Findings from an ovine parasitological monitoring service provided by a rural veterinary practice in N ew S outh W ales, A ustralia

Objective To describe an ovine parasitological monitoring service delivered by a rural veterinary practice and determine associations between flock, anthelmintic and monitoring factors and worm control. Design Retrospective study of records from a rural veterinary practice in south‐eastern Australia over an 8.75‐year period. Methods Records of sheep producers using veterinary services for gastrointestinal parasite management from 1 August 2003 to 30 April 2012 were analysed. Results from pre‐ ( FEC t1 ) and post‐treatment faecal egg counts ( FEC t2 ) were used to identify factors influencing anthelmintic effectiveness, calculated as faecal egg count reduction percentage ( FECR %) by linear mixed model analyses. The trends in anthelmintic merchandising and uptake of veterinary services for parasite management were determined by logistic regression analyses. Results FECR % varied according to the treatment group used ( P < 0.001), with an apparent decreasing effectiveness of the macrocylic lactone group over the duration of the study ( P = 0.008). Wether and ram flocks displayed lower FECR % than ewe flocks ( P < 0.05). Time between FEC t1 and treatment ( P = 0.031), as well as time between treatment and FEC t2 ( P < 0.001), had a significant negative association with FECR %. The proportion of properties purchasing 4‐way combination anthelmintics increased significantly over the study period ( P < 0.001), with declines observed in other anthelmintics ( P < 0.05). The proportion of properties performing FECR % monitoring to those that purchased anthelmintics increased significantly over the study period ( P = 0.001). Conclusion Anthelmintic treatment type, sex of the flock and time between drenching and testing had the greatest influence on drench effectiveness ( FECR %). An increasing reliance on 4‐way combination drenches to manage gastrointestinal parasitism was demonstrated. Benefits of parasitological monitoring include: appropriate advice on parasitological management; observations on trends in regional anthelmintic usage; estimation of drench effectiveness; early indication of anthelmintic resistance; and improved service provision by the rural veterinary practice.