The other day a friend who is a relatively new horse owner called to ask a few questions about basic equine management. He had questions on things like hoof trimming, feeding, and ground manners. Then he asked, What about worming? I've heard about that. How often do I need to do it?
Ask that question in any group of horse owners, and you're guaranteed to open a can of worms -- if you'll pardon the terrible pun.
I've heard some vets say that if the horses aren't pastured in overcrowded conditions, you only need to worm quarterly. Others swear by a strict adherence to an 8 week schedule, with clockwork-like product rotation. Still others say the daily wormer is the only way to go...
I told my friend that I generally worm every 8 to 10 weeks, though sometimes I may skip a dose in the wintertime.
Hmm...., he said. So you're saying it should be more than just once a year?
I can't fault him too much, however. Many well-meaning owners aren't that knowledgeable about parasite prevention or very well-versed in what different worming products do.
When talking about an equine worming program, the short answer is: have one.
* Rotate the product you use on occasion, to prevent your horse from developing an immunity to the wormer.
* Quarantine all new horses and worm them with something like ivermectin before introducing them into an established herd.
* Avoid overcrowded pasture conditions.
* Develop a regular worming schedule, write it on the calendar, and stick with it.
* Oh -- and don't go a year between doses...