Characterizing bacteremia in neonatal calves with diarrhea: a case-control study

BACKGROUND: Detecting bacteremia in calves is essential to identify those calves with systemic infections that could benefit from antimicrobial therapy. HYPOTHESIS/OBJECTIVES: To determine the prevalence of bacteremia in neonatal calves with diarrhea in a commercial setting and investigate the association between clinical and blood variables with bacteremia. ANIMALS: One hundred neonatal calves with diarrhea. METHODS: Case-control study. Clinical and laboratory variables were analyzed using exact conditional logistic regression and classification analysis and regression tree (CART) to evaluate their association with bacteremia, which was determined by blood culture. RESULTS: The prevalence of bacteremia was 37% (37/100). The most frequently identified bacteria were Streptococcus ruminantium and Escherichia coli. In the multivariable model including all the clinical and laboratory variables, HCO3- (for each 1 mmol/L increase odd ratio [OR]: 0.78; 95% CI, 0.60-0.95 mmol/L) and albumin concentration (for each 1 g/dL increase OR: 0.67; 0.43-0.93 g/dL) were associated with lower odds of bacteremia on the first day it was detected, whereas the presence of scleral injection was associated with increased odds of bacteremia (OR: 10.75; 95% CI, 11.11-inf.). The CART indicated that low heart rate (< 98 beats per minute), enophthalmos (> 2.5 mm), lower monocyte count (< 0.63 x 109/L) and red cell distribution width (< 23%) were important predictors of bacteremia in diarrheic neonatal calves. CONCLUSIONS AND CLINICAL IMPORTANCE: Scleral injection, greater rectal temperature, enophthalmos, electrolyte derangement, and lower RDW and albumin concentration could be used to identify bacteremia in diarrheic neonatal calves.