veterinarian should be involved in de-worming decisions. The first
step is to identify which horses are shedding the most worm eggs.
Each horse has a different level of natural immunity against
intestinal worms, which can’t be determined just by looking at
them. Your veterinarian can run a fecal (manure) test to identify
which animals are the
high-shedders of worm eggs; these 20% of
horses cause 80% of pasture contamination.
be de-wormed frequently, sometimes as often as once a month,
low- and medium-shedders can be de-wormed as rarely as
twice a year. Next, rotating de-wormers must be stopped. Rapid
rotation is the fastest way to create multi-drug resistance as the
worms are exposed to many drugs over a short period of time,
allowing only the “super-worms” to survive. A slow rotation
program, where drugs are changed only once a year, is preferable.
Fecal egg tests should be repeated on a few of the horses 2 weeks
after administering a de-wormer for the first time to ensure the
product is effective against the worms on the farm. All horses on the
farm should be on the same program: it only takes one horse not
being treated appropriately to contaminate a whole pasture.
Reduce reliance on de-worming drugs and control your parasites
naturally. If manure is removed from the pasture every 3-4 days,
the eggs do not have time to hatch into the infectious larvae, and
the need for medications will fall dramatically. Chain harrowing
spreads worm eggs and larvae over the entire surface of a field and
should be avoided unless the weather is very hot and dry. Because
the larvae die in cold weather there is no need to de-worm during
From the above article.
And No, New Bolton is NOT saying the same thing speed racer and Indy and AB are saying.
In fact, New Bolton is saying MOST horses only need wormed once a year.
some, not at all. It depends on the level of shedding. And the vet community is now saying low level shedding may not need treated at all....as a constant low level of worm infestation is beneficial as it makes the horse's immune system kick in to take care of the worms.
Not as one poster said, six doses in three days.
SIX doses in THREE days can indeed be deadly for some horses. That is a serious misuse of wormer.
My comprehension of this issue is in keeping with the current veterinary consensus. Overuse and overdosing of worming meds is causing worm resistance.
It's a fact, even if you three ...and whoever else wants to join your pack.....disagree. It is what it is.
As is this thread, which is NOT about underuse, it's about unusually high doses of wormer given to horses in an incredibly short time.