Any medication you use on your rabbits impacts them and you somehow, so never use anything lightly. Research it fully before you try it.
Ivermectin is a pesticide. It is used widely for many different animals, and is not generally prescribed for rabbits as it has not been tested on rabbits, as far as I understand. Using Ivermectin is "extra label" usage and each person must decide how they feel about it. That said, I have been using it for over 10 years with no ill effects that I have been able to see. There is some concern about pesticide residue in the systems of breeding rabbits, as there SHOULD BE!, so I double the safe withdrawal time. It is 30 days after injection for consumption of livestock, so I leave 60 days for my breeding rabbit stock to recover. I used to inject it, but it became a hassle and I tried administering it orally after a number of other rabbit breeders had good luck that way. I am pleased with the results, and continue to use it orally.
Fur mites are my own personal enemy here at Countrywool. I don't often read too much about the PITA they are from other breeders. It's almost like they are an unspoken horror. For me they are a part of having angoras and I do battle on a regular basis. I cannot envision a rabbitry that won't have them crop up once in a while.
Fur mites are teeny tiny critters that one never actually sees. One sees the results of their presence in the itchy behavior of the rabbits, and in waxy dandruff residue on the skin. They don't bother the animal in any harmful way but they are a NIGHTMARE for fiber producers! For when bunny scratches and itches herself repeatedly, and there is more than 3" of fur.....there goes the coat! It becomes a webbed, matted mess that is tough to clip off cleanly, harder to process easily, and must be treated to kill the mites before it is used. As I like to plan for a LONG 4-5" coat before clipping, controlling the fur mite population about 2 months AFTER one clipping and before the next is the crucial time.
Dosage: I use 1% Bovine IVOMEC. You may use any ivermectin form if you can measure it carefully and make adjustments for the weight of the rabbit. For my hefty 10 pound rabbits, using a needle and syringe, I measure out .33cc. Put the rabbit on her back, holding her ears down under your arm, and slide the syringe into the corner of her mouth. It is bitter tasting, but they don't mind at all. I generally offer a handful of hay once they are back in their cage.
Stubborn fur mite cases need a repeated dose 2 weeks after the first one, and the best way to eradicate them completely is to clip the rabbit to the skin right after you dose her/him. The ivermectin is exuded by the skin and that is what kills the mite. If the mite travels to the ends of the hair of the rabbit, it can successfully remain alive until the ivermectin loses potency in the rabbit.
Fumigating the barn with SEVIN, sterilizing the cages and using a blow torch to remove all hair from all wire and wood that bunny comes into contact with, are other things that need to be done if you can't get rid of/control them.
I have accepted a "controlled population" approach to them. I do sterilize the barn once a year and the mite issue is non existent for a while, but they generally come back in time. I treat all angora with flea powder containing carbaryl right after it is clipped, and remove what I can as I process the fiber into roving for spinning. In fact, flea powder that contains carbaryl is a great way to deal with fur mites ON the rabbit if you do not use ivermectin (which is expensive to get yourself set up with to use). For single/double bunny owners, the flea powder is generally enough if you use it every week until all signs are gone. I keep HAPPY JACK FLEA POWDER in stock here at COUNTRYWOOL.