Symmetric and asymmetric dimethylarginines in healthy and colic horses

This study investigated the plasma concentrations of symmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA) in healthy horses and in horses affected by colic in relation to the type of colic and systemic inflammation response syndrome (SIRS) status. Upon admission (T0), horses underwent a physical examination, and the SIRS status was assessed. The horses with colic were divided retrospectively based on the type of colic, SIRS status, treatment, and outcome. SDMA and ADMA levels were measured at T0 and then every 24 h at four time points (T1, T2, T3, T4). Differences between groups (healthy, non-strangulating intestinal obstruction, strangulating intestinal obstruction, SIRS-positive, and SIRS-negative) were analysed with the Kruskal-Wallis test. Changes within groups over time were assessed using Friedman's two-way analysis of variance by ranks. Generalized linear mixed models (GLMMs) were used to analyze SDMA and ADMA levels in colic horses. Diagnostic accuracy was assessed using receiver operating characteristic curves, cut-off values, area under the curve analysis, and 95 % confidence intervals. SDMA concentrations were significantly lower in healthy horses compared to colic patients across all sampling times. ADMA levels were significantly higher at T2 in strangulating colic and SIRS-positive horses compared to healthy horses. GLMM analysis revealed no differences in SDMA or ADMA concentrations based on colic type, SIRS status, treatment, or outcome. Neither SDMA nor ADMA appeared to offer clinical utility as biomarkers in distinguishing between strangulating and non-strangulating colic or SIRS-positive and negative horses.