Salivary alpha-amylase activity and concentration in horses with acute abdominal disease: Association with outcome

Abstract

Background: Salivary biomarkers could be useful to objectively evaluate critical illness and prognosis for survival in horses with acute abdominal disease. Objectives: To compare salivary alpha-amylase (sAA) activity and concentration in healthy horses and horses with acute abdominal disease, and evaluate the association between sAA activity and concentration with disease severity and outcome. Study design: A prospective cohort. Methods: sAA activity, measured using a colorimetric commercial kit, and concentration, measured using a Time-resolved immunofluorometric assay, in 25 healthy horses and in 33 horses with acute abdominal disease was compared using an ANOVA. Associations between survival to discharge and sAA activity and concentration and other clinical parameters were examined using univariable logistic regression and Spearman correlation. Results: sAA activity and concentration were different between healthy (median = 4.3 [2.6–11.2] IU/L and 58.4 [53.4–80.6] ng/mL, respectively) and diseased (median = 29.8 [14.2–168.9] IU/L and 388.3 [189.1–675.8] ng/mL, respectively) (P<0.001). The sAA activity was higher in non-survivors (median = 479.0 [78.7–2064.0] IU/L, n = 8) compared to survivors (median = 19.3 [12.1–103.7] IU/L, n = 25, P<0.001) and sAA activity and concentration correlated (P<0.001) moderately with HR (r = 0.66 and r = 0.61, respectively). sAA activity correlated weakly with salivary cortisol (r = 0.45, P<0.001) and systemic inflammatory response syndrome score (r = 0.43, P<0.05), while activity and concentration correlated (P<0.001) moderately with plasma lactate concentration (r = 0.57 and r = 0.60, respectively). The sAA activity was significantly (P = 0.01) associated with increased risk of nonsurvival. Main limitations: Pain scores were not recorded. The sample population was small. Conclusions: The sAA activity, but not concentration, shows potential as a biomarker of prognosis for survival in horses with acute abdominal disease.