A case of chronic schistosomiasis in a Dongola stallion (Equus ferus caballus Linnaeus, 1758) from Nigeria

Schistosomiasis is a worldwide snail-borne parasitic infestation of man and animals with acute or chronic phases having devastating sequelae. The present case report focused on post-mortem examination of a cachexic Dongola stallion (Equus ferus caballus Linnaeus, 1758) in Abuja, Nigeria, that failed to respond to treatment. Typical dense collagenous granulomatous lesions with marked inflammatory responses and fibrosis occurred in the liver and several visceral organs of the horse along with other lesions indicative of systemic collapse. Special Ziehl–Neelsen and Periodic Acid-Schiff staining as well as microbial culture returned negative results to rule out acid-fast bacilli, fungal, and other bacterial involvement. In addition, the presence of a yellowish-brown eggshell within fibrosing granulomatous lesions led to the diagnosis of chronic schistosomiasis. Prolonged malnutrition under harsh and changing increment weather conditions with lack of medical care following the infection might have predisposed the horse to the recorded systemic collapse in the present case. The dearth of information on the ante-mortem evaluation of acute equine schistosomiasis cases notwithstanding, the observed lesions/cellular changes reinforced  associated multi-organ damages and systemic collapse in chronic cases. Our findings highlighted the pathological presentations and prognosis of chronic schistosomiasis and its triggers, especially in endemic areas, and in horses that often do not present obvious clinical manifestations.