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Title: EFFICACY OF A POUR-ON FORMULATION OF EPRINOMECTIN (MK-397) AGAINST NEMATODE PARASITES OF CATTLE WITH EMPHASIS ON INHIBITED EARLY FOURTH-STAGE LARVAE OF OSTERTAGIA SPP

Author
item WILLIAMS, J - LOUISIANA STATE UNIV
item Stuedemann, John
item BAIRDEN, K - U OF GLASGOW, SCOTLAND
item KERBOEUF, D - INRA, NOUZILLY, FRANCE
item CIORDIA, H - UNIVERSITY OF GEORGIA
item HUBERT, J - INRA, NOUZILLY, FRANCE
item BROUSSARD, S - LOUISIANA STATE UNIV
item PLUE, R - MERCK & CO
item ALVA-VALDEZ, R - MERCK & CO
item BAGGOT, D - MERCK & CO

Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Presence of internal parasites in the gastrointestinal tract of cattle can result in clinical signs and more importantly reduced productivity. Administration of many dewormers require intensive handling of animals, particularly those that are given orally. As resistance to existing dewormers develops, it is important that efficacious new products become available for producers to control parasites. Eprinomectin is a new dewormer that was developed for topical application, making it relatively easy to administer, that is very efficacious against all form of gastrointestinal parasites.

Technical Abstract: Four experiments were conducted for evaluation of the anthelmintic activity of topically applied eprinomectin against naturally acquired infections of early fourth stage-larvae (IL4) of Ostertagia spp. on cattle. Two dose titration studies examined drug concentrations of 125, 250, and 500 ug/kg body weight in Louisiana and Georgia. Confirmation studies of the selected therapeutic dosage (500 ug/kg) were conducted in Scotland and France. Results at the four locations demonstrated a consistently high level of efficacy of eprinomectin at 500 ug/kg in removal of Ostertagia IL4. Inhibition percentage was uniformly high, being 80, 68, 68, and 73% for Louisiana, Georgia, Scotland, and France, respectively. Ostertagia and Cooperia were the only common genera across all sites, and efficacy levels against adult and larval stages of both genera were consistently high at >99%. Results of one or both titration studies (500 ug/kg) indicated > 99 to 100% efficacy against adult Hemonchus placei, Trichostrongylus axei, T. colubriformis, Bunostomum phlebotomum, Dictyocaulus viviparus, and Oesophagostomum radiatum. Lower efficacy values were observed at the minimal (125 ug/kg) daosage. Adverse reactions were not evident. These studies confirm that eprinomectin given topically (500 ug/kg) was highly effective against Ostertagia IL4 and other common nematodes of cattle.