A complex malformation in a pig: case report and review of the literature

Congenital defects like myofibrillar dysplasia (splayleg), umbilical and inguinal hernias, cryptorchism, intersexes, and anal atresia occur relatively frequently in swine. On the other hand, some developmental anomalies like double monsters are very rare. The present paper reports a rare case of a congenital complex malformation including polymelia, duplicitas coli partialis et recti, atresia ani et fistula rectogenitalis, duplicitas corpori uteri, cervicis, vaginae et vulvae and duplicitas vesicae, urethrae et renalis. A plausible interpretation concerning the etiology is that the anomalies arose from unequal partial twinning. The pig has been healthy and inconspicuous. Although no anus was formed defecation took place via a fistula to one of the vaginas. Posture and behaviour of the pig were normal. Cytogenetic analysis of blood lymphocytes revealed no numerical or gross structural anomalies. There have been no further piglets with developmental disorders in the same litter, in a second litter of the same parents and in other twelve litters by the same boar.     

Genetics and disease resistance

Genetic components of disease resistance have been described in most of important diseases in human as well as in laboratory and livestock animals. However the basic mechanisms have been established in a few examples only. The reasons herefore are the mostly polygenic inheritance of disease resistance traits, the missing of suitable animal models and the dominance of environmental effects like infection pressure, immune status, and stressors, limiting the view on responsible gene variants. Ethical and practical aspects may further hinder research on disease resistance in certain species. Livestock animals play a crucial role in disease resistance research, because of distinct genetic diversity within and between breeds, because of an often distinct metabolic congruency with humans, and aiming towards the improvement of hygiene and economy of production and animal welfare. The following sections will review disease resistance in livestock animals and their practical implications, completed by examples of our own research activities.     

Analysis of bacterial load and prevalence of mixed infections with Lawsonia intracellularis, Brachyspira hyodysenteriae and/or Brachyspira pilosicoli in German pigs with diarrhoea

Lawsonia (L.) intracellularis, Brachyspira (B.) hyodysenteriae and B. pilosicoli are important pathogens in domestic pig production world-wide, responsible for porcine intestinal adenomatosis, swine dysentery, and porcine intestinal spirochetosis, respectively. Conventional PCR is the major diagnostic tool in the detection of the three pathogens, but the sole detection of bacterial DNA might lead to misinterpretations of results with respect to their clinical relevance, especially with mixed infections. Thus, the present study targeted the detection and quantification of the three pathogens in samples from herds with a case history of diarrhoea. Herds and samples were selected by the practitioners on a voluntary basis. Results were based on 1176 individual samples from 95 herds from Southern Germany. The pathogens were detected simultaneously by multiplex real-time PCR. The overall prevalence for L. intracellularis, B. hyodysenteriae and B. pilosicoli was 12.6%, 8.4% and 3.2% in faecal samples and 48.4%, 24.2% and 31.6% in herds, respectively. Sixty one percent, 82.6%, and 73.4% of herds positive for L. intracellularis, B. hyodysenteriae, and B. pilosicoli, respectively, had mixed infections. Median log values of DNA equivalents/g of faeces for L. intracellularis, B. hyodysenteriae and B. pilosicoli were 3.3, 5.9 and 3.2, with maxima of 8.3, 8.0 and 6.3, respectively. Within herd prevalence of B. hyodysenteriae and B. pilosicoli as well as the load of B. hyodysenteriae were significantly associated with the severity of diarrhoea.     

Interferon-gamma response of PBMC indicates productive pseudorabies virus (PRV) infection in swine

In Chinese Meishan/German Landrace cross-bred swine F2 generation interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) was determined directly ex vivo at different time points after survival of a virulent pseudorabies virus (PRV) infection. This reactivity was compared with the reactivity of na?ve PBMC. Significant IFN-gamma production was determined in ELISA and ELISPOT only after in vitro PBMC re-stimulation with PRV and not with the closely related bovine herpesvirus BHV-1. The PRV-specific IFN-gamma secretion from re-stimulated PBMC showed high levels 6 days after infection, before the presence of serum antibodies, and it persisted at a high level over a 3 months period. The response of a group of eight piglets infected intranasally with PRV varied. Only two animals showed the expected typical fever response. PRV specific IFN-gamma production by PBMC clearly indicated that infection had occurred. Early significant IFN-gamma production by primed PBMC turned out to be a reliable and specific ex vivo marker for cellular response against productive PRV infection in swine before antibody formation.     

Report on Salmonella isolates submitted to the German National Veterinary Salmonella Reference Laboratory in the year 1999

The National Salmonella Reference Laboratory (NRL-Salm) of the Federal Institute for Health Protection of Consumers and Veterinary Medicine receives putative Salmonella isolates originating from animals, food, feed and the environment for typing. This report summarises the results of the sero- and phagetyping studies. In livestock S. Typhimurium DT 104 with 24% and S. Enteritidis PT 4 with 9% of all isolations predominate like in the human isolates. These sero- and phagetypes are frequently isolated from food as well and consequently can reach the consumer via the food chain.     

Variation in resistance to the Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in Pietrain and Miniature pigs

Porcine reproductive and respiratory syndrome (PRRS) is one of the economically most important diseases of swine. Viraemia and the prolonged persistence of the virus are among the most critical factors. Virus replication and severity of disease vary with virus isolates, and there is rising evidence for a genetic component of the host susceptibility. Dissecting the genetic basis of resistance/susceptibility to PRRS virus (PRRSV) might lead to improved knowledge on the molecular mechanisms of PRRS and the establishment of genetic markers for future disease control. The aim of this study was to establish a porcine model with emphasized genetic differences in PRRSV susceptibility. Seven ‘Wiesenauer Miniature’ pigs (MI), a local German breed and eight commercial Pietrain (PI) pigs were challenged with 10⁵ TCID₅₀ of an attenuated PRRSV strain (Ingelvac^® PRRSV MLV). Clinical status, viraemia and seroconversion of the pigs were compared. No clinical signs were observed during the experiment. Viraemia peaked on day 6 p.i., with 100% of viraemic pigs in PI and on day 12 p.i with 87% of viraemic MI. Viraemia lasted for up to 35 days in MI and for at least 72 days in PI. This surprising result was confirmed by a second study with another four MI. MI and PI showed maximum virus titres of 10^2.5 TCID₅₀/ml of serum and 10^4.5 TCID₅₀/ml, respectively, indicating a virus replication in MI of approximately 3.3% that of PI over the complete period. MI were more efficient in antibody production. With such pronounced breed differences, the model is of high relevance for the genetic dissection of PRRS pathogenesis and susceptibility.