An Abattoir-based Survey of Helminthic Liver Infections and Associated Pathological Lesions in Sheep in the Sultanate of Oman

Importation of apparently clinically healthy animals from endemic areas to naïve countries is a major source of infection to the establishment of new pathogens outside borders. A survey investigation between 2018 and 2021 was conducted at the Central Muscat Municipality Slaughterhouse to examine parasitic infections in condemned liver from 948 sheep samples during routine meat inspection. Pathological and parasitological examinations were carried out to identify parasites and associated hepatic lesions. An overall prevalence of 6.01% (57/984) was observed in sheep condemned liver by single infection of Dicrocoelium dendriticum, Cysticercus tenuicollis, Stilesia hepatica, Fasciola hepatica, and hydatid cysts. Hepatic lesions varied widely from severe hemorrhagic wavy tracts in case of acute cysticercosis (0.4 %) to indurated dark brown with numerous white scars in livers infected with D. dendriticum (4.2 %). Presence of cysts with clear fluid and protoscoleces were seen in livers infected with C. tenuicollis (0.63%) and hydatidosis (0.1%), detected as larger cysts with white thicker walls embedded in livers. Examination of the bile ducts revealed S. hepatica at 0.4% and F. hepatica at 0.2%, with thickened bile ducts. Morphometric measurements confirmed the diagnosis of D. dendriticum in imported sheep from Romania. To the best of our knowledge, this is the first report of helminthic infections among sheep livers, with reference to dicrocoeliasis in imported sheep in Oman. Expanding of livestock based on animals’ importation warrants further quarantine regulations to control emerging parasites and to reduce economic losses due to liver condemnation in the country.