Schistosomus reflexus syndrome: a heritable defect in ruminants.

Schistosomus reflexus (SR) is a rare and fatal congenital disorder. Primarily observed in ruminants, its defining features include spinal inversion, exposure of the abdominal viscera because of a fissure of the ventral abdominal wall, limb ankylosis, positioning of the limbs adjacent to the skull and, lung and diaphragm hypoplasia. Variable components of SR include scoliosis, cleft sternum, exposure of thoracic viscera, and abnormalities of the digestive and urogenital systems. This report presents the findings from an anatomical analysis of a female Holstein SR calf with thoracoschisis, scoliosis and anomalies of the appendicular skeleton, cardiovascular, respiratory, digestive and urogenital systems. Many of these malformations have not been previously reported. The reproductive tract of this case is particularly unique, displaying Muellerian duct abnormalities. These abnormalities suggest SR occurs as early as the post-gastrulation embryo and involves the intermediate mesoderm. Preliminary analysis of associated cases suggests that SR has a genetic aetiology.