Virulence comparison and quantification of horizontal bovine viral diarrhoea virus transmission following experimental infection in calves.

Bovine viral diarrhoea virus (BVDV) causes persistent infections by infecting the fetus of susceptible animals during gestation. These persistently infected (PI) animals are important sources of infection. On the contrary, transiently infected (TI) animals are believed to be less important, but transient infections with a severe BVDV-2 strain can spread explosively. To assess the importance of TI cattle in the epidemiology of BVDV, two experimental infections were performed to determine basic reproduction ratios (R0). In each experiment three calves were infected via intranasal inoculation and housed together with seven susceptible animals. Two strains isolated in Belgium were used, a virulent BVDV-1b and a virulent BVDV-2a field isolate, resulting in an R0 of 0.25 (95% CI 0.01; 1.95) and 0.24 (95% CI 0.01; 2.11), respectively. A PI animal was then introduced to the remaining uninfected animals and produced an R of +∞ (95% CI 1.88; +∞). These results support the suggestion that TI animals, compared to PI animals, contribute only a limited amount to BVDV spread. Additionally, the severe clinical symptoms observed in the field with these isolates could not be reproduced during these experiments, suggesting that other factors besides strain virulence influence the clinical manifestations evoked by BVDV.

Protocol of the Caesarean section as performed in daily bovine practice in Belgium.

In the early part of the 20th century, veterinarians began to perform Caesarean section (CS) in cows. At first, it was a final remedy to save the calf and/or the cow in more complicated obstetrical cases. As in Belgium, the Belgian Blue (BB) breed has become the predominant beef breed, CS are currently performed on a routine basis in daily practice. The overwhelming success of the breed is based on its hypermuscularity and exceptional carcass characteristics with high killing out (>70%). These and other characteristics made the breed popular and newborn animals valuable. Consequently, farmers do not want to take any risk of losing the calf during birth. This, together with the fact that bovine practitioners perform CS successfully on a routine basis, has made CS an elective operation. It is, however, important to remember that CS is still a major abdominal operation and that complications are not uncommon both during and after the operation. To end up with a good success rate, it is very important to follow a high-quality and sterile surgical procedure. The current paper describes the standard protocol by which CS are performed by the veterinarians of the Ambulatory Clinic of the Department of Reproduction, Obstetrics, and Herd Health of the Faculty of Veterinary Medicine in Ghent (Belgium). The aim of the article is to provide a successful protocol as regards CS. We especially focus on those factors which are known to be limiting for the success of the surgery and highlight the most recent recommendations to optimize the outcome of the operation.

Differential diagnosis of neurologically expressed disorders in Western European cattle.

A classification of neurological or neurologically expressed disorders that occur in Western European cattle aged 12 month and over has been established on the basis of aetiology, frequency and conditions of appearance, age and type of animals concerned and the main clinical signs observed. Neurologically expressed disorders have been classified according to different groups of causes: biological, non-biological and non-specific or unknown. Differential diagnosis of neurologically expressed disorders is an essential element in the clinical epidemiological surveillance of bovine spongiform encephalopathy. A growing number of aetiologies are described in the scientific literature. The identification and centralised management of neurological disorders will make it possible, one the one hand, to take account of the inherent variability in the clinical forms encountered and in the diagnostic approaches of the observers and, on the other hand, to identify new risk factors in order to control them.