you are babysitting these cats at the owner's home it is unlikely that the mites would be transferred by you to your pets.