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ABOUT H-LAB
This
section of the newsletter will have introductions to the people at H-Lab, explanations of
what we do behind the scenes, and highlights about actual customers and their worm
control strategies.
This Month:
Counting The Eggs Before They're Hatched
The
McMasters Technique is a method of counting the eggs in fecal samples; a small amount of manure is placed in a concentrate solution and stirred, shaking loose the eggs
from the manure. The solution and eggs are then placed in a special slide,
called a McMasters slide, in order to count (under the microscope) the unhatched eggs that float to
the surface. Here's how the process works in our lab....
1) Every day
in the mail delivery we receive envelopes with new samples. The envelopes are
refrigerated in the lab in order to maintain freshness, until the samples can
be counted later that evening. Each horse's sample is handled individually for
accurate results and recordkeeping.
2) We make up
a batch of sucrose concentrate solution ahead of time, using simply sugar and
water that's heated until the water fully absorbs the sugar. Other solutions
sometimes used elsewhere include a saturated zinc sulfate or sodium nitrate
solution, but we've found sucrose is safe and works just as effectively. - With
the traditional McMasters Technique, a portion of the stool sample is then weighed before
adding it to the solution; however, since we've found manure can weigh more or
less depending on if it's wetter or drier, we use a 'modified McMasters
Technique' that's based on volume, for a more consistent outcome. We've also
sent control samples to other labs, such as the University of Illinois and East
Tennessee Clinical Research, and found our methods to be consistent with their
findings.
3) Using a set
of special tubes set up in a holding rack, we put 28 ccs of the sucrose
concentrate solution into each tube; adding 2 ccs from a manure sample brings
the level up to 30 ccs. The contents are then stirred, shaking loose the eggs
from the manure and causing them to float in the solution.
4) Drawing off
in a syringe a small amount of the fluid with the eggs still floating in it, we
transfer that solution into the McMasters slide, a small 3-dimensional counting
chamber with a lid. The slide is placed under the microscope, and we then count
the eggs, multiplying by a factor 25 to get the correct count in an 'egg per
gram' (EPG) format.
5) Egg counts
are marked on each sample envelope, according to what horse the sample was
from. We then input the data into our lab computer, and generate a 'results'
form in a PDF that we send via email to the owner; we've found this to be a
better overall notification system, since the results arrive 3-4 days sooner
than they would in the mail.
-
If a horse
has a 'negative' count, no further action is needed for three months, and we'll
send you a reminder the next time that horse is due for a test.
- If your horse
has a 'positive' count of greater than 200 EPG, we'll send you a collection kit
along with your results document, so that you can deworm the horse and follow
up with a re-test three weeks after deworming, to determine the effectiveness
of the deworming process.
- Please remember that you can also call us and request a kit anytime you
want to run a test, since some horse owners like to test their horses more frequently.
We've found this great step-by-step McMasters Technique video from Dr. Thomas Nolan at the University of Pennsylvania School of Veterinary Medicine; many thanks to Dr. Nolan for his kind permission to
link to the video here.
Return to the April issue of Worm Control News
Visit the Horsemen's Laboratory Web site
Worm Control News is written and produced by KempEquine.com
Copyright 2010 Horsemen's
Laboratory. Please contact us at hlab@horsemenslab.com for reprint permission.
Linking to Worm Control News is acceptable, and we would appreciate notification of links so we can
acknowledge them in future issues.
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