Canine distemper is a very contagious viral disease that predominantly strikes young dogs.
It used to be common, but due to the practice of vaccinating young dogs it is now rare in most locations. Canine distemper is a Morbillivirus from the virus family Paramyxoviridae, subfamily Paramyxovirinae. It is an enveloped virus, and its nucleocapsid is recognized as having a distinct herringbone-shaped pattern. The viral genome is a negative sense single strand molecule of RNA with 15 to 16 kilobases. There are thought to be 6 genes within this molecule.