title: Delay in timing of the oxfendazole pulse release bolus in calves in The Netherlands.
abstract: The efficacy of the oxfendazole pulse release bolus (OPRB) was tested in a grazing experiment at the University of Utrecht. Three groups of four OPRB-treated calves and one group of four untreated control calves were grazed on separate pastures between 18 May and 21 October 1987. Based on faecal egg counts for strongyle-type eggs and Nematodirus eggs, embryonation of Nematodirus eggs and faecal larval counts for lungworm, the first pulse of oxfendazole was released after 28 to 63 days, which was later than the period of approximately three weeks indicated by the manufacturer and others. As far as could be detected, the second to fifth pulses were not as delayed, but generally the three-week period was also exceeded. This delayed release of the pulse resulted in a build-up of pasture infectivity for gastrointestinal nematode larvae and lungworm larvae. Nevertheless, this did not result in clinical gastrointestinal helminthiasis and husk in the treated groups of calves, whereas severe husk and mild gastrointestinal helminthiasis were seen in the control group.
authors.affiliation: Department of Infectious Diseases and Immunology, University of Utrecht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Eysker
authors.forename: J H
authors.initials: JH
authors.lastname: Boersema
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D003692:Delayed-Action Preparations; D004021:Dictyocaulus; D005243:Feces / Q000469:parasitology; D005260:Female; D009349:Nematode Infections / Q000517:prevention & control / Q000662:veterinary*; D009426:Netherlands; D010270:Parasite Egg Count; D013997:Time Factors
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D003692:Delayed-Action Preparations; C011030:oxfendazole