I don't, but I'm thinking very seriously of doing regular worm counts for PF (did this in the UK) and worming a couple of times a year for tapeworm and the other feckers that don't show up!! (encysted jobbies
Only (as far as I'm aware) for cattle. However, this same stuff can be administered orally to horses. I've used Ivermectin like this; comes in a big bottle that you suck out with a large needle and syringe. Works out very very cheap.
They inect too low and nick one of the ligaments near to the spine.
Ive seen other things bring a swelling up in that area for a few days(penicillin etc), but the wormer seems to leave its mark for a long time. Even when it goes down completely, they always get a funny little sweat mark there.
When i was breaking in and selling for a stud up in Shropshire, we used to get groups of 4 or 5 in every week (untouched and usually 3 to a stable) and after a few days attempt to worm them. Used to use a big bottle with a 'gun' on the end, and inject it in. It must have been cattle wormer, cant remember the name though, begins with I? That was fun, usually managed to get headcollars on and corner them. I got the flippin injection in my arm one day, luckily didnt pierce my fleece, that would have been nasty
Dont like the injections, real 'cowboy' stuff but obviously cheaper for the stud