According to Charles Frédéric Heusinger (1853), dog distemper had been imported from Peru into Spain in the course of the 17th century. The disease was well described in 1746 by Ulloa in his work Relación histórica del viaje a la América meridional. During the course of the 1760s, the disease was reported in Spain, followed by England, Italy (1764) and Russia (1770). In 1763, 900 dogs died in a single day in Madrid. In 1844, Karle succeeded in the first experimental transmission of the disease by brushing the lips of young dogs with the discharge from sick animals. The causal agent of the disease was only discovered in 1905, when the virus was isolated by Henri Carré. In the meantime, Edward Jenner, who thought that the disease was a pox-like affection, claimed that it could be prevented by inoculation of the vaccinia virus.