March 2015
Changing dogma: changes to parasite management in the 2000's to keep your dewormers working
Joan Burke, Ph.D., USDA ARS, Boonville, Arkansas
Jim Morgan, Ph.D., Katahdin Hair Sheep International
Many flocks or herds have issues with dewormers that no longer work. The American Consortium for Small Ruminant Parasite Control (ACSRPC) has reversed the recommendations of many veterinarians and parasitologists that were prevalent prior to 2000 and still advocated by a minority today.
This article is most important for flocks/herds that deworm all sheep/goats two or more times per year. However, the ACSRPC recommends these rules for all flocks/herds so that dewormers will continue to work for all shepherds.
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Do not deworm all sheep or goats before moving to a clean pasture
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Do not deworm all ewes or does prior to breeding
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Do not deworm all ewes or does at lambing/kidding
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Do not deworm all lambs or kids in the mob every few weeks during the summer.
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Do not rotate dewormers on a yearly basis or between each usage.
HEY! WAIT! HOLD IT!
Yes, these rules are the opposite of what we were taught prior to 2000. The dogma from the 1960s to 2000 was to eliminate all worms in the animals frequently. The current recommendations are to “deworm the individuals that need it”. These changes are made so that shepherds can remain in business in five to twenty years without large numbers of dead sheep or goats, or losses in weight gain.
To follow the first four “Do not deworm” statements, a shepherd needs a parasite management program that prevents a large buildup of worms and/or the ability to selectively deworm sheep and goats that need treatment. Selectively deworming sheep or goats is most easily accomplished using the FAMACHA© technique. FAMACHA© is a technique in which shepherds assess the level of anemia by examining the mucosa (red to cream color) in the lower eye lid. When a shepherd takes the course, they receive a card that will be the guide to determine the level of anemia. FAMACHA© only works when animals are infected with the barber pole worm (Haemonchus contortus) that causes anemia, but not for other worms.
A better option is to use the Five Point Check® (which includes the FAMACHA© technique) to evaluate deworming needs. The same South African researchers who developed the FAMACHA© system have developed the Five Point Check® for targeted selective treatment of internal parasites in small ruminants. The Five Point Check® expands the utility of the FAMACHA© system by incorporating other checks to encompass the symptoms and deworming need for other internal parasites of economic significance.
In addition to the eye (FAMACHA©), the back (body condition), the rear end (amount of soiling or indication of diarrhea),
the jaw area (bottle jaw or edema), and the nose (nasal discharge) are examined. See Table and diagram below. For more detail, see http://www.slideshare.net/schoenian/the-five-point-check.
If all your animals need deworming then do it, but change your management and nutrition so that you don’t need to deworm all sheep or goats at the same time. If you must deworm all at once and want to move to a clean pasture, wait a week after treatment before moving.
HEY! WAIT! HOLD IT!
You are talking about lots of extra work.
Yes, it is extra work. But it needs to be done. Use the Five Point Check®, or at minimum, FAMACHA©, to determine which sheep or goats need deworming at breeding, lambing/kidding and during the early growth phase of lambs/kids. It will save you dewormer, which is money.
The final “Do not.” Do not rotate dewormers. Using several different dewormers a year results in the worms in a sheep operation acquiring more and more resistance to all classes of dewormers faster (if it has not already occurred). Population geneticists predict that it is better to use a class of dewormer until it no longer works, and then rotate to a new dewormer. This will keep dewormers in your management tool box for a longer time. If and when we do get a new dewormer, use it as your last resort and never use it to treat all animals in the flock at once.
Find the schedules of FAMACHA© trainings and “Smart Drenching” presentations in your area. If you don’t see one, ask your extension agent or small ruminant professional to schedule a training.
Diagram from Wild and Woolly Fall 2013 issue: (visit http://www.sheepandgoat.com/news/Fall2013.html)
This article first appeared in the Winter 2013 (Volume 25) issue of the Katahdin Hairald; it has been edited for the ACSRPC web site.