Until recently, bluetongue (BT) virus (BTV) serotypes reportedly causing transplacental infections were all ascribed to the use of modified live virus strains. During the 2007 BT epidemic in Belgium, a significant increase in the incidence of abortions was reported. A study including 1348 foetuses, newborns and young animals with or without suspicion of BTV infection, was conducted to investigate the occurrence of natural transplacental infection caused by wild-type BTV-8 and to check the immunocompetence of newborns. BTV RNA was present in 41% and 18.5% of aborted foetuses from dams with or without suspected BTV involvement during pregnancy, respectively. The results of dam/calf pairs sampled before colostrum uptake provide evidence of almost 10% transplacental BTV infection in newborns. Apparently immunotolerant calves were found at a level of 2.4%. The current study concludes that the combined serological and real-time PCR (RT-qPCR) result of pregnant dams gives no indication of the infection status of the offspring except in the case of a double negative result. In a group of 109 calves with clinical suspicion of BT, born during the vector-free period, 11% were found to be RT-qPCR positive. The true prevalence was estimated to be 2.3%, indicating the extent of transplacental infection in a group of 733 calves of one to 4 months of age without BT suspicion. Moreover, virus isolation was successful for two newborn calves, emphasizing the need for restricting trade to BT-free regions of pregnant dams possibly infected during gestation, even if they are BTV RT-qPCR negative.

The metabolic status of normal lactating cows and of cows suffering from abomasal dilatation was evaluated by examination of blood parameters and by determination of the fat and glycogen content in liver biopsies. The method for examination of the liver biopsies is described.In clinically normal lactating cows the liver contains less than 20 mg triglycerides (TG) and more than 20 mg glycogen per gram of wet tissue. Cows suffering from abomasal displacement all showed hyperglycemia and in most of them a fatty to very fatty liver was found.The degree of hyperglycemia depends on the amount of liver glycogen and is independent of the liver TG content. The degree of ketonemia also depends on the liver glycogen content.

No abstract

No abstract

No abstract