Sepsis and survival in critically ill calves: Risk factors and antimicrobial use

BACKGROUND: Sepsis is a life‐threatening disease for which critically important antimicrobials (CIA) frequently are used. Diagnostic and therapeutic guidelines for sepsis and critically ill calves are largely lacking. OBJECTIVES: Identify factors associated with mortality in critically ill calves and describe bacteria obtained from blood cultures of critically ill calves with sepsis and their antimicrobial resistance. ANIMALS: Two‐hundred thirty critically ill calves, mainly Belgian Blue beef cattle. METHODS: Retrospective cohort study. Logistic regression, survival analysis, and decision tree analysis were used to determine factors associated with mortality. RESULTS: Of the critically ill calves, 34.3% had sepsis and 61.3% died. The final survival model indicated that calves with sepsis (hazard risk [HR]: 1.6; 95% confidence interval [CI]: 1.0‐2.5; P = .05), abnormal behavior (HR: 2.3; 95% CI: 1.3‐4.0; P = .005), and hypothermia (HR: 0.82; 95% CI: 0.72‐0.95; P = .01) had a significantly higher mortality risk. In a second survival model, hypothermia (HR: 0.87; 95% CI: 0.78‐0.96; P = .004) and hypoglycemia (HR: 2.2; 95% CI: 1.5‐3.3; P < .001) were risk factors for mortality. Decision tree analysis emphasized the importance of behavior, hypochloremia, hypoglycemia, hyperkalemia, and lung ultrasonography for mortality risk. Escherichia coli (30.6%) was most frequently isolated from blood cultures, of which 90.9% were multidrug resistant. Inappropriate use of antimicrobials was frequent for penicillin, amoxicillin, and sulfamethoxazole/trimethoprim, but less for CIA. CONCLUSIONS AND CLINICAL IMPORTANCE: Many critically ill calves have sepsis, which increases mortality risk. Bacteria involved are often resistant to first‐intention antimicrobials but less resistant to CIA. The other identified risk factors for mortality can support therapeutic decision‐making.