A survey is given of the occurrence of mycotic infections associated with abortion in Danish cattle. During a period of six years a total of 748 samples of placenta material were examined. Mycotic abortion was demonstrated in 101 cases (14%). The case rate was significantly higher (21%) during the winter months from December through February than during the rest of the year (10%). Abortions occurred as from the 135th day of pregnancy, with maximum in the eighth month, where 45% of all cases were observed. A. fumigatus was demonstrated in 77 cases, Mucor spp. in 11 cases, Absidia spp. in 5 cases, and a mixed infection with A. fumigatus and Mucor spp. in 3 cases. In 5 cases the fungi were demonstrated by microscopic and histological examination, but not by culture. The annual occurrence of mycotic abortion varied from 10% to 24% of cases of abortion examined. The latter figure was recorded in a year following a particularly heavy rainfall in the month of June.
