Leptospirosis is a zoonosis of worldwide distribution, caused by Leptospira interrogans. It is a well known cause of bovine reproductive losses such as abortion, infertility, stillbirth and birth of weak calves. In
this research, the relationship between the seroprevalence rate of Leptospira spp. infection and abortion in
industrial dairy farms of Hamedan province, Iran was studied. A total of 80 blood samples were taken from
aborted cows in six dairy farms. Sera were tested for antibodies against 6 serovars of Leptospira interrogans
(hardjo, pomona, canicola, grippotyphosa, icterohaemorrhagiae and ballum) using microscopic agglutination test (MAT). Antibodies were detected in 18 (22.5%) of the aborted cows, including 17 (21.25%) against L. canicola and 1 (1.25%) against L. pomona. It is concluded that dogs (shepherd and stray) and wild carnivores may have an important role to maintain and transmit the L. canicola infection to the cattle population in this region, therefore, vaccination of cattle and shepherd dogs should be applied.