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Protecting Sheep and Goats from Internal Parasites

Posted 8/6/2009

Control of internal parasites is normally not a big concern in this region due to the dry climate. However, if you are grazing on irrigated pastures and with the recent wet spring and above normal rainfall experienced in June, sheep and goat producers may want to pay closer attention to internal parasites. Especially, Haemonchus contortus (barber pole worm, stomach worm), may be of primary concern for the majority of sheep and goat producers. This parasite has become more difficult to manage because it was become resistant to deworming medications. A severe infection of barber pole worm causes anemia, bottle jaw, and if not treated, death of infected sheep and goats.

Mature parasites breed inside the host and lay eggs that are shed in the feces. Warm, humid conditions encourage the eggs to hatch. The infective larvae migrate 1 to 3 inches up blades of grass. When a sheep or goat grazes, it may take in parasite larvae along with the pasture grass. Parasite numbers increase over time in warm, wet conditions. Because internal parasites are developing resistance to deworming drugs, it is important to use multiple management practices for control.

Manage pasture carefully by: Keeping forage height greater than 3 inches, Providing areas to browse, such as, brush, shrubs, small trees, Maintaining low stocking rate, Grazing sheep and goats with cattle, or in rotation with cattle or horses, Avoiding wet patches in pasture, such as from a leaky water trough, Reducing Deworming - This will slow drug resistance and save money, Treat only animals that are anemic, which is a sign of parasitism.

You may utilize a FAMACHA© chart for classifying animals infected with Haemonchus contortus based on levels of anemia.

Recently, a clinical on-farm system, called FAMACHA©, was developed in South Africa for classifying animals into categories based upon level of anemia. Since anemia is the primary pathologic effect from infection with H. contortus, this system can be an effective tool for identifying those animals that require treatment (but only for H. contortus). To use FAMACHA©, the color of ocular mucus membranes are observed and compared to a laminated card which has colored illustrations of eyes from sheep at different levels of anemia. The scale goes from 1 (mucous membranes are red) to 5 (mucous membranes are white); all animals are examined at regular intervals and only animals scored as being anemic are treated. In evaluation trials in South Africa, use of FAMACHA© reduced the number of dewormer treatments given by up to 90% as compared to previous years.

FAMACHA© cards are only to be sold directly to veterinarians or other trained animal health professionals. These individuals are expected to provide training in the proper use of the FAMACHA© system prior to re-selling the cards. The exception to this will be when sheep or goat producers attend a formal FAMACHA© training workshop.

If you are interested in learning more about FAMACHA©, please see the SCSRPC website at www.scsrpc.org or send an email to fosters@unce.unr.edu or call me at 775-273-2923 to request more information. If you would like to receive up-to-date information on other topics just email me a message and I will subscribe you to our Extension email list.

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