Bacterial endometritis and vaginal discharge in the sow: prevalence of different bacterial species and experimental reproduction of the syndrome

A total of 73 porcine genital tracts were macroscopically and histologically examined and bacteriologically tested for the presence of aerobic facultatively pathogenic bacteria. Nine uteri originated from sows with abnormal vaginal discharge (P-group) and 64 uteri originated from slaughtered sows (S-group). Fifty-six per cent of the uteri from the P-group were bacteriologically positive compared with only 20% of the uteri from the S-group. Uteri of sows with histological evidence of an acute or subacute endometritis were significantly more often infected than the uteri of sows with a chronic endometritis or with histologically normal uteri. The bacteria isolated were mainly Escherichia coli, Staphylococcus spp. and Streptococcus spp. These results indicate that the syndrome of endometritis and vaginal discharge is possibly caused by ascending infections with facultatively pathogenic bacteria. luate the pathogenicity of the isolated bacteria, experimental infections were carried out. Ten pubertal, unmated gilts were inoculated in the uterus by laparotomy with 2 ml of a suspension containing Staphylococcus hyicus, an E. coli sp., an Actinomyces sp. or a carboxyphilic Streptococcus suis sp. An eleventh gilt was inoculated as a control with 2 ml of a phosphate-buffered saline (PBS) solution. The gilts were daily observed for clinical symptoms. Ten to 19 days after inoculation a second laparotomy was carried out to take samples for histological and bacteriological examination. Vaginal discharge was observed in all gilts inoculated with E. coli 109 cfu ml−1 or S. hyicus. Clinical signs were not observed in the gilts that were inoculated with the Actinomyces sp., the carboxyphilic Streptococcus suis sp. or 107 cfu E. coli. It was possible to reproduce the syndrome of vaginal discharge as it occurs on problem herds, by means of an experimental infection with an E. coli or Staphylococcus hyicus strain. According to Kochʹs postulates, both inoculated bacteria can be considered as an aetiologic agent of the disease.