Bovine virus diarrhoea virus, a cause of early pregnancy failure in the cow.

In the present report attention is drawn to clinical and hormonal changes in heifers following experimental or natural infection with bovine virus diarrhoea virus in early pregnancy. Three heifers were infected experimentally and one naturally at pregnancy stages from 29-41 days. A leukopenia was seen 5-7 days after infection. All four animals experienced foetal death. Two of them aborted and in two the foetus was resorbed. Oestrus was observed at the expulsion of the foetus or in connection with vaginal discharge. Peripheral blood plasma levels of progesterone and the main blood plasma metabolite of prostaglandin F2 alpha (15-keto-13,14-dihydro-PGF2 alpha) were analysed. Diagnosis of pregnancy and embryonic/foetal viability were monitored by ultrasound. The interrelationship between infection and reproductive endocrinology is discussed and the importance of avoiding infection in early gestation is pointed out. It may easily pass unobserved and can thereby cause serious economic loss.