Porcine Parvovirus infection: review and diagnosis in a sow herd with reproductive failure

In a commercial swine herd a rise was noted during the summer of 1981 in the number of repeat breeders, mostly four to eight weeks after serving. During the autumn there was a decrease in the litter size at birth and an increase in the number of stillborn and mummified piglets. Several gilts and sows showed a seroconversion against Porcine Parvovirus (PPV), determined by the Haemagglutination Inhibition test (HI-test). Characteristic pathological findings were seen in some maturely stillborn and neonatally decreased piglets (up to an age of 28 days); hepatic congestion and necrosis, accummulation of fluid in body cavities, myocarditis, and encephalitis were the most prominent features. Serological tests for antibodies in blood samples of one sow and body fluids of two stillborn piglets were suggestive of Porcine Parvovirus as the aetiological agent.     

La vascularisation du feuillet du boeuf)

The blood vascular system of the bovine omasum The blood vessels supplying and draining the omasal wall and laminae are described and are compared with those of other ruminants. A detailed study revealed that the subepithelial vascular networks in the papillae were in part similar to those of intestinal villi. One or more arterioles branch radially and form a capillary network which does not, as in the villus, drain into a central venule but is succeeded by several subepithelial venules. Capillaries and venules differ only in diameter which are 10 μm. and 40 μm. respectively. The walls of both have a complete basal membrane, perforated endothelium and pinocytotic vesicles. This emphasizes their significance in resorption. Inside and between the papillae the capillaries form a dense network which is separated from the basal cells by a thin layer of connective tissue 5 to 6 μm. thick. Hemodynamic problems related to the presence of elastic connective tissue and to the motor activity of the omasum are discussed.     

Repair of a salivary duct fistula in a horse without using a stent

A salivary duct fistula in a horse was repaired surgically without using a stent. Seventeen months after the operation the skin incision had healed without complications and the fistula had not recurred.     

Susceptibility of sheep to European bat lyssavirus type-1 and -2 infection: a clinical pathogenesis study

European bat lyssaviruses (EBLVs) have been known to cross the species barrier from their native bat host to other terrestrial mammals. In this study, we have confirmed EBLV-1 and EBLV-2 susceptibility in sheep (Ovis ammon) following intracranial and peripheral (intramuscular) inoculation. Notably, mild clinical disease was observed in those exposed to virus via the intramuscular route. Following the intramuscular challenge, 75% of the animals infected with EBLV-1 and 100% of those that were challenged with EBLV-2 developed clinical signs of rabies and then recovered during the 94-day observation period. Disease pathogenesis also varied substantially between the two viruses. Infection with EBLV-1 resulted in peracute clinical signs, which are suggestive of motor neuron involvement. Antibody induction was observed and substantial inflammatrory infiltrate in the brain. In contrast, more antigen was detected in the EBLV-2-infected sheep brains but less inflammatory infiltrate and no virus neutralising antibody was evident. The latter involved a more protracted disease that was behaviour orientated. A high infectious dose was required to establish EBLV infection under experimental conditions (> or =5.0 logs/ml) but the infectious dose in field cases remains unknown. These data confirm that sheep are susceptible to infection with EBLV but that there is variability in pathogenesis including neuroinvasiveness that varies with the route of infection. This study suggests that inter-species animal-to-animal transmission of a bat variant of rabies virus to a terrestrial mammal host may be limited, and may not always result in fatal encephalitis.     

Simulation evaluation of Salmonella monitoring in finishing pigs in Lower Saxony, Germany

Results of serological monitoring for Salmonella in finishing pigs are used to classify herds and target control measures at herds with high prevalence. The outcome of monitoring is determined by three factors: (a) the cut-off value for the optical density percentage (OD%) to declare a sample positive, (b) the classification scheme to allocate farms to different Salmonella prevalence classes, and (c) the annual number of samples per herd to calculate its Salmonella prevalence. Our goal was to analyse the impact of these three factors on (i) the accuracy of Salmonella monitoring in finishing pigs and (ii) the total number of tests required. We constructed a stochastic simulation model in Excel and @Risk to evaluate 12 monitoring scenarios based on: (a) four cut-off values for the OD% (10, 20, 30, and 40) and (b) three herd classification schemes. Furthermore, eight different sampling schemes were evaluated. The main outputs of the model are (a) the accuracy of monitoring which is reflected by the percentage of herds that retain classification when re-sampled at the same moment in time and (b) the total number of tests. To illustrate the model, we used input data from Salmonella monitoring in Lower Saxony, Germany. Model calculations demonstrated that - with the tests in use - monitoring scenarios based on cut-off OD% 10 are most accurate with 80-90% of herds retaining classification. Monitoring scenarios based on cut-off OD% 20 or 30 are, however, comparable to those based on cut-off OD% 40 with 50-70% of herds retaining classification. Besides, we predicted that herd classifications based on three classes (low-, moderate-, and high-prevalence) give more accurate results than when a zero-prevalence class is included. The total number of tests depends heavily on the sampling scheme and - if sampling is based on Salmonella prevalence class - the distribution of herds over the different classes. We predicted that the current German sampling scheme that is based on herd size requires more tests than those sampling schemes based on herd classification. Of these, the sampling scheme in which most samples are taken from high-prevalence herds is most accurate and might be a good incentive to reduce Salmonella prevalence at herd level if farmers had to pay for the tests themselves.     

Genetic differences in water-use efficiency,stomatal conductance and carbon isotope fractionation in potato

Summary Potato (Solanum tuberosum L.) cultivars were grown in pots and containers under a rain shelter to examine differences in stomatal conductance, water-use efficiency, and carbon isotope fractionation. Conductance was measured on abaxial leaf surfaces with a steady state diffusion porometer. Carbon isotopic analyses were made with an isotope ratio mass spectrometer. Water-use efficiency (WUE) was obtained by dividing total dry matter production by cumulative transpiration. Significant genetic variation was observed for each trait. WUE was positively related to carbon isotope fractionation (¹³∈) and was inversely related to stomatal conductance. Carbon isotope analysis and porometry show potential as indirect screening methods to identify genetic differences in water-use efficiency.