Deworming Strategies and Hurricane Recovery

The level of equine parasite transmission should be diminished on pastures evacuated due to flooding, said Craig Reinemeyer, DVM, PhD, president of East Tennessee Clinical Research in Knoxville, Tenn. "Many larvae would get washed away, and others would go down into the soil," he said. "In either case, climatic conditions now (early October) along the Gulf Coast aren't favorable for long-term survival of infective stages (the hotter it is, the quicker they die)."

Regrettably, Reinemeyer added, the infective stages aren't going to drown.

He noted that heavy precipitation will break down manure piles and distribute infective larvae throughout the pasture. "Of course, that takes place several times a year under normal climatic conditions, and only requires about 2 cm of water, not nine feet," he stated, adding that owners should deworm their horses on schedule.

New parasites might be introduced to your property. "It's possible that some parasites that were not native to your farm may come floating in from down the road," said Reinemeyer.

He recommended the following strategy for mature horses being returned to previously flooded pastures:

"This circumstance represents a unique opportunity to 'start over' with a pasture, so you want to use dewormers that are known to be effective in your herd. If you don't have specific information (such as a fecal egg count) for your farm, ivermectin and moxidectin consistently demonstrate very high efficacy against strongyles. Plus, both drugs are larvicidal, meaning they can kill the migrating stages of large strongyles that aren't susceptible to most dewormers.

"Reintroducing horses also represents an opportunity to eliminate tapeworms from the premises," Reinemeyer continued. "Owners could achieve both objectives by treating with a combination product that includes praziquantel plus ivermectin or moxidectin (ComboCare, EquiMax, Quest Plus, or Zimecterin Gold). No de-wormer can eradicate the small strongyles within a horse, however, so an effective control program should be followed after reintroduction. (See

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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