An overview about canine distemper virus, its hosts and the pathogenesis of canine distemper virus (CDV) infection is given. Additionally, a short overview about the properties of CDV, clinical and pathological changes related to the virus is provided. Furthermore, the characteristics of the CDV strains R252 and Onderstepoort in vitro are described. The classification and clinicopathological features of canine parainfluenza virus (CPiV) are elucidated. Another part deals with the classification of canine histiocytic disorders, the comparison of canine histiocytic disorders regarding their cellular origin, most commonly affected organs and predisposed breeds. Additionally, a short overview about the characteristics of a canine histiocytic sarcoma cell line, termed DH82 cells, is given. Furthermore, mechanisms of anti-tumor effects, immune response and viral oncolysis are detailed. Finally, a review about cortactin structure, its interacting partners and its role in cell migration and invadopodia formation is given.