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Most horse owners devote considerable
amounts of time and money to controlling intestinal worms. In spite
of this, vets regularly have to treat horses with colic, weight loss
or diarrhoea caused by worms! The fact is that the worms are very
clever at evading our attempts to control them. This article
highlights some of the pitfalls of worm control and suggests some
solutions to the problems.
Why do we need to control
worms in horses?
Because the consequence of not doing so might mean severe disease
for your horse. Each parasitic worm of the horse causes a different
type of problem. Tapeworms can cause colic, small redworms can cause
diarrhoea or weight-loss. What is important to remember is that low
levels of infection do not cause problems. It is horses with heavy
worm burdens that are most likely to suffer from disease.
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Problems
with worm control |
The worming drugs currently available for use in horses are extremely
effective. However, horse owners should realise that individual drugs only
treat certain worms and that some drugs only treat some of the life-cycle
stages of certain worms. A further complicating factor is that some worms
have developed resistance to certain worming drugs. The more frequently
worms are exposed to the drug, the greater the chance of resistance
developing. The bottom line: It is not as simple as giving a dose of
wormer and all the worms are killed!
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Not all horses are equal! Some horses are predisposed to worm
infection and are likely to become repeatedly infected with heavy worm
burdens. Many horses however, are relatively resistant to developing
heavy burdens. With such a variation in individual susceptibility it
makes no sense to treat all horses the same.
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Most horse owners have struggled with the question of which worming
regime is best for their horse. Because every horse is different, and
because the conditions under which every horse is kept are different,
there is no single worming regimen that suits every horse. Your vet is
the person best placed to advise on your particular situation.
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Environmental issues are never far from the news headlines. Did you
realise that some worming drugs have a marked impact on the environment?
Residual drug activity is present in droppings when they fall onto
pasture. This will lead to the death of insects and earthworms that
usually break up the pile of droppings. This does not mean that worming
drugs should not be used. It does mean that they should be used
sparingly and only when necessary.
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Methods
of worm control |
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Pasture hygiene
Scientific studies have demonstrated the effectiveness of
regular removal of droppings from horse pasture. If this is done
twice a week, there is minimal transmission of worms between
horses. Other management techniques that can be used are
rotation of pasture and grazing sheep or cattle on the same
pasture. These species will eat the eggs of the horse worms
without becoming infected, thereby acting as "biological
vacuum cleaners!
Targeted dosing with worming drugs
By using diagnostic tests, heavily infected horses can be
identified and treated. Non-infected horses do not need treating
thus saving money on expensive drugs, reducing the tendency for
resistance to develop and leading to less impact on the
environment. Periodic diagnostic testing is essential for this
method of control. Not only does this allow targeting of worming
drugs it allows horse owners to check that their worm control
programme really is working.
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Interval treatment with worming drugs
This technique involves the repeated use of worming drugs at
specified intervals. At each treatment, more than 90% of the worms
are killed (depending upon the drug used) and the period between
treatments is defined by the speed at which the horse develops an
adult population of worms in its intestine once again. This regime
inevitably involves the treatment of many horses that have only low
levels of infection. However, under certain circumstances, it is the
only safe approach to worm control.
Diagnostic tests
Until recently, horse owners have been happy to assume that all
their horses are infected with worms and to use interval dosing with
worming drugs. There is an increasing awareness that diagnostic
tests, interpreted by veterinary surgeons, can help identify heavily
infected horses and help to target treatment.
- Do you want to spend less on worming drugs?
- Are you interested in a "greener" approach to worm
control?
- Are you worried about resistance to worming drugs?
If you answer "yes" to any of these questions then a
targeted worming regime may be for you!
A simple worm egg count on a sample of droppings gives an
indication of the number of adult redworms a horse is carrying. It
will also reveal large roundworm infection. Tapeworm infection has
traditionally been more difficult to diagnose. Research work at
Liverpool University Veterinary School has lead to the recent
development of a blood test for tapeworm infection. Both of these
tests are now available to veterinary surgeons through "Diagnosteq,"
a specialist parasite diagnostic service run by the University of
Liverpool.
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Benefits
of testing for worms |
By targeting treatment with worming drugs at only those horses with
significant levels of infection, horses and their owners can benefit in a
number of ways:
- Reduced expenditure on worming drugs.
- Reduced pressure on the worms to develop
drug resistance.
- Reduced environmental impact due to
unnecessary use of wormers.
These benefits arise at the same time as
owners knowing that worms are controlled in their horses. They know
this because they have test results to prove it!
This approach to worm control is not just
scientific theory. We know that it works. An increasing number of horse
owners and vets are using diagnostic tests to target worming drugs. Most
owners who try this method find it to be cost effective and are pleased with
the "peace of mind" that it brings them. Diagnostic tests have
also been used to help reduce the incidence of colic in yards with worm
problems.
For more detailed information, visit our
website:
www.diagnosteq.co.uk or
talk to your vet about getting your horses tested.
diagnost@liverpool.ac.uk
Visit our website at
www.diagnosteq.co.uk
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Article kindly supplied by:-
Diagnosteq, "Solutions to worm control", Equine Division, Leahurst,
Neston,
Wirral
CH64 7TE
Tel/Fax: 0151 794 6184
email: diagnost@liverpool.ac.uk
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