Managing Your Farm's Parasite Portfolio

Managing Your Farm's Parasite Portfolio

Hertzberg and his team found that, of the 400 horses monitored over the past year, only 10% needed treatment against strongyle infestation.

Photo: Megan Arszman

Have you managed your farm's parasite portfolio lately? If not, it might be time to pick up on this new Swiss trend.

By analyzing each farm's portfolio—or, the parasite load based on fecal egg counts, management systems, kind of farm (sport, leisure, breeding, etc.)—specialized equine health organizations now offer Swiss horse owners a parasite control method that’s effective and cost-efficient, said Hubertus Hertzberg, PhD, researcher at the Institute of Parasitology of the Vetsuisse Faculty at the University of Zurich and head of parasite monitoring at HealthBalance, a private holistic animal management and veterinary practice, based in Niederuzwil.

Over the past year, Hertzberg and his fellow researchers have made parasite portfolio discoveries that are both satisfying and surprising. He presented this research at the 2014 Swiss Equine Research Day held April 10 in Avenches.

The team learned there are fewer small strongyle (cyathostomins) infestations, but more roundworm (Parascaris equorum) infestations in Swiss adult horses than they expected, he said. Plus, with proper management and “parasite portfolio” monitoring, significantly fewer adult horses in the program had to be treated for intestinal parasites, he said.

“Our data reinforce what has already been outlined in previous studies and makes it clear that the flat-rate treatment of all horses in today’s epidemiological situation is no longer compatible with effective parasite management,” Hertzberg said.

Hertzberg and his team found that, of the 400 horses monitored over the past year, only 10% needed treatment against strongyle infestation, despite a “very low” threshold for treatment—only 200 eggs per gram (epg) of feces, he said. In fact, in 79% of the samples they found no strongyle eggs at all (with a 50 epg sensitivity test).

On the flip side, however, many more stables had roundworm-infested adult horses than anticipated, since roundworms are typically seen primarily in young horses, he said. In the first monitoring year, 22% of the investigated stables housed roundworm-positive horses aged 4 years and older.

“What’s particularly critical here is that at least half these horses had recently been treated with the latest generation of deworming medications (ivermectin, moxidectin, for example), but their efficacy was not sufficient,” Hertzberg said. “This new development underlines the importance of ‘portfolio’-specific control measures and a regular review of resistance status.”

Preventing resistance is of particular importance when dealing with breeding stock, as young horses must still be dewormed according to a classic rotational method because they are more vulnerable to internal parasite infection than adult horses, possibly with fecal egg counts as an “accompanying tool,” he added. Keeping worms from becoming resistant in adult horses will, therefore, keep younger horses better protected against the parasites.

In Switzerland, parasite portfolio management is becoming more commonplace—partly because of a strong awareness campaign by the country’s two veterinary schools and partly because of parasite management organizations (which provide full-range on-site monitoring of horse farms [egg counts, larval culture, control samples after treatment, quarantine samples, detailed analyses of the farm situation, and consultations] for a flat annual fee) that make the process easier for owners, Hertzberg said. Even certain veterinary pharmaceutical companies are supporting the effort, “which is quite remarkable for an industry partner,” he added.

Hertzberg’s parasite portfolio management study received the 2014 Research Prize at the Swiss Equine Research Day.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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