Internal Parasites Internal Parasites Lab Lab

INAG 120 – Equine Health ManagementINAG 120 – Equine Health Management

November 16, 2011November 16, 2011

Performing Fecal Egg Performing Fecal Egg ID/Count ID/Count

Fecal egg counts are useful for: Fecal egg counts are useful for: Routine monitoring of parasite Routine monitoring of parasite

status status Identification of infected horses for Identification of infected horses for

targeted treatment targeted treatment Investigation of the parasite status Investigation of the parasite status

of a new horseof a new horse Investigation of colic and weight Investigation of colic and weight

loss loss

Benefits of Fecal Egg Benefits of Fecal Egg ID/CountID/Count

If parasites known, targeted deworming If parasites known, targeted deworming can be donecan be done Lowers costLowers cost Less chemicals used in horse’s bodyLess chemicals used in horse’s body

Horses with heavy parasite burdens can Horses with heavy parasite burdens can be treated before they suffer from a be treated before they suffer from a parasite associated diseaseparasite associated disease

Efficacy of worm control programs can Efficacy of worm control programs can be monitoredbe monitored  

Performing Fecal Egg Performing Fecal Egg ID/CountID/Count

Limitations of testLimitations of test Does not detect immature or Does not detect immature or

encysted stages of strongyle encysted stages of strongyle parasites parasites

Does not discriminate between large Does not discriminate between large and small strongylesand small strongyles

Tapeworms often do not appear Tapeworms often do not appear Results not well correlated with Results not well correlated with

total parasite burdentotal parasite burden

Types of TestsTypes of Tests

Direct Flotation MethodDirect Flotation Method QualitativeQualitative Shows what kind of eggs are presentShows what kind of eggs are present

Fecal Egg Count Reduction Test Fecal Egg Count Reduction Test (FECRT)(FECRT) Also known as McMaster MethodAlso known as McMaster Method QuantitativeQuantitative Shows how many eggs are present in one Shows how many eggs are present in one

gram of feces (EPG)gram of feces (EPG)

Performing Fecal Count Performing Fecal Count TestsTests

SuppliesSupplies NeededNeeded Fresh fecesFresh feces Fecal flotation solutionFecal flotation solution StirrerStirrer Cheese clothCheese cloth Transfer pipette to syringeTransfer pipette to syringe Fecal egg count kitFecal egg count kit 100X microscope100X microscope

Performing Fecal Performing Fecal Count TestCount TestStep by Step ProcedureStep by Step Procedure Obtain fresh sample of feces, free Obtain fresh sample of feces, free

of shavings or other debrisof shavings or other debris Add flotation solution to line A of Add flotation solution to line A of

vial provided by the kitvial provided by the kit Add subsample of fresh feces to Add subsample of fresh feces to

bring volume up to Line B of vialbring volume up to Line B of vial Using stirrer, stir/mix thoroughly Using stirrer, stir/mix thoroughly

for 20-30 secondsfor 20-30 seconds

Performing Fecal Count Performing Fecal Count TestTest

Filter solution through a cheese cloth Filter solution through a cheese cloth into a new vial to remove large fecal into a new vial to remove large fecal particlesparticles

Immediately draw up sample from vial Immediately draw up sample from vial into syringe or transfer pipetteinto syringe or transfer pipette

Place transfer pipette tip at the edge of Place transfer pipette tip at the edge of the slide and discharge sufficient sample the slide and discharge sufficient sample between the upper and lower slides to between the upper and lower slides to fill the chamber. fill the chamber.

Repeat steps to fill the second chamber Repeat steps to fill the second chamber

Performing Fecal Count Performing Fecal Count TestsTests

Place slide on microscope stagePlace slide on microscope stage View slide under 100x magnificationView slide under 100x magnification Focus on the slide’s grid lines. The eggs Focus on the slide’s grid lines. The eggs

will have floated to the top of the will have floated to the top of the chamber in effect sticking to the chamber in effect sticking to the underside of the top slideunderside of the top slide

Starting from the outside corner, count Starting from the outside corner, count all eggs inside each grid utilizing grid all eggs inside each grid utilizing grid lines in an orderly fashion (from left to lines in an orderly fashion (from left to right). right).

Do not count eggs outside of the grid linesDo not count eggs outside of the grid lines

Slide GridlinesSlide Gridlines

Performing Fecal TestPerforming Fecal Test

Performing Fecal TestPerforming Fecal Test

CalculationCalculation

Record the number of eggs in each of Record the number of eggs in each of the grids:the grids:

Grid 1: _________________ eggsGrid 1: _________________ eggs Grid 2: _________________ eggsGrid 2: _________________ eggs

Calculate eggs per gram feces (EPG):Calculate eggs per gram feces (EPG): Grid 1 eggs + Grid 2 eggs = ____________ Grid 1 eggs + Grid 2 eggs = ____________

eggseggs Sum x 25 = ______________ eggs per gramSum x 25 = ______________ eggs per gram

Deciphering the Egg Deciphering the Egg CountsCounts

Infestation Infestation levellevel

Fecal Fecal Eggs/GramEggs/Gram

MildMild < 200< 200

ModerateModerate 200-500200-500

SevereSevere > 500> 500

StrongylesStrongyles

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.

AscaridsAscarids

Round with thick outer layer

PinwormsPinworms

This egg has a thicker eggshell with a plug on one end, is often flattened on one side, and already contains a developing larva.

TapewormsTapeworms

D-shaped

Strongyles

TapewormsPinworms

Ascarids