Internal Parasite Infestations and “Deworming”

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Unfortunately, with the gorgeous weather and warm temperatures comes an issue that all livestock producers face in their herds. This is the infestation of internal parasites or “worms.” Many producers treat their animals with an antiparasitic on a routine schedule to help avoid the complications that can arise in livestock that are infested with internal parasites. Unfortunately, these routine schedules can contribute to antiparasitic resistance. This allows the parasites to live through the treatment. When this occurs, the surviving parasites reproduce. This makes the anti-parasitic useless.

To avoid resistance from occurring in our herds, a practice called “fecal egg count determination” is used. This practice can be used on all species of livestock. This practice involves a producer collecting fresh samples of feces from livestock and examining the feces under a microscope. In doing so, the producer will be able to identify the number and type of internal parasites that are infesting their livestock. By identifying and counting the individual parasite eggs on the slide, the producer can then determine the degree to which their livestock is infested by internal parasites.

By using this method of determining the number of parasites that are actively infesting livestock, producers can make better judgements as to when they should treat their animals for internal parasites. Research has suggested that producers not treat their animals with an antiparasitic or “dewormer” until the fecal egg count reaches a certain threshold. Species, age, and reproductive status of the animal helps determine this threshold. In waiting until this threshold is met to treat with an antiparasitic, producers are decreasing the number of resistant parasites. This method is used alongside the more commonly used method of identifying any physical symptoms of internal parasite infestation such as rough hair coat, loose feces, lethargy, etc.

Due to the need for a microscope to accurately utilize the fecal egg count method, it is easier for producers to gather the fecal samples from their livestock and bring the samples to their local veterinarian or Livestock agent for proper analysis.

If you have livestock and would like to determine if antiparasitic treatment is advised, please contact Michelle South, Extension Agent- Livestock, at the N.C. Cooperative Extension, Avery County Center at 828-733-8270 to set up an appointment to analyze your livestock’s fecal samples.