The thinking about deworming has changed so much in the 12 years that I have owned donkeys.
When I got my first donk in May of 2002, I was given advice by "reputable" donkey owners to
"give 1/4 tube of Eqvalan (Ivermectin) paste four times a year." No mention of body weight just that "minis get 1/4 tube."
Another very credible internet source was adamant about rotating dewormers and using a product every 60 days in order to interrupt the cycle of egg laying. And to deworm every animal in the herd at the same time. Made sense! Sort of ... except that I just hated the thought of feeding chemicals to my animals that often.
So I tried a variety of herbal products, again from credible suppliers who were (are still probably) adamant that these products (expensive too) work. The one thing I couldn't bring myself to try though was feeding diatomaceous earth. I know there are folks who praise it but to me, it's like feeding ground glass ... right or wrong ( and I'm not sayin' I'm right in this!)
Anyway, now I have a binocular microscope, a jug of sodium nitrate and a set of McMaster slides. I do my own floats to check for internal parasites and I deworm when the count is higher than 200 eggs per gram. I attended a 2-day clinic to learn how to do this, have read oodles about equine parasites and have gone to several talks given by vets and parasitologists.
What's amazing is how infrequently the donkeys actually need treating (if you keep your paddocks clean) and also how unique each animal is. I started checking them in late Fall since deworming after the first frost is a good time, if they need it. No one did!
When I get a low count of strongyle eggs (they are easy to spot!) I check again often, as perhaps they didn't happen to be shedding at the time I gathered a sample. So I don't assume that the donkey has little or no parasites - I will check every week or two. It's not hard to do and doesn't take very long.
So this past Fall Siog needed to be dewormed first, a month later Heather did too but not Rose or Dorrie. I keep a journal of everything. I checked Rose yesterday and again today but only counted 2 and then 3 strongyles (I'll deworm when I count 8 or more.) I'll keep checking Rose and Dorica frequently and will start rechecking Siog and Heather about 8 weeks after the dates they were dewormed.
My biggest challenge is dealing with encysted strongyles. They're the ones that are not in the larval stage and therefore don't show up in a float. It's a good idea to treat for them once per year but I'm leary of using the drugs on the minis. Especially living, as we do, on an island where veterinary help is hard
to come by in an emergency. My plan for treating them is to use Ivermectin in May and then again 3 weeks later - hopefully this will kill of the eggs in the larval stage, inviting the encysted ones to develop and then I'll hit them again. That's my current thinking for now. If anyone has a better idea I'm all ears!