Hyponatremia in horses with septic pneumopathy.

Abstract

BACKGROUND: Hyponatremia is common in horses with bacterial pleuropneumonia, but no further characterization of this abnormality has been reported. OBJECTIVES: Describe admission plasma sodium concentration ([Na]) in horses with septic pneumopathy and evaluate any association of plasma [Na] with markers of systemic inflammation. ANIMALS: Medical records of horses >1&#xa0;month of age that between 2008 and 2021 had a transtracheal aspirate (TTA) performed, abnormal TTA cytology, positive TTA culture, pulmonary disease on ultrasonography, radiography or both, and plasma [Na] assessed by direct ion-selective-electrode (dISE). Horses with concurrent diarrhea or azotemia were excluded. METHODS: Clinical and clinicopathological variables of interest between hypo- and normonatremic horses were compared. Spearman correlation and Fisher exact tests were used to identify significant associations (P&#x2009;<&#x2009;.05). RESULTS: Twenty of 35 horses had hyponatremia (median, 132&#x2009;mmol/L; 25-75th interquartile range [IQR], 129.7-133.1&#x2009;mmol/L; reference range, 134.2-138.4&#x2009;mmol/L). A higher proportion of horses with systemic inflammatory response syndrome (SIRS) had hyponatremia (P&#xa0;=&#xa0;.01). Hyponatremic patients had higher mean plasma fibrinogen concentration (461&#x2009;&#xb1;&#x2009;160.5&#xa0;mg/dL; P&#xa0;=&#xa0;.01) and higher rectal temperature (38.8&#x2009;&#xb1;&#x2009;0.7&#xb0;C; P&#xa0;=&#xa0;.02) than normonatremic horses. Negative correlations were found between plasma [Na] and fibrinogen (P&#xa0;=&#xa0;.001; &#x3c1;&#xa0;=&#xa0;-0.57) concentrations and between plasma [Na] and rectal temperature (P&#xa0;=&#xa0;.001; &#x3c1;&#xa0;=&#xa0;-0.51). Presence or absence of pleural effusion did not influence severity of hyponatremia. Mean duration of hospitalization was longer (P&#xa0;=&#xa0;.04) in hyponatremic horses (9.8&#x2009;&#xb1;&#x2009;6.6&#x2009;days). CONCLUSIONS AND CLINICAL IMPORTANCE: Hyponatremia at admission is associated with the presence of inflammation, SIRS, and with longer duration of hospitalization.