Protecting livestock from Infections

The summer months pose a variety of challenges for livestock operations. During the heat of early summer producers will want to keep an eye out for any signs of parasitic infections in their flocks or herds. 

Moisture and Heat

Parasites prefer and thrive in moisture. Their eggs hatch and mature in moist manure. Though the scorching summer rays can bring heat stress to livestock, there is a benefit to hot, dry days. The parasitic eggs cannot hatch into larva if they dry out. The summer heat helps to deplete the parasite population.

Signs of Infection

Though the sun plays a role in reducing the parasitic population, the problem with parasites in a herd or flock can persist. “Signs of parasitic infections are diarrhea, weight loss or going off feed,” Heidi Ward, DVM, Ph.D., veterinarian and assistant professor associated with the University of Arkansas Cooperative Extension Service, explained. “If severe, animals may show open mouth breathing and may suddenly die from cardiac collapse due to anemia.” 

Treatment for Parasitic Infections

In the case of parasitic infections, not all the animals in a producer’s herd or flock will need treatment. Veterinarians state healthy adult animals can manage internal parasites with efficiency. 

Therefore, veterinarians recommend targeted treatment. Producers should focus their treatment efforts on young animals and adults with large parasite burdens. “The healthy adults are untreated so that any parasite eggs that pass in their manure can compete with eggs from drug-resistant parasites,” Ward explained.

If producers leave a small population of parasites untreated, this creates an environment in which there are always some parasites in the overall population that are susceptible to treatment. Continuing to treat all cases and killing all susceptible parasites produces a scenario in which the treatment strategy leaves behind more and more drug-resistant parasites. 

Fecal Egg Count

In order to get an accurate assessment of the parasite burden in a herd or flock, producers can collect fecal samples to be analyzed. Producers can either take a fecal sample to their veterinarian or perform a fecal egg count (FEC) on their own to determine the worm burden of a specific animal. 

For more information on the proper way to conduct FECs, the University of Arkansas Cooperative Extension Service hosts several workshops each year to teach producers how to perform FECs. “A fecal egg count reduction test (FECRT) is the only way to find out if the population of parasites in the herd or flock are resistant to a particular parasiticide,” Ward said. To perform the test, an FEC is conducted prior to administering the parasiticide. After two weeks, another FEC is conducted to see if the treatment significantly reduced the eggs passed in the feces.


Dr. Ward also shared that there is no way to completely remove internal parasites from an animal that lives on pasture. Instead, treatment is aimed at reducing the number of parasites to be managed better by the animal’s immune system. Proper herd and flock management, nutrition and vaccinations are all factors in producing healthy animals that can handle parasitic infections.


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