Fatal Haemonchosis in Sheep, Incidence, Post-Mortem and Histopathological Investigation

Abstract

Haemonchosis, caused by the blood-feeding nematode Haemonchus contortus, continues to be a major health problem in sheep and goat,  especially in tropical and subtropical regions. The present study investigated the incidence and histopathological changes associated with H.  contortus infection in sheep under field conditions. A total of 60 sheep that died with a history of diarrhoea and progressive weakness were  subjected to necropsy at Department of Veterinary Pathology of the College in Hyderabad during September 2025 to March 2026. Among  them, 34 sheep were positive for H. contortus. Post-mortem examination of the affected sheep consistently revealed pale mucous membranes,  mild ascites, watery blood, and worms in the abomasum. The abomasal mucosa showed congestion, petechial haemorrhages, and catarrhal  inflammation. Microscopically, abomasal sections showed mucosal edema, haemorrhage, epithelial degeneration, and infiltration of inflammatory  cells, predominantly eosinophils and lymphocytes. The recovered parasites were identified as H. contortus based on characteristic morphological  features, including the “barber pole” appearance of female worms. This study confirms that acute haemonchosis can lead to severe anaemia and  hypovolemic shock, resulting in sudden death. These findings highlight the importance of early diagnosis, routine monitoring, and strategic  parasite control measures to reduce production losses in sheep.