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This decision making support tool is designed to help sheep and goat producers sort through the large amount of information available on controlling sheep and goat parasites and make decisions about specific management options that are relevant to their farm operation. It is not intended to be prescriptive or replace your veterinarian with regard to diagnosis of parasitism or specifics of drug use. We believe parasite control programs should be developed at the farm level. The information has been organized in a "decision tree" or "flow chart" approach where answering one question leads to another question or various management options.
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Videos created by Dr. Cliff Monahan, OSU Veterinary Parasitologist
This video shows a tangled mass of adult Haemonchus contortus worms as found in the abomasal (stomach) contents of a sheep that had died of blood loss created by massive infection with these worms. Enormous numbers of these worms were found in the stomach contents. A blood clot helps hold this mass of worms together. As the tangled mass is teased apart, you can see the individual worms and their “barber pole” appearance caused by the worm’s blood-filled gut spiraling around the large uterus.
In this video you can watch through the microscope as worm eggs undergo changes toward hatching into the first stage larva and then to the final, or third stage, larva which is infectious for sheep and goats. The third stage larva has a rough or “corrugated-like” appearance to its outer surface. The process of egg development to infective third stage larva can occur in as little as 4 days under ideal conditions. More commonly it takes about 7 days.
In this video, you can watch as the microscope zooms in on the contents of three individual wells of the DrenchRite® Assay plate. You will see worm larvae that have developed from eggs and a few eggs that did not develop. In this assay, a known number of worm eggs are placed in each of the 96 wells, or cavities, of the plastic plate. Each well contains some nutrients and moisture to support the development of worm larvae to the infectious third stage (L3). The wells contain varying concentrations of dewormers, and the number of larvae developing to the third stage is compared to the number developing in control wells that have no dewormer. In this way, resistance to the three classes of dewormer can be detected.