Factors influencing the magnitude of strongyle egg-shedding in horses

Abstract

simultaneously at frequent intervals is still common in Finland, even though horse practitioners are now promoting the use of targeted selective treatment. In order to evaluate selective therapy as an option to reduce anthelmintic use we conducted a study on ten stables. Objectives: 1. To estimate parasite loads of individual horses 2. To analyse risk factors for high egg counts 3. To observe the effects of different anthelmintics to the individual parasite loads. One to eight fecal samples per horse were collected from 215 (86 geldings, 100 mares, 24 stallions) horses (mean age 9.1 yrs, min 0 and max 29) from ten stables in Finland during a one-year study period. The samples were analysed by modified McMaster-technique by the Finnish Food Safety Authority (Evira). Antiparasitic treatment history of each horse was collected by a questionnaire. Majority of the adult horses maintained low epg-values ( 20 years). Majority of the adult horses are able to maintain low epgvalues and therefore frequent treatments with anthelmintics to all horses should be discouraged. Horses should be sampled and treated based on individual risk factors and epg-values. Further analysis of the data will bring more information on how the risk of high epg-count is affected by grazing, season and treatment intervals.