A Test for the Detection of Equine Small Strongyles; Supporting Sustainable Worm Control in Practice

A study will be performed to generate sera and saliva for test validation. A parasitology research herd will be utilized. This herd has been kept without anthelmintic intervention since 1979 and comprises 20 mares and one stallion. The herd is kept with access to pasture year.round. Between 10 and 15 foals are born each year; these are humanely euthanized with full enumeration of parasite burdens as a part of an ongoing long.term transmission study. Here, and saliva will be collected from adult s and foals on a monthly basis through one calendar year. Serum will be collected by jugular venepuncture and saliva collected using EquiSal Saliva Collection KitsTM (Austin Davis Biologics Ltd). The sample will be recovered from the device by and stored in preservative solution (PBS, 0.1% Tween 20, 0.05% BND, 0.05% sodium azide). After processing, all samples will be labelled and stored at .20¢ªC. Foals are usually born March.July and will enter the study as they arrive. A necropsy schedule will be designed for foals to ensure an approximate age range of 3.12 months. On necropsy, large intestines will be removed and divided into cecum, ventral colon and dorsal colon. Organs will be opened separately and contents collected in separate containers. Duplicate 1% aliquots of contents will be collected and stored in labelled containers with an equal volume of 10% formalin. Each aliquot will be examined at 10X to 40X magnification to recover individual nematodes. These will be counted and preserved in 10% formalin. All specimens will be examined microscopically by trained personnel and identified to genus, species and stage using morphological criteria. The three large intestinal sections will be weighed and a longitudinal haustral section comprising 5% the total weight, will be excised from each section. The mucosa will be removed from each segment by scraping with a glass slide and digested in pepsin/HCl at 37¢ªC for 3 h. A 2% aliquot of digested mucosa will be examined at 30X magnification for enumeration of cyathostomin larvae. These will be classified as EL3 or late third/fourth stage larvae (LL3/L4). Estimates of mucosal larval populations will be calculated for each section based on the proportion of the analysed aliquots. Monthly serum samples will be used to inform on dynamics of antigen.specific IgG(T) over the course of the season (from birth to necropsy). Sera and saliva will be used to compare antigen.specific IgG(T) levels in the two biological compartments. Derived worm count data will be used in correlation studies with antigen.specific IgG(T) measured in terminal samples to compare level of antibody with level of total worm, EL3, LL3/L4 burden.