Comparative Analysis of Haematological and Biochemical Responses to Haemorrhagic Septicaemia in Naturally Infected and Vaccinated Cattle in Kebbi State, North West Nigeria

Haemorrhagic septicaemia caused by Pasteurella multocida serotypes B and E remains a devastating disease of cattle in sub-Saharan Africa, and the comparative biochemical responses between vaccinated and unvaccinated animals during natural outbreaks provide critical insights for vaccine programme evaluation. This study conducted a comparative analysis of haematological and biochemical responses in naturally Pasteurella-infected vaccinated and unvaccinated Bunaji cattle during an outbreak in Kebbi State, North West Nigeria. Forty vaccinated and forty unvaccinated Zebu cattle from affected farms were enrolled at the onset of clinical signs. Complete blood count, serum fibrinogen, haptoglobin, albumin, gamma-globulin, interleukin-6, and tumour necrosis factor-alpha were measured at days zero, three, and seven of the outbreak. Unvaccinated cattle demonstrated significantly higher fibrinogen, haptoglobin, and inflammatory cytokine concentrations throughout the monitoring period, with mortality concentrated in this group. Vaccinated cattle showed attenuated acute-phase responses with faster biochemical normalisation, despite similar initial clinical presentations. Gamma-globulin was significantly higher in vaccinated survivors, confirming humoral immunological protection. Fatality rate was 55% in unvaccinated versus 12.5% in vaccinated cattle. These findings provide an empirical biochemical basis for haemorrhagic septicaemia vaccine programme justification in North West Nigeria and highlight the importance of acute-phase protein assessment in outbreak response characterisation. Keywords: haemorrhagic septicaemia, acute-phase proteins, vaccination, cattle, Kebbi State.