The piglet is born with a blind end to its rectum, 5-10mm in length with no anus. It is not worth attempting surgical repair. Death invariably ensues. The incidence in mature herds is usually less than 0.5% but it can be much higher in newly established gilt herds. The condition is heritable but of low penetrance. Records may indicate that a certain boar is involved. The abdomens of affected piglets becomes enlarged. Some piglets may survive to weaning. Affected piglets should be destroyed.