Hemoglobinuric nephrosis in a rhea (Rhea americana)

An eighteen-month-old female rhea (Rhea americana) was presented dead for necropsy. The owner reported having observed blood in the droppings. Gross examination revealed a rhea in good body condition with a copious amount of frank blood in the cloaca. Large masses of matted fescue grass (Festuca spp.) distended the ventriculus and jejunum. No hemorrhage was evident in the digestive tract, which was otherwise void of ingesta. The kidneys were dark brown in color. Renal histopathology revealed a severe accumulation of eosinophilic pigment in the tubular epithelial cells of the proximal convoluted tubules, with tubular nephrosis and eosinophilic casts in the collecting tubules. It was concluded that the renal pigment was hemoglobin and not myoglobin, based on lack of evidence of muscle injury and the severe erythrophagocytosis evident in hepatic macrophages. The renal pigment also stained positive with the hemoglobin-specific Okajima stain. Hemoglobinuric nephrosis has not previously been reported in an avian species.