[Veterinary double-monsters historically viewed]

A large number of duplication monstrosities have been observed in cattle, sheep, pigs, horses, goats, cats and dogs, ever since the publication of the famous woodcut of a swine double monster by J. S. Brant in Basel in 1496, better known as the "wunderbare Sau von Landser im Elsass". Albrecht Dürer also made a woodcut of this double monster in front of the village Landser in 1496. A picture of a deer double monster was published in 1603 by Heinrich Ulrich in Germany. In the monograph De monstrorum causis, natura et differentiis ..., published by the Italian Fortunius Licetus in 1616 pictures of double monsters being half man half dog are found. These fantasy figures have been popular for a long time and were supposed to be really in existence. Apart from these fantasy figures many pictures are known from real veterinary double monsters. U. Aldrovandus described in 1642 in his Monstrorum historia, besides many fantasy figures, also real human and veterinary double monsters and he gave also good pictures of them. In the 19th century examples of veterinary duplication monstrosities were published by I. Geoffroy Saint-Hilaire (1832-37), E. F. Gurlt (1832), W. Vrolik (1840) and C. Taruffi (1881); they proposed also concepts concerning the etiology. In the second volume of his famous handbook of teratology (1907), E. Schwalbe described many veterinary double monsters and discussed the theories of the genesis of congenital malformations. Various theories concerning the genesis of double monsters have been given since Aristotle (384-322 B.C.). ...