Intestinal pathogens, diarrhoea and acute phase proteins in naturally infected dairy calves

• Multiple intestinal pathogen species were present in both healthy and diarrheic calves.
• Decreased haptoglobin concentrations were associated with weak signs of eimeriosis.
• Increased haptoglobin and fibrinogen concentrations were associated with respiratory tract infection and umbilical infection.

In this study, the association between Eimeria spp. related signs and innate immune response in dairy calves was examined. Calves (n = 100) aged 15–60 days were clinically examined and faecal samples, blood samples and deep nasopharyngeal swabs obtained. The samples were analysed for intestinal pathogens, acute phase proteins and WBC count, and respiratory tract pathogens, respectively.Diarrhoea was diagnosed in 32.6% (23.3–43.0%, 95% CI) of calves. An association between the pathogenic Eimeria spp. and diarrhoea was detected by multiple correspondence analysis. Eimeria related signs (diarrhoea, presence of pathogenic species and total oocyst count) were combined resulting a four level variable. Calves with weak signs of eimeriosis had decreased haptoglobin concentrations (p = 0.02) and increased fibrinogen concentrations (p = 0.048) compared to no signs. Increased haptoglobin and fibrinogen concentrations were associated with respiratory tract infection and umbilical infection. Serum amyloid A and WBC counts showed no association with signs of eimeriosis or clinical diagnoses.