Deworming the unknown... Safely.

[Guilherme]

Timing wise, our first vet here in the Valley suggested we deworm just before the first freeze and again just before the last freeze, That would mean two, maybe three runs during the winter. Since we don’t travel much or have much in the way of outside horses here we are at low risk of high infestation or reinfection. Once they are clean they will stay that way for quite a while. If we travel or get more exposure to outside horses we can always add a dose for additional protection.

I would think the further north you go the better this system might work.

G.

[JB]

The general rule, if you live where there are hard freezes, is to deworm in Fall after a good hard freeze. That’s so that botflies will be killed, and assuming you’ve removed bot eggs from the horse, you can effectively kill the bots already ingested and developing, and not have any further exposure until the Spring.

In the Spring, you want to wait until temps are reliably above 45*. That’s the temp at which strongyle eggs will start hatching into infective larva. At that point, they can start being ingested, and moxidectin (preferably, but ivermectin if not possible) will prevent them from developing to egg-shedding adults for 12 (or 8) weeks.

That holds for all horses, with exceptions. It’s the moderate and high shedders which need additional dewormings. The timing of those may depend on factors specific to your location and management.