Tips for: Treating Internal Parasites

By Linda Coffey, NCAT Agriculture Specialist



Photo: Jean-Marie Luginbuhl

Internal parasites are a common health problem for grazing livestock, especially sheep and goats. There are a number of effective management practices to lessen the risk (see ATTRA’s Tips for Preventing Internal Parasites) and others that can reduce the need for treatments (see ATTRA’s Tips for Managing Internal Parasites). When those measures are not enough to prevent illness, however, producers will need to treat animals to bring them back to health. This tipsheet identifies ways to more effectively treat animals suffering from internal parasitism.

Treat only those animals that are indeed suffering. Treating everyone in the flock or herd is expensive, ineffective, and leads to accelerated dewormer resistance.

Have a valid relationship with a veterinarian. A veterinarian will be helpful for diagnosing, and if extra-label drug use is necessary, you must be working with a veterinarian to comply with the law. See ATTRA’s Tips for Working with a Veterinarian.

Diagnose. Is the animal suffering from gastrointestinal parasites, or coccidiosis? Dewormers will not be effective treatments for coccidiosis. Your veterinarian can help differentiate, although sometimes an animal will be infected with both. See the American Consortium for Small Ruminant Parasite Control and Maryland Small Ruminant Page for more information.

Give the animal good supportive care. Plenty of good-quality forage—especially dry hay—and clean, fresh water. Handle the animal calmly and gently and provide shade.

Choose an effective medication.

  • The DrenchRite assay test will identify which dewormers will work on your farm, and which will not.
  • Fecal Egg Count Reduction Test (FECRT)—compare fecal samples taken before treatment with one taken 10 to 14 days after treatment. If the drug is effective, egg counts should be reduced by 95%.

Use Smart Drenching techniques.

  • Dose by weight; never under-dose.
  • Dose goats at 1 ½ to 2 times sheep dose (depending on the drug; remember to consult your veterinarian).
  • Fast animals overnight to increase medication effectiveness.
  • Deliver dewormer over the tongue and into the back of the throat. If the dose is not swallowed, it will not be effective.

Keep records. You need to know what animals required deworming, what dewormers and dosages were used, and how many treatments were required in the grazing season. This is valuable information that can help make future decisions more effective.

Adjust management. When you have to deworm animals, figure out why. Do you need to improve grazing management? Offer better nutrition, especially mineral mix and good forage? Are your animals being stressed in some way? Does sanitation need to be improved? The goal is to prevent illness, and management is key.

Cull animals that are not able to fight internal parasites, and select those stronger, healthier animals for breeding. This is especially important when selecting sires for the herd or flock.

Follow up to ensure that deworming was effective. Conduct FECRT.

With attention to management and culling, the number of needed treatments can be reduced. By only treating those animals that need it, using effective treatments in an effective way, culling weaker animals, and adjusting management to support the immune system and avoid consuming parasite larvae, grazing animals can be kept healthy, productive, and profitable.

Further Resources

The American Consortium for Small Ruminant Parasite Control provides up-to-date information regarding every aspect of internal-parasite control. More information about Smart Drenching may be found there. Dewormer charts are provided, as well.

Langston University includes a Web-based training course with Chapter 7 focusing on internal and external parasite control.

Tips for Treating Internal Parasites
By Linda Coffey, NCAT Agriculture Specialist
Published April 2015
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This publication is produced by the National Center for Appropriate Technology through the ATTRA Sustainable Agriculture program, under a cooperative agreement with USDA Rural Development. This publication was also made possible in part by funding from the USDA, NIFA Organic Research and Education Initiative, project 2010-51300-21641. ATTRA.NCAT.ORG.