Neospora caninum is a coccidian parasite of animals. It is a major cause of abortion in cattle in many countries. Domestic dogs and coyotes are the only known definitive hosts for N caninum. It is one of the most efficiently transmitted infections of cattle, and up to 90% of cattle in some herds are infected. Transplacental transmission is considered the major route of transmission of N caninum in cattle. There is no proven vaccine to prevent N caninum abortion.