Three, Anoplocephala perfoliata, Anoplocephala magna & Anoplocephalidae mamillana.
Praziquantel is active against all three, I am not certain that pyrantel embonate is , though, even in double dose, I have never used it seriously.
Moxidectin is actually dangerous to big horses as well if you do not get the dosage right, or if there is not enough body fat on the horse, but you just carry on Nathan, you will anyway!!!
I used Moxidectin for two years and never had any problems as my horse are fat and I weighed them before dosing (not because I thought it was dangerous but because it was more economical)
BUT when the alarms started going off I did my research (I was new on the Internet then and it was a boon to me!) and found out how and why the drug works and just why it is so dangerous to Minis, and then heard on a "Big" appy Forum I go on about three BH that had had severe problems with the drug.
It is merely this lazy attitude of only doing them every 13 weeks that gets a lot of horse owners, and I have to admit that, with 30 to do, it was very convenient.
However, since I now know it to be potentially dangerous to ALL equines, I shall not use it again.