Time to deworm sheep and goats once again
Thursday, May 6, 2021
Media Contact: Donald Stotts | Agricultural Communications Services | 405-744-4079 | donald.stotts@okstate.edu
The arrival of May has signaled to sheep and goat producers that it is time to determine if they need to deworm their flocks and herds prior to the onset of hot, dry weather.
“Internal parasites in sheep and goats can be especially serious threats to animal health and production, and the barber pole worm is the worst of the lot,” said Dr. Barry Whitworth, Oklahoma State University Extension veterinarian and food animal quality and health specialist.
Recent news of a groundbreaking treatment developed by the U.S. Department of Agriculture’s Agriculture Research Service, Virginia Tech University and the University of Massachusetts’ Medical School to combat health issues associated with the barber pole worm has caught the attention of many producers. Research indicated the treatment significantly reduces fecal egg counts and adult worms. Whitworth recently provided additional insights about the treatment on the agricultural television show SUNUP.
“Unfortunately, the treatment is not available commercially,” he said. “Compounding the problem is the fact the barber pole worm has developed resistance to many known classes of anti-parasitic drugs. Still, the best bet for producers at this time is to go with tried-and-true measures.”
Oral drenching is a commonly used measure and the one most recommended by experts. Tramisol, levamisole and ivermectin are among the more popular chemical products for sheep; for goats, popular chemical products include albendazole, fenbendazole, ivermectin, levamisole and moxidectrin. Moxidectin will kill barber pole worm larvae for at least two weeks after drenching.
Most experts do not recommend deworming through feed or water. A third of the recipient animals tend to get too much treatment, a third get about the right amount and a third get too little of the product, Whitworth said. Using injectable dewormers in sheep and goats is not advised.
OSU Extension recommendations are for producers to consult with a veterinarian to develop the most effective plan possible for their specific operation, including measures to lessen resistance issues with stomach worms.
Another key measure is to monitor for parasite buildup on a routine basis. Whitworth cited as an example FAMANCHA, a commercially branded diagnostic tool to identify parasite infection in small ruminants such as sheep and goats. It matches the color inside an animal’s eyelids to anemia levels, an indicator of parasite infection. Not only does this tool allow producers to target treatment only to infected animals, it can significantly reduce the changes of causing parasites to become resistant to dewormers.
“The five-point check and fecal samples submitted to a veterinarian to get egg counts also are good ways to monitor parasites,” Whitworth said. “Monitoring should take place every two weeks during spring and early summer, and once a month during summer and winter.”
Don’t forget good pasture management. Sheep will graze a pasture close to the ground if allowed. Goats prefer leaves and tall growing plants, but likewise will graze a pasture close to the ground if tall vegetation is not present. That’s an important detail because worm larvae favor the bottom four inches of grass pastures and infest animals when consumed along with forage.
OSU Extension recommendations are to move sheep and goats off the pasture when the forage is at four inches. This will require frequent moving of their flocks and herds for many producers, but it is a good risk management strategy, Whitworth said.
Parasite larvae on pastures survive well in an environment that is moist and warm. When the temperature is between 45-85 degrees and there has been at least two inches of rainfall during the month, parasites will thrive and develop in a pasture. Studies have shown the ideal weather for the larvae is around 78 degrees with 85% humidity. Once ingested, the larvae develop into adult worms in the animal’s gut.
Barber pole worms get their name because of their appearance when seen in the abomasum, the fourth chamber in a sheep or goat’s stomach. The worm’s spiraling red gut looks similar to the striped pole historically seen outside barber shops.
Fact sheets detailing research-based information about best management practices for sheep and goats are available online through OSU Extension and at OSU Extension county offices.