Faecal Worm Egg Count

Faecal Worm Egg Count

Faecal Worm Egg Count
At least 50 g fresh faeces
Faecal worm egg counts can be used in several distinct scenarios and with different
interpretations.

Targeted deworming program – the aim is to reduce pasture contamination with
worm eggs. Therefore, horses producing higher FWECs (usually >250 to 500 epg) are
then dewormed and those producing less pasture contamination are not.
Investigation of weight loss or gastrointestinal disease – the aim is to determine if
the examined horse is parasitized. Even if just 1 worm egg is identified then this
confirms that parasites are present and treatment should be offered if it is
considered that parasitism might be contributing to the clinical concerns.
Herd assessment of efficacy of dewormer drugs

a. Efficacy is usually assessed by the faecal egg count reduction test (FECRT)

which, broadly assesses the average decrease in FWECs in a group of egg-
shedding horses 2 weeks after deworming. Resistance is usually indicated

by values below 90-95% reduction.
b. Egg Reappearance Period (ERP) can also be used as an index of decreased
anthelmintic efficacy (although not strictly resistance). FWECs can be
measured weekly in a group of egg-shedding horses every week after
deworming until significant numbers of eggs are detected.