Donnington Grove Veterinary Group
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Worm egg counts

The faecal worm egg count is a simple, relatively inexpensive procedure that can be used for parasite surveillance and the detection of anthelmintic resistance. The worm egg count (WEC) will identify the individuals who require worming if a targeted approach to parasite control is being used.

If the pretreatment WEC is compared with a post treatment count the method can be used to perform a 'faecal egg count reduction test'. If the count has been reduced by >95% the treatment is deemed as being successful and no drug resistance problems identified.

The laboratory uses the McMaster flotation technique to count the worm eggs. This technique is good for quantifying strongyle eggs but not so good at quantifying tapeworm infestation. It does not account for the presence of migrating large strongyles or the encysted small strongyles. Ideally the WEC is performed on fresh faeces i.e. <12 hours old and if 24 hours old should have been refridgerated. Results are given in eggs per gram (EPG).

A general guide to results:

<200 EPG LOW

200-1000 EPG MEDIUM

>1000 EPG HIGH

These are the number of eggs laid by active adult worms found in a small quantity of dung.

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