Assessing worm burdens with diagnostics

float to the surface. The fluid containing the eggs is then collected using a pipette and placed in a counting slide where the eggs are identified and counted under a microscope 3
Which eggs are which?
Large and small redworm eggs look similar so are reported as strongyles. Small redworm are the most common worms to affect horses in the UK so these will constitute the large majority of strongyle eggs. Tapeworm eggs may be seen in FECs but the reliability of the routine methods used is low for this parasite and therefore they are not a definitive test for tapeworm. Ascarids are a common and significant finding in samples from foals and yearlings 34
Understanding the results
The number of worm eggs in the dung sample are measured and reported as eggs per gram epg. Importantly whilst an FEC can provide some indication of horses most at risk of parasitic disease it will not reliably correlate with the absolute number of worms a horse has. Instead it shows how many eggs those worms are producing and this could be different for each horse even if they have the same burden 4  
On this basis the aim of an FEC in adult horses is twofold to treat horses that may be at risk of parasitic disease and to reduce shedding to prevent further contamination of the pasture.
The standard level at which treatment is recommended is usually above 200epg of strongyles depending on the horses age and worming history. If you receive the result 50epg no eggs seen it doesnt guarantee that there were no eggs in the sample as only a very small sample is studied under the microscope. However it is likely to indicate that the horse is not currently shedding large numbers of eggs onto the pasture 4
What to do next
A single faecal worm egg count FEC is only a rough indication of your horses egg shedding at that time and results may vary between consecutive tests. FECs can help you to target your worming treatments by only dosing horses with