Determining prognosis in canine sepsis by bedside measurement of cell-free DNA and nucleosomes.

OBJECTIVE: To investigate the use of plasma cell-free DNA (cfDNA) and nucleosome concentrations as prognostic biomarkers in canine sepsis.

DESIGN: Prospective, observational cohort study conducted from June 2015 to February 2016.

SETTING: University teaching hospital.

ANIMALS: Forty-five dogs with sepsis, 10 dogs with nonseptic systemic inflammatory response syndrome (nSIRS), and 15 healthy controls were consecutively enrolled and followed to hospital discharge. Patients were eligible for enrollment if they met ≥2 SIRS criteria and had a documented or highly suspected bacterial infection. Dogs <3 kg or with a known coagulopathy were excluded.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Acute Patient Physiology and Laboratory Evaluation scores (APPLE) were calculated and outcomes recorded. Plasma cfDNA was measured using a benchtop fluorimeter. Plasma nucleosome concentrations were determined by ELISA. Plasma nucleosome and cfDNA concentrations in dogs with sepsis or nSIRS were compared to those of healthy controls and cfDNA concentrations in septic dogs with and without bacteremia were compared. Associations between cfDNA concentrations and nucleosomes, leukocyte count, neutrophil count, and APPLE scores were evaluated. For septic dogs, cfDNA concentrations relative to neutrophil count and nucleosome concentrations in survivors and nonsurvivors were compared. Alpha was set at 0.05. cfDNA concentrations were significantly higher in dogs with sepsis or nSIRS compared to healthy controls (P < 0.0001 and P = 0.0034, respectively). Nucleosome concentrations were significantly higher in dogs with sepsis compared to healthy controls (P = 0.007). There was limited association between cfDNA and nucleosome concentrations (rs  = 0.266), and no association between cfDNA concentration and leukocyte count, neutrophil count, and APPLEfull scores. Concentrations of cfDNA were positively correlated with APPLEfast score (rs  = 0.335, P = 0.025); however, cfDNA concentrations were significantly higher in dogs with bacteremia (P = 0.0299). In dogs with sepsis, cfDNA concentrations relative to neutrophil count were significantly higher in nonsurvivors than in survivors (P = 0.008).

CONCLUSIONS: In dogs with sepsis, high cfDNA concentrations relative to neutrophil count are associated with nonsurvival. Point-of-care cfDNA measurement may aid identification of bacteremia.