Pathology and pcr based confirmation of haemorrhagic septicemia outbreaks in bovines

Two large outbreaks ofhaemorrhagic septicemia were recorded in Punjab, India in the unvaccinated herds with high cumulative incidence (0.44), cumulative mortality (0.17) and case fatality rate (0.39). Typical clinical symptoms of swelling of neck and throat region were absent and confirmation of the disease could be made on the basis of postmortem lesions, mice inoculation and molecular characterization of the isolated organism. Gross post mortem lesions were fibrinous deposits, marbling and adhesions of lungs to rib case; lungs were severely consolidated giving it liver like consistency. All visceral organs exhibited petechial to ecchymotic haemorrhages on the serosal surfaces. In some animals, hydrothorax, pleurisy and hydropericardium were also prominent. Histopathologically, septae were thickened due to oedema giving marbling pattern to lungs. The pure colonies isolated on blood agar showed typical biochemical characteristics of Pasteurella multocida. The heart blood inoculated intraperitoneally into mice caused mortality within 24 hours indicating strain to be highly pathogenic. The bipolar organisms were again isolated and demonstrated from the heart blood of mice. The organisms were characterized by PCR using P multocida B: 2 specific primers showing two bands corresponding to approx. 460 bp and 590 bp. The isolates were sensitive to enrofloxacin, gentamicin, erythromycin, cephotaxime, cephalexin, pefloxacin and chloromphenicol but resistant to streptomycin and oxytetracycline.