Leptosporosis remains a serious cause of abortions in breeding herds. Lepto is caused by a bacteria, which is shed in urine and transmits by splashing into the mucous membranes of the eyes and mouths of cattle. It's particularly common in humid areas or areas where there is standing water. There are many strains of lepto including the most common, known as Hardjo. The venereal disease spreads through breeding and occasionally causes abortions.
Some researchers consider it to be the leading cause of infertility in cattle.
Animal health companies market combination products that include IBR, BVD, lepto and vibrio vaccines. The key is to give these vaccines to cows and heifers before the breeding season. Neosporosis is a recently discovered cause of abortions in cows. The disease has been diagnosed in most states, usually in dairy cows. Neosporosis was first diagnosed in California dairies.