Equine Parasite Control: The Role of Faecal Egg Counts (FEC)
Date: 1 Aug 2025
In New Zealand's warm, humid climate, parasites pose a year-round threat to horse health. Overuse of dewormers has led to drug resistance, making targeted parasite control more vital than ever. This is where Faecal Egg Counts (FECs) come in.
A FEC is a simple diagnostic tool that measures the number of parasite eggs in a horse’s manure. It helps determine a horse’s parasite burden, identifies high shedders (those shedding large numbers of eggs), and assesses the effectiveness of deworming treatments. Fresh manure samples, refrigerated immediately after collection, provide the most accurate results.
Why FECs Matter By pinpointing which horses need treatment, FECs help prevent overuse of drenches and reduce pasture contamination. Strategic deworming based on FEC results allows for sustainable parasite control, preserving the effectiveness of treatments for the long term.
Common Parasites Detected:
- Small strongyles: Most common and drug-resistant
- Large strongyles: Less common, but can cause serious illness
- Ascarids: Typically affect young horses
- Tapeworms: Not detected via FEC but identified through blood or saliva tests.
Best Times to Test
Conduct FECs in spring and autumn to assess parasite load. Test again two weeks after drenching for high shedders to ensure the treatment worked (Faecal Egg Count Reduction Test).
Smart Deworming Tips
- Always test before treating
- Target horses with egg counts over 500 EPG
- Alternate deworming products annually
- Dose accurately based on weight
- Don’t move horses to clean paddocks immediately post-treatment
- Horses under 18months need to be drenched every 3 months. Contact our team for the latest best practices.
Environmental Management
Regular manure removal, cross-grazing with sheep or cattle, and rotating/resting pastures significantly reduce larvae populations.
Protect your horse by making parasite control a routine part of your care program — prevention starts with good habits!
Dr Alana Mockett BVSc
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