Sepsis in small animals: from the diagnosis to the antimicrobial stewardship programs

Sepsis is a life-threatening condition with high morbidity and mortality in both humans and animals. Early recognition is critical to enable timely treatment, which significantly affects outcomes. In veterinary medicine, sepsis diagnosis remains challenging due to limitations in clinical and laboratory tools. Concurrently, inappropriate antimicrobial use drives the emergence of multidrug-resistant (MDR) bacteria, emphasizing the need for antimicrobial stewardship (AMS). This study aimed to: evaluate novel clinical and laboratory biomarkers for the diagnosis, severity assessment, and outcome prediction of sepsis in critically ill dogs and cats; and investigate antimicrobial use in veterinary intensive care to support the development of an AMS program in a university hospital setting. Critically ill dogs and cats admitted to the Veterinary University Hospital of Bologna were included. Diagnostic studies evaluated apolipoprotein A1 (Apo-A1), serum amyloid A, new-onset organ dysfunction, and triage body temperature. Antimicrobial use was assessed through a four-year surveillance of bloodstream infections and a preliminary analysis of prescribing patterns in the ICU, compared with practices in a Dutch veterinary teaching hospital. Apo-A1 was a useful biomarker for sepsis severity in dogs but did not predict outcomes. New-onset organ dysfunction was not diagnostic for sepsis but the presence of multiple organ dysfunctions was associated with mortality. In cats, hypothermia at triage was frequent and significantly associated with non-survival, particularly in septic patients. Bloodstream infection surveillance revealed 29% MDR isolates, often linked to healthcare-associated infections and invasive devices. Antimicrobial use analysis showed frequent empirical use of broad-spectrum drugs, limited de-escalation, and higher fluoroquinolone use in Bologna compared with Utrecht. This thesis provides insights into biomarkers of sepsis severity in dogs and cats and identifies critical issues in antimicrobial prescribing in veterinary ICUs. Findings support the implementation of diagnostic and stewardship strategies to improve patient outcomes and mitigate antimicrobial resistance in veterinary hospitals.