Apparently de-worming horses is an often discussed, often heated topic around stables.  Some people insist on worming monthly, others insist on daily feed through, while others use a traditional bi-monthly schedule and a few even insist on NOT worming whatsoever unless a problem is discovered.

We have a hybrid opinion on the topic.  Based on where our horses are kept (pasture), the fact that the soil drains well and is sloping (limited moisture problem) and the fact that our horses are not exposed to horses from outside our herd, we tend to worm on a very limited schedule.  Often only a few times a year.

However, I've recently changed my mind a little for two reasons

1. We actually have a ton of visitors in the pastures including turkeys, white tail deer, elk, and potentially even a few predators from time to time including a cougar and some coyotes.  I don't know if there is a possibility of cross contamination from other species, but it would stand to reason that there could be.   In fact this year I had a problem with the dang turkeys pooping on the hay in the barn.  They apparently think it's a nice roosting place!
2. Second, I recently noticed a worm floating in one of our stock tanks.  Where the heck could a worm come from in the middle of winter, if not from a horse?  Upon further research, I found there are some varieties of parasites that apparently can be coughed up and then re-ingested causing intestinal infestation.  NOT GOOD!

So I decided this year we probably out to error on the side of caution and run our herd through a rotation, bi-monthly on the major anthelminics (sp?) and ensure that we have no residual infestation and everyone is safe, healthy and happy in 2011.  Additionally, I want to double ensure that our mares are strong and healthy should we opt to breed them next year.

Now onto the controversial topic, there are a ton of wormer's out there and it seems that someone has had a terrible experience with every brand!  So what I did was create a schedule of a heavier wormer followed by the safest, yet weakest wormer (Ivermetrin) in the following cycle. 

Interested in our schedule?  Here's the plan …

Here's a great link to a free chart from one of the major pharmaceutical firms (barn chart).