Pathological investigation of the mortality in captive Grasscutter (Thryonomys swinderianus) colonies in Accra, Ghana

Hepatorenal syndrome and clinical signs of heart failure occurred sporadically in 3- to 12-month-old Grasscutter(Thryonomys swinderianus) in captive colonies originally derived from in-bred male and female littermates. Macroscopic lesions in severely affected animals included subcutaneous edema, cervical swelling, pneumonia and hepatomegaly. 43 Grasscutters that were found dead and or were euthanatized because of dyspenia and lethargy were necropsied and representative blocks of tissues from heart, lungs, kidneys, liver and neck examined microscopically. Myocardial lesions were present in all rats and consisted of multifocalcardiac myocyte necrosis, and mononuclear inflammatory cell infiltration. 60% of the dead Grasscutters had chronic pulmonary congestion, and microscopically, livers showed chronic passive congestion. The kidneys showed tubular cell damage that appeared to be the central event in the pathogenesis of renal dysfunction and injury in Grasscutter, as evidenced by endothelial cell swelling, detachment, and accumulation of cast in the renal tubules. Swelling of the neck in these colonies of Grasscutter appeared to have resulted predominantly from unknown reasons possibly caused by stasis of venous blood secondary to right heart failure associated with a heritable cardiomyopathy.