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Summer
Worming
by Helen Barnes BSc (Hons) DMM DipM MCIM,
Fort Dodge Animal Health.
The typically warm and moist
conditions of the British summer are ideal conditions
for parasites, with infective larvae on the pasture
at their greatest levels during this time of year.
The ways horses are kept influence
the impact of parasites. Wild horses are free to graze
over very large areas and so avoid eating from pasture
that has been contaminated with potentially infective
droppings, meaning that parasites are less able to infect
horses and thus unable to complete their lifecycles.
For domestic horses; however, grazing is often limited
thereby increasing their exposure to infection; as such
action is required to reduce the number of infective
larvae on the pasture.
This
reduction of pasture contamination is achieved by a
combination of worming and pasture management, with
the most common parasite present on the pasture being
the small redworm. A member of the roundworm parasite
class, the small redworm is found universally wherever
horses are grazed.
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Summer
Worming Treatments:
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· Routine Roundworm
Control: Routinely treat against roundworm.
Dosing intervals based on active ingredient, i.e.
moxidectin every 13 weeks, ivermectin every 8-10
weeks, pyrantel every 4-8 weeks or benzimidazole
every 6-8 weeks. When planning your routine worm
control it is important not to use wormers against
which there is known resistance. With resistance
to benzimidazole1 and pyrantel2 based wormers these
should only be used following guidance from your
vet. |
Summer
Worming Tips:
· Remove
horse droppings from your pasture at least twice weekly
to help reduce the number of worm eggs and larvae on
the pasture.
· If possible
graze horses alongside sheep or cattle, since worms
that affect horses are host specific and therefore any
larvae eaten by sheep or cattle are destroyed.
· Harrowing
is only advisable in dry hot conditions where exposed
worms are killed by the heat. In damp conditions, even
if warm, harrowing simply spreads worm eggs and larvae
over the pasture and so increasing their chance of being
ingested by horses.
1.Fisher
MA et al. Veterinary Record (1992) 130: 315-318.
2. Coles GC et al. Veterinary Record (1999) 145: 408.
For
further information on worming plus a free
worming calendar, call the EQUEST/EQUITAPE literature
hotline on 01489 774232 or
Email:equest-uk@fdah.com
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