Just what the title says… I know it varies area to area but I’m curious as to what people do.
TIA!
At about 4-6 weeks I worm with Pyrantel pomoate. 1 month later, Ivermectin. 8 weeks later, back to PP. Depending on the month, I may do Equimax next, to get both bots and pinworms/tapeworms. I usually do quest after the 6 month mark (could be about 7-8 months), then in the spring, back to pyrantal pamoate, followed by ivermectin 1 month later. By that time they are over a year old, and they slide onto the same rotation as the others in the barn.
I rotate between a double dose by weight of panacur and a double dose by weight of strongid every four weeks through one year old.
I start with a double dose of fenbendazole - want to get a jump on the ascarids.
Then ivermectin 4 weeks later.
4 weeks later, another dd of fen. 4 weeks later, Equimax
I alternate between a dd of fen (or a 1.5x of oxibendazole) for ascarids, and ivermectin for strongyles. Each of those chemicals has too high a resistance issue to the other parasites (ie ivermectin/ascarids, and for SURE fenbendazole and pyrantel pamoate and strongyles) for me to trust there won’t be a problem. I KNOW these chemicals take care of these worms.
After the freeze - Equimax; in the Spring, Equimax again, both when it comes time for that rotation.
Ok, I will be radically different here. With wormer resistance I use a minimal method rather than routine worming. I usually worm once around 3 months and then again at 6 months right before weaning. I have started raising my goats and horses this way and have never had a problem. I use a pasture rotation program (goats and horses) that seems very effective. It makes a lot of sense to do fecals on your animals to help manage parasites rather than routine deworming. This is the trend in goats due to extreme resistance to dewormers. I believe that there have been some articles in the last couple of years regarding this. Having adequate pasture size/rotation and some common sense in feeding are important.
I deworm minimally for adults, but most adults have an immune system that can take care of most things most of the time.
Foals don’t have that, don’t have it for a while, and ascarids especially can cause a great deal of damage in a short period of time.
I’ve read too many case studies of foals with pneumonia that was strongly suspected to be a result of ascarids having reached the lungs because they weren’t properly dewormed early enough.
I guess you are right. I generally have a low horse load on my land and good rotation and cross grazing so I have gotten away with it. My program seems very effective for my horses and goats though.
Here is a good article: http://www.vet.k-state.edu/depts/vmth/equine/pdf/Deworming_Recommendations.pdf
My only issue with deworming every other month is still the ascarids.
The “good for” time for fenbendazole is about 4 weeks, maybe 5. We know that kills ascarids (in a double dose).
Ivermectin still kills at least some ascarids, and in many cases, still kills all of them, but the amount and area of resistance is growing by the day, so one really should assume they aren’t all killed.
So if you use the dd of fen on, say, May 1, then if you wait 8 weeks and use ivermectin on July 1, and wait another 8 weeks for the next dd of fen, Sept 1, you’ve gone 3 months (all of June, July, August) of either no or reduced protection against ascarids. That scares the snot out of me.
If you go every 4-ish weeks, you all but eliminate that window of opportunity for the ascarids, and you’re still using ivermectin only ever 8-ish weeks.
Just my thoughts and reasoning behind monthly deworming 
Every month, rotating pyrantel, fenbendazole, and ivermectin. I would never deworm a baby less. The first foal I ever knew was euth’d at ~7 months because of colic caused by an ascarid impaction. Foal had never been dewormed… a completely preventable tragedy. Regular deworming won’t hurt. Failing to deworm can.
