Internal Parasites Lab
INAG 120 – Equine Health Management
November 16, 2011
Performing Fecal Egg ID/Count

Fecal egg counts are useful for:
 Routine monitoring of parasite status
 Identification of infected horses for targeted
treatment
 Investigation of the parasite status of a new
horse
 Investigation of colic and weight loss
Benefits of Fecal Egg ID/Count

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If parasites known, targeted deworming can be
done
 Lowers cost
 Less chemicals used in horse’s body
Horses with heavy parasite burdens can be
treated before they suffer from a parasite
associated disease
Efficacy of worm control programs can be
monitored
Performing Fecal Egg ID/Count

Limitations of test
 Does not detect immature or encysted stages
of strongyle parasites
 Does not discriminate between large and
small strongyles
 Tapeworms often do not appear
 Results not well correlated with total parasite
burden
Types of Tests

Direct Flotation Method
Qualitative
 Shows what kind of eggs are present

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Fecal Egg Count Reduction Test (FECRT)
Also known as McMaster Method
 Quantitative
 Shows how many eggs are present in one gram of
feces (EPG)

Performing Fecal Count Tests

Supplies Needed
 Fresh feces
 Fecal flotation solution
 Stirrer
 Cheese cloth
 Transfer pipette to syringe
 Fecal egg count kit
 100X microscope
Performing Fecal Count Test
Step by Step Procedure

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Obtain fresh sample of feces, free of shavings
or other debris
Add flotation solution to line A of vial
provided by the kit
Add subsample of fresh feces to bring volume
up to Line B of vial
Using stirrer, stir/mix thoroughly for 20-30
seconds
Performing Fecal Count Test

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Filter solution through a cheese cloth into a
new vial to remove large fecal particles
Immediately draw up sample from vial into
syringe or transfer pipette
Place transfer pipette tip at the edge of the
slide and discharge sufficient sample between
the upper and lower slides to fill the chamber.
Repeat steps to fill the second chamber
Performing Fecal Count Tests

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Place slide on microscope stage
View slide under 100x magnification
Focus on the slide’s grid lines. The eggs will
have floated to the top of the chamber in
effect sticking to the underside of the top slide
Starting from the outside corner, count all eggs
inside each grid utilizing grid lines in an orderly
fashion (from left to right).

Do not count eggs outside of the grid lines
Slide Gridlines
Performing Fecal Test
Performing Fecal Test
Calculation

Record the number of eggs in each of the
grids:

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Grid 1: _________________ eggs
Grid 2: _________________ eggs
Calculate eggs per gram feces (EPG):

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Grid 1 eggs + Grid 2 eggs = ____________ eggs
Sum x 25 = ______________ eggs per gram
Deciphering the Egg Counts
Infestation level
Mild
Moderate
Severe
Fecal Eggs/Gram
< 200
200-500
> 500
Strongyles
Small strongyle eggs (cyathostomes) have a
characteristic strongylid appearance, meaning they are
oval and about 80 by 50 microns, have a thin complete
eggshell, and contain a developing morula.
Ascarids
Round with thick outer layer
Pinworms
This egg has a thicker eggshell with a plug
on one end, is often flattened on one side,
and already contains a developing larva.
Tapeworms
D-shaped
Strongyles
Ascarids
Pinworms
Tapeworms