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Worm Control News
November 2012

In This Issue
fecal egg count calendar
Many of our clients have asked for a deworming schedule. We explain that we base the deworming protocol on the fecal egg findings and egg count.
Fecal egg count kit gift
Our kits make great grab bag gifts, stocking stuffers, and gifts for gift exchanges (for people you know who have horses, of course!). Order online, call if you have questions.
encysted strongyle
The most often-asked question is, "How do I know if my horse has encysted strongyles?" There are three ways to find out if your horse has them.
Doc Byrd
Oct. 5: Horses in the Morning radio interview with Dr. Byrd. You can still listen.
Dr. Byrd attended the International Conference on Equine Infectious Diseases October 21-26   


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fecal egg count calendar
Deworming Schedule Based on Fecal Egg Counts

fecal egg count calendar  Many of our clients have asked for a deworming schedule until we explain that we base our deworming recommendation on the fecal egg findings and egg count.

  • The species of worm eggs found
  • The number of eggs counted per gm of feces
  • The life cycle of the worm indicated by the eggs found
  • The sensitivity of the worms to various deworming medications

Eight other factors impact individual situations including:

  • Age of horse
  • How horse is kept (pasture, clean box stall, dry lot, sand pen)
  • When horse was last dewormed
  • Number of horses in pasture together
  • How frequently new horses are brought into pasture
  • Geographic location
  • Climate
  • How horses are fed (on the ground, in feed tubs and mangers)

Fecal Egg Counts Affect Deworming Schedules

Deworming schedules have always been based on strongyle worms. Strongyle eggs are the most commonly found eggs in a fecal egg count.

  • There are over 40 species of strongyles and they are very prolific egg layers.
  • Over 95% of positive samples we see are positive for strongyle eggs.
  • Both classes (large and small) and all species of strongyle eggs appear very similar on the egg counting chamber. The species can only be identified after the eggs hatch and the larvae are differentiated.
  • Through larva identification it has been estimated that over 90% of the eggs found today are from small strongyles.

Because of their predominance, deworming schedules have always been based primarily on the presence of strongyle worms. However, now the recommendation is to deworm individual horses according to whether they are low, medium, or high shedders of strongyle eggs.

  • Low shedders
    0-200 eggs/gm
    Deworm 1-2 times/year
  • Medium shedders
    200-500 eggs/gm
    Deworm 2-3 times/year
  • High shedders
    500 or more eggs/gm
    Deworm 4 times a year

Fecal egg counts should be used to determine a general deworming schedule, however the eight situational factors listed above should also be considered when making individual decisions about developing a worm control program.

Horsemen's Laboratory Stool Sample History

With over 20 years of experience performing more than 20,000 fecal egg counts, Horsemen's Laboratory found that 85% of the samples we received have been negative (no eggs seen on counting chamber) or less than 200 eggs/gm-these horses are considered low shedders.

Clients often ask what we consider extreme counts. It's our opinion that anything over 2000 eggs/gm can be considered extreme-we have received samples with counts over 5000 eggs/gm.

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Christmas_gift
Fecal egg count kit giftLooking for a Unique Christmas Gift?

Why not purchase Horsemen's Laboratory fecal egg count kits for your friends with horses for Christmas. Horsemen's Laboratory gift to you will be one free kit If you order six. For friends who already know and use Horsemen's Lab service, a kit will be a welcome addition to the "keep-your-horse-healthy" arsenal. For someone who may not yet be doing fecal egg counts, it's a good way to get them started on the proper worm-control protocol of testing first, deworming only when necessary. (Proper testing and deworming benefits all horses pastured together.) If your boarding barn has a Christmas, holiday or New Year's party, a kit would be great for a grab bag or gift exchange. Don't forget stocking stuffers, too. Kits will be identified with your name on back of the small plastic bag which horse owners fill out before sending their sample.

If you have questions about giving kits as a gift, you can contact Horsemen's Laboratory:

  • e-mail [email protected]
  • telephone 1-800-544-0599
  • contact form at www.horsemenslab.com
  • post your question on Facebook

Use our app on Facebook, visit Horsemen's Laboratory order page, or call 1-800-544-0599 to order.

This offer is valid until January 15, 2013.

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summer_shipping
encysted strongyle What Exactly Are Encysted Strongyle Larvae and How Did They Get in My Horse?

Horsemen's Laboratory receives several questions a week about encysted strongyles. The most often asked question is, "How do I know if my horse has encysted strongyles?" There are three ways to determine if your horse has encysted strongyles:

  • Have surgery performed and have the lining of the large intestine examined for them.
  • If the horse dies, have a necropsy performed and have the lining of large intestine examined for them.
  • The most rational way to find out is to do a series of fecal egg counts over a year or so. Though not as precise as the first two methods, fecal egg counts will be much less expensive, and invasive.

There are some people who think that fecal egg counts cannot determine the presence of encysted strongyle larvae. It is true that a single fecal egg count cannot determine their presence directly. However, fecal egg counts repeated over time will indicate the likelihood that encysted strongyle larvae are present. Knowing something about the life cycle of small strongyles is critical to understanding why this is so.

We should first understand that every adult strongyle was once an encysted strongyle larva in the lining of the large intestine. Therefore, eggs in the horses stool are indicative of adult strongyles in the intestine that once were encysted larvae. At this point we should review the life cycle of small strongyles.

Strongyle Life Cycle

  1. Eggs are laid in large intestine by adult strongyles.
  2. Eggs are passed in the horse's stool.
  3. Eggs hatch and develop into 3rd stage infective larvae. As the eggs hatch, they go through 3 larval stages in approximately 1 week under ideal conditions of 65-85 degrees F with moisture. The 3rd stage develops a coating that protects them when eaten by a horse. Infective larvae climb the blades of grass and wait for a passing horse to eat them.
  4. The 3rd stage infective larvae are eaten by the horse while grazing and pass into large intestine.
  5. Once eaten by the horse, the larvae burrow into the mucosal lining of the large intestine and become encysted. The larvae can remain in cysts for anywhere from two weeks to more than two years. It is not well understood what causes the larvae to leave the cyst (excyst) and become adult strongyle worms.
  6. Larvae excyst, become adults, and begin laying eggs, which are then seen microscopically in the stool sample.

As the life cycle indicates, every encysted larva began as an egg passed in the stool of a horse and will at some point develop into an egg-laying adult.

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wordbyrd
Dr. John ByrdA Word from Dr. Byrd
Horses in the Morning Radio Interview

Dr. John Byrd was interviewed on Horses in the Morning radio on Friday, October 5th at 9:30 a.m. eastern time. During the light-hearted interview, Dr. Byrd discussed importance and timing of fecal egg counts, deworming, and parasite resistance. If you missed the radio interview, you can still listen. Download the episode or listen to the interview using the default or your preferred player from http://www.blogtalkradio.com/horsesinthemorning/2012/10/05/horses-in-the-morning-for. The interview starts at about 30:00 minutes and goes to about 46:30 or so.

International Conference on Equine Infectious Diseases

Dr. John Byrd also attended the 9th International Conference on Equine Infectious Diseases hosted by the University of Kentucky's Maxwell H. Gluck Equine Research Center in Lexington, Kentucky. The five-day conference from October 21-26, 2012 covered infectious and parasitic diseases of the respiratory, gastrointestinal, reproductive, and nervous systems. The conference was attended by international veterinarians and researchers. During the conference, Dr. Byrd had the opportunity to discuss the latest equine parasitology research with leading researchers. Visit the Conference on Equine Infectious Diseases proceedings web page (PDF) to see details about the presentations.

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