Serum alpha1-proteinase inhibitor concentrations in dogs with systemic inflammatory response syndrome or sepsis

Objective - To determine whether the concentration of serum canine alpha(1)-proteinase inhibitor (c alpha(1)-PI) has diagnostic or prognostic utility in dogs with sepsis or noninfectious systemic inflammatory response syndrome (SIRS). Design - Prospective, observational study from May to December 2010. Setting - University teaching hospital ICU. Animals - Sixty-nine client-owned dogs: 19 dogs with SIRS or sepsis and 50 healthy control dogs. Interventions - None. Measurements and Main Results - Serum and plasma samples were collected from dogs with SIRS or sepsis on the day of hospital admission and once on the following 2 days, and on a single day in healthy controls. Patients were assessed using the 10-parameter Acute Patient Physiologic and Laboratory Evaluation (APPLE(full)) and 5-parameter (APPLEfast) score. Serum c alpha(1)-PI concentrations were measured, compared among groups of dogs, and evaluated for a correlation with the concentration of serum C-reactive protein, plasma interleukin-6, tumor necrosis factor-alpha, the APPLE scores, and survival to discharge. Serum c alpha(1)-PI concentrations were significantly lower in dogs with SIRS/sepsis (P < 0.001) than in healthy controls. While day 1 serum c alpha(1)-PI concentrations did not differ between dogs with SIRS and those with sepsis (P = 0.592), septic dogs had significantly lower serum c alpha(1)-PI concentrations on days 2 (P = 0.017) and 3 (P = 0.036) than dogs with SIRS. Serum c alpha(1)- PI concentrations did not differ between survivors and nonsurvivors (P = 1.000), but were inversely correlated with the APPLE(full) score (rho =-0.48; P= 0.040) and plasma interleukin-6 concentrations(alpha = -0.50; P = 0.037). Conclusions - These results suggest a role of c alpha(1)-PI as a negative acute phase protein in dogs. The concentration of serum c alpha(1)-PI at the time of hospital admission does not have utility to identify dogs with sepsis from those with noninfectious SIRS, but may be a useful surrogate marker for early stratification of illness severity.