Farm Ireland

Sunday 18 February 2018

Tests crucial to keeping control of parasite threat

What tests can I use to identify parasites?

Monitoring of your horse's worm burden should be an integral part of your worm control plan.

There are two types of test readily available to horse owners to determine the worm burden in any horse – faecal worm egg counts (FWEC) and tapeworm antibody tests (TAT).

Faecal Worm Egg Count (FWEC)

Faecal worm egg counts give you an indication of adult parasites in your horse by measuring the number of worm eggs in a dung sample.

The test is readily available through your vet by supplying a fresh dung sample that can be analysed in a laboratory.

This test can detect the presence of egg-laying adult stages of small and large redworm, as well as large roundworm. FWECs are normally reported as eggs per gram (epg).

However the test will not measure your horse's total parasite burden as it cannot detect tapeworm or the presence of larval stages such as encysted small redworm larvae.

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Tapeworm Antibody Test (TAT)

The tapeworm antibody test is used to measure tapeworm exposure, as horses with recent significant tapeworm burdens have raised antibody levels.

Measured using a blood sample, the test does not indicate the actual number of tapeworms present, and cannot distinguish between non-infected horses and those with low infection.

Why should I use these tests?

The FEWC and TAT tests can be used to indicate the level of adult parasite burden in your horse and to help you target your worming treatments by only dosing horses with a significant worm burden (more than 200 eggs per gram).

The tests can also help you to check that your worming programme is working. You can take a test before and after treatment. A failure to completely reduce the worm burden in your horse may indicate resistance to the type of wormer you used.

When should I test?

During spring and summer, a FWEC can be used to tailor dosing for your horse. If your horse's worm burden is suitably low, he/she may not require dosing at that time.

However a FWEC should be conducted at least once every year during the grazing season as a way of checking that your worm control programme is working effectively.

New horses should be quarantined and a FWEC used to test parasite status of the new horse.

Don't forget ... there are some important things to remember about FWEC's:

nA FWEC won't detect encysted redworm, which is the most potentially harmful stage of the redworm parasite.

Horses can have burdens in the order of several million encysted larvae, yet show a negative or low (less than 100 eggs per gram) FWEC.

nPinworms are not reliably detected in standard FWECs because they don't consistently lay eggs as part of their life cycle.

nBots and tapeworm are not identified in FWECs either.

Irish Independent