Down Farm, Lamerton, Tavistock, Devon, PL19 8QA, UK
Tel: (01822) 613838, Fax:(01822) 616122
FACT SHEET No.5
TAPEWORMS: SHOULD I WORRY?
Now that an effective treatment for tapeworms is available, clients often ask
whether they should be treating their horses. Let us review the evidence:
How common are they? Several UK surveys have shown that tapeworm
infection is common and about two-thirds of horses are infected. Infection
is present on most equine premises. Tapeworm eggs are shed in faeces and are
ingested by tiny forage mites present in the herbage mat. They develop in
the mite for four months, and the life cycle is completed by horses inadvertently
ingesting infected mites while grazing. Spread therefore readily occurs between
grazing horses.
Do they cause any harm? A study was conducted recently at a
horse abattoir near Bristol in which the digestive tracts of
20 randomly selected horses were examined for the presence of tapeworms.
Tapeworms in the caecum of 16 of them, either just a few worms (1-20 worms
in nine horses) or large numbers (more than 100 worms in seven horses).
In every case
where tapeworms were present there was scarring of the intestinal tract.
In some cases the pathological changes were severe.
What are the ill-effects? Tapeworms attach to the wall of the
caecum and cluster principally around the opening between the ileum and
the
caecum, the ileo-caecal valve. Scarring of this valve limits the extent to
which it can open to allow ingested food to pass through. In severe infections
the average size of the opening of this valve in one study was reduced from
4cm in normal horses to 1cm. Failure of this opening to permit normal flow
of partially digested food material will cause pain (colic), and potentially
may lead to more serious problems such
has intussusception (telescoping of one portion of the bowel into another)
or complete obstruction and consequent overfilling of the ileum (ileal impaction)
Do tapeworms cause colic? Scientists at Liverpool University recently
asked vets to collect a blood sample from every case of colic they treated
and at the same time to collect a second sample from a normal horse similar
age, breed and sex on the same premises. Using a blood test developed for
the diagnosis of tapeworm infections, the scientists found that the less severe
colic cases were eight times more likely to be infected with tapeworms than
normal horses. In more severe cases of colic caused by impaction of the ileum,
affected horses were 26 times more likely to harbour tapeworms.
Is there a case for routine treatment for tapeworms? The available
evidence strongly suggests that the answer is YES. It presents an opportunity
for horse owners to make a positive effort to reduce the risks of colic occurring.
Tapeworm treatment should be incorporated into to your annual worming programme.
A minimum of a single annual treatment, at any time of the year is necessary
although two treatments, in the spring and autumn, are preferred. The following
drugs are available:
Pyrantel (Strongid-P or Pyratape) This must be given at double the normal dose used for redworm control
Praziquantel. This is available on its own (Equitape)
or in combination with ivermectin (Eqvalan Duo, Equimax). The combination
product allows redworms
and tapeworms to be treated in a single treatment. Praziquantel is probably
a more effective tapeworm treatment than pyrantel.
DISCLAIMER
This factsheet is intended for use by registered clients of EqWest only. The
advice offered is general advice only. EqWest clients who wish to discuss
the individual circumstances of their horse should contact the Clinic.
To speak to a vet please phone between 8.30 - 9.30 am on weekday mornings.
