yes, the people who still do the three month rotational worming switch between ivermectin and pyrantel usually.
There is a new and improved worming routine currently catching on in the horse world, though.
This regimen involves having your horse tested with a FEC test to see IF they have worms at all.....rather than just assuming they do and worming every three months.
We had our two tested in June and the tests came back negative for worms....apparently they were totally worm free. We owe this to them being the only two horses on the property and the fact we clean their field of poop every single day......
we were told by our vet that no further worming was needed until fall, when we have to worm them with a tapeworm wormer....we use Zimecterin Gold.....ivermectin or pyrantel alone will NOT kill tapeworms. And depending on where you live, tapeworms can be a big problem. You need to ask your vet if tapeworms are a problem in your area.
So we worm them in the fall and she said no further worming until spring when we have to worm them for tapeworms again.
She tests their poop for worms once a year....as long as they are worm free....we only have to worm them twice a year with a wormer that contains praziquantel (which kills tapeworms) she says.