Johne’s disease (JD) is one of the important diseases of ruminants, which is capable of causing major economic losses to farmers in terms of decline in productivity. JD is very difficult to treat if once entered in livestock farms. It is a chronic granulomatous enteric infection of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). This organism was first reported by Johne and Frothingham in 1985. This infection is most often seen among domestic ruminants (cattle, sheep, goats, buffaloes and camels) as well as in wild ruminants. The disease has been reported in non-ruminants (pigs, horses, fox, lab animals) also.