DULUTH, Ga. — August 2010 —Bluntly challenging more than four decades of conventional wisdom, Merial today announced a new equine educational campaign urging horse owners to stop arbitrarily utilizing year-round or rotational deworming programs.
Instead, horse owners and veterinarians should collaborate to apply the dwindling supply of effective deworming products more strategically – and more effectively.

“Multiple studies from across the country have shown entire classes of dewormers are no longer working against small strongyles,”1,2,3 said Frank Hurtig, DVM, MBA, director for Merial’s Large Animal Veterinary Services. “Most horse owners think they have been doing the right thing to fight resistance by using a daily product or rotating dewormers. But indications are strong that these practices may contribute to resistance.4,5
“After four decades of little or no progress, it’s time for the industry to rethink daily deworming and dewormer rotation,” says Dr. Hurtig.

Horse owners should stop routinely deworming based on the calendar, tradition, peer recommendations or dewormer sale price, advises Merial’s new “Greetings, Human” educational campaign. They should instead seek out a knowledgeable equine veterinarian to help them develop long-term, effective deworming protocols based on monitoring and management.6

"Our educational campaign humorously recognizes that if worms could talk, they’d in fact be telling us to keep on doing exactly what we’ve been doing for decades,” says Dr. Hurtig. “In the long run, unfortunately, it’s actually better for the worms if horse owners continue to deworm the way most have been. The last thing a resistant small strongyle would want is for us to become more strategic in deworming.”4,7

Strategic guidance from knowledgeable veterinarians is the critical missing link preventing too many farms from effectively managing their parasite populations,6 he says. “There are about 50 species of small strongyles that can infect grazing horses.8 Eliminating all worms from all horses and pastures on a farm is a futile goal. A much more worthy target is to maintain a low level of parasites on a farm with a large proportion of those parasites being highly susceptible to the dewormer(s) being used – an approach also known as refugia1,4,7,9

It is important to remember most of the parasites are on the pasture and about 20 percent of the horses on a farm put out about 80 percent of the worm eggs to contaminate those pastures.4,5 Working with your veterinarian to identify these “high shedders” and then tailoring your deworming to target these horses with more effective products, while reducing treatments of the remaining horses, is the best approach to obtaining optimum worm control on your farm.” 7,10,11,12

This approach can be a significant departure from what drug companies, scientists and veterinarians have counseled in the past – urging horse owners to use daily dewormers or rotate deworming compounds from different classes based on a set calendar schedule. With new data, better understanding of products and how they work, and increasing evidence of parasite resistance, many in the equine industry are changing their approach to equine deworming.

He proposes that horse owners adopt refugia as a new goal for parasite control on their farms. All the other reasons for which we use dewormers will become immaterial if this goal is not achieved. This means we must become better stewards to preserve the effectiveness of current products. Prudent use of deworming compounds requires us to be more targeted, more strategic and more judicious. Our job now is to keep the effective dewormers as effective as possible for as long as possible. Daily deworming and continual rotation will not do that.4,10,11,13

“Think about it this way: You would never randomly use an antibiotic to blindly treat an undiagnosed and inapparent infection,” Dr.Hurtig says. “This practice wastes time and money, and it increases the risk for developing resistant pathogens. The same attitude must now be brought to bear against increasingly resistant parasites in dewormer selection.”
Dr. Hurtig suggests horse owners ask their equine veterinarian about a targeted testing, treatment and management program for their operation, or go to www.zimecterin.com for more information about parasite resistance (see the parasite resistance tab on the home page) and Merial’s new “Greetings, Human” educational campaign.

About ZIMECTERIN GOLD
ZIMECTERIN Gold combines ivermectin, a leading ingredient that controls a wide variety of parasites, with praziquantel, an ingredient that specifically controls tapeworms. Together, they provide excellent equine parasite control. ZIMECTERIN Gold is approved to control more species and stages of equine parasites than any other brand, including benzimidazole-resistant small strongyles.14 It controls 47 species and stages of equine parasites in all.14

Plus, ZIMECTERIN Gold was the first dewormer approved by the FDA to effectively control tapeworms* with a single dose. Tapeworms have been recognized as a significant threat to the health of horses.15
About MERIAL
Merial is a world-leading, innovation-driven animal health company, providing a comprehensive range of products to enhance the health, well-being and performance of a wide range of animals. Merial employs approximately 5,700 people and operates in more than 150 countries worldwide. Its 2009 sales were $2.6 billion. Merial is the Animal Health subsidiary of sanofi-aventis.
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Important Safety Information
Warning: Not for use in humans. Keep this and all drugs out of reach of children. In horses, there have been rare reports of swelling and irritation of the mouth, lips, and tongue following administration of ZIMECTERIN Gold. These reactions have been transitory in nature. Do not use in other animal species as severe adverse reactions, including fatalities in dogs, may result.

®ZIMECTERIN is a registered trademark of Merial Limited.
©2010 Merial Limited, Duluth, GA. All rights reserved. EQUIZIM1016 (06/10)

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