 It was experimentally transplanted between dogs in 1876 by M. A. Novinsky (1841–1914).A single malignant clone of CTVT cells has colonized dogs worldwide, representing the oldest known malignant cell line in continuous propagation, a fact that was uncovered in 2006.Researchers deduced that the CTVT went through 2 million mutations to reach its actual state, and inferred it started to develop in ancient dog species 11 000 years ago.