Why would she put garlic oil on them? Cooking rats tonight?

Ivermectin PASTE needs to be used, it's only 1.87% for the whole tube that treats a 1000lb horse. They each need a grain of rice sized dose every day for 2-3 weeks. You can use that or Frontline SPRAY(not the concentrate drops) or Revolution for Kittens(they all need weighed so a specific dosage can be given, but it treats for 30+ days).

Tell her to get the paste or the Frontline spray and don't use the injectable stuff made for cattle/goats. Too high of a dose and tastes freaking awful.

What kind of bedding is she keeping them on? Carefresh is notorious for having mites in it. I get aspen and have never had problems. She may want to freeze the bedding before using it. Did she bring a new rat in that wasn't quarantined?