Ask the Vet – Deworming foals

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DAN: “Could you please discuss
an appropriate deworming schedule for the first two years
of life, including discussion on developing natural
resistance to parasites by not administering dewormer
prior to a certain age?” So first off, is Rachel here? OK, so Rachel, you
know how to get your question answered
because Dr. Gray loves talking about deworming. Perfect. DR LYDIA GRAY: I
think I want to go with the last part of
that question first. Can you read it again? DAN: Yes. So the last part was
discussion on “developing natural resistance to parasites
by not administering dewormer prior to a certain age.” DR LYDIA GRAY: So I don’t
want to put you on the spot or embarrass you but
what the heck, it’s live. That would be a
myth because I went to the source of all things
deworming and parasite control. And it’s the AAEP. They have guidelines
for parasite control. From all ages. They talk about all
chemical classes, all different kinds of worms. They talk about
fecal egg counts. It’s all there, spelled out. It’s like a 92 page document
and I read it for this evening. And I printed out the
page on young horses. But they say that young
horses should have, at a minimum, four treatments
in their first year of life. And the concept of not
showing the young horse a dewormer when they’re young to
teach their immune system is– the opposite is true. So you want to–
the young horses would be considered
high shedders. So the most damaging
to your facility. And you need to deworm them
like they’re a high shedder. So I’m going to read this part
to make sure I get it right. “The first deworming should
be carried out about two to three months of age.” And that’s with
the benzimidazole. because the worm of interest
with the young horse is the roundworm,
or the ascarid. And your ivermectin and
moxidectins, the roundworms have now become resistant. So we have to use
something else. And so that’s the benzimidazole. The next deworming,
the second one, is recommended just
before weaning. And the assumption is that
happens in the four to six months age range. The third and fourth dewormings
are at 9 months and 12 months. So about every three
months you deworm your baby through their
first year of life. Now they want the first fecal
egg count at weaning also because what’s important is– the worm of concern is the
roundworm or the ascarid. As they age, the worm of
concern becomes the strongyle, specifically this
small strongyle. You start doing fecal egg counts
in that first year of life to know when to stop
using benzimidazoles and start using
ivermectins and moxidectins for the small strongyle because
you can see in the fecals the eggs. So early on, the fecals will
have roundworm eggs, primarily. And as the young horse ages,
the worm eggs in the fecal will turn to strongyle eggs. And when that happens, you can
throw out your benzimidazoles, give them away for
Christmas presents because they’re useless
in the young horse, right? DAN: You’ll be so popular. DR LYDIA GRAY:
You’ll be so popular. And then you start using your
ivermectins and moxidectins. But it’s really important
to deworm the young horse at least four times
because they are contaminating your facility. They’re filling it up with
eggs and they’re making every other young horse– they’re infecting all the other
horses, young and old alike. DAN: So the young horse
isn’t like building up an immunity or something
by not giving a dewormer? DR LYDIA GRAY: Correct. Yeah. Can you say that again? That was actually
really well said so– I know! Here you go. Can you say it again? DAN: Hopefully. No. So a young horse is not
going to build up an immunity by not having a dewormer? DR LYDIA GRAY: Correct. DAN: OK. DR LYDIA GRAY: Yeah. Yeah. Did we say that right? OK. OK, so yeah, so that’s
deworming the young horse. Their first year of life is
really, really important. DAN: So she wants to know
the first two years, though. DR LYDIA GRAY: Well– DAN: Not to be greedy because
that was a great answer. DR LYDIA GRAY: But that’s
what the fecal egg count then tells you because– DAN: And then at that point on– DR LYDIA GRAY: Yeah. At some point, as you keep
doing fecal in a young horse, you figure out when
they change over to primarily
strongyles, which is the worm of concern in the adult
mature horse and not so much round worms. When that happens, you can
start giving the ivermectin and moxidectin. The fecal will also tell you
is that young horse– so now it’s in year two, –a high
shedder or a low shedder. If it’s a high shedder, you
continue to deworm frequently. A low shedder can be dewormed
once or twice a year. DAN: Hope for a low shedder. DR LYDIA GRAY: Low shedder. So yeah, that’s would be the
first year and the second. But it’s all about monitoring. It’s called fecal surveillance. Surveillance and
strategic deworming because of the whole resistance.


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