The WormScope Method

A faecal egg count (FEC) is a laboratory test that measures how many parasite eggs are present in a horse's manure. It's the simplest, most reliable way to see what's actually happening inside your horse — before you reach for a wormer.

The result is expressed as eggs per gram (EPG). A low count usually means your horse doesn't need worming right now. A high count tells us it's time to act — and helps guide which product will work best.

FEC testing is the foundation of modern equine parasite management, recommended by veterinary parasitologists worldwide.

WormScope uses the Modified McMaster method — the international gold standard for quantitative faecal egg counting in horses. It's the same technique used in university veterinary laboratories and government parasitology programmes.

A precisely measured amount of manure is mixed with a flotation solution. Parasite eggs are lighter than the solution, so they float to the surface. A calibrated McMaster counting chamber captures a known volume of that surface layer, which is examined under a microscope.

Because both the sample weight and the chamber volume are fixed, every count converts cleanly into eggs per gram — giving you a result that is consistent, repeatable, and directly comparable between tests.

Blanket worming every horse on the same schedule is no longer best practice. It drives anthelmintic resistance — parasites evolving to survive the drugs we rely on — and it means many horses are treated when they don't need to be.

Research consistently shows that roughly 20% of horses carry 80% of the parasite burden. FEC testing identifies which horses are the high shedders in your herd so treatment can be focused where it's actually needed.

• Fewer unnecessary chemical treatments for your horses
• Slower development of resistance on your property
• Lower cost across the herd over time
• Objective data to guide worming decisions with your vet

1. 1

   Sample received

   Your samples arrive at the WormScope laboratory by post or drop-off. Each is logged against your booking reference and checked for labelling and condition.

2. 2

   Preparation

   A precise sub-sample is weighed from each horse's manure and mixed with a saturated flotation solution to separate eggs from debris.

3. 3

   Modified McMaster count

   The prepared sample is loaded into a calibrated McMaster counting chamber and examined under the microscope by a trained technician. Eggs are identified, counted, and — where relevant — categorised by parasite type.

4. 4

   Quality control

   Every count is reviewed against internal controls before it's released. Unusual or high-burden results are re-checked.

5. 5

   Reporting

   Your results are written up into a plain-English report and emailed to you, usually within a few working days of the sample arriving at the lab.

• A per-horse egg count in eggs per gram (EPG)
• Identification of parasite types where visible (strongyles, ascarids, tapeworm indicators and more)
• A clear low / moderate / high shedder classification
• Plain-English interpretation of what the result means
• Practical guidance on whether treatment is indicated and when to re-test
• A permanent PDF record you can share with your vet