Background and Objectives: Parasites of digestive system of horses not only affect health and production of the animals but also might be important in regards to public health. This study aimed to determine the prevalence of gastro-intestinal parasites of horses in five counties of Hamedan and Arak provinces. Methodology: From May to June 2019, totally 40 fecal samples from horses of both sexes and different ages for detection of gastrointestinal parasites were examined. Samples were collected from four counties of Hamedan province (Hamedan, Bahar, Razan, Malayer; n=27) and one county of Markazi province (Khondab; n=13). The samples were subjected to Clayton-Lane method using saturate sodium chloride solutions and sugar saturated solutions and examined microscopically. Results: Twenty horses (50%) were infected with eggs or oocysts of parasites. Twelve horses (60%) were infected with a single species and 8 (20%) had infections with two species. The most prevalent parasite species was Parascaris sp. (42.5%) followed by Dicrocoelium dendriticum (10%), Eimeria leukarti (5%), Strongylus-type egg (2.5%) and Schistosoma turkestanicum 1 horse (2.5%). Discussion and Conclusion: Results of this study suggests that high rate of infection with gastrointestinal parasites could contribute to low performance and life expectancy of working horses in these regions.This study is the first report about gastrointestinal parasite in horses in these regions.
