Hyponatremia in horses with septic pneumopathy

Area of Science:

• Veterinary Medicine
• Equine Health
• Internal Medicine

Background:

• Hyponatremia is frequently observed in horses diagnosed with bacterial pleuropneumonia.
• However, a detailed characterization of this electrolyte imbalance in affected horses has been lacking.

Purpose of the Study:

• To document plasma sodium concentration ([Na]) upon admission in horses suffering from septic pneumopathy.
• To investigate potential correlations between plasma [Na] and indicators of systemic inflammation in these horses.

Main Methods:

• Retrospective analysis of medical records from horses (age >1 month) diagnosed with bacterial pneumonia between 2008 and 2021.
• Inclusion criteria involved abnormal transtracheal aspirate (TTA) cytology, positive TTA culture, and pulmonary disease confirmed via imaging.
• Plasma [Na] was measured using direct ion-selective-electrode (dISE) method; horses with diarrhea or azotemia were excluded.

Main Results:

• Twenty out of 35 horses presented with hyponatremia (median [Na] 132 mmol/L).
• Hyponatremic horses showed a higher prevalence of systemic inflammatory response syndrome (SIRS), elevated plasma fibrinogen, and higher rectal temperatures.
• A significant negative correlation was observed between plasma [Na] and both fibrinogen levels and rectal temperature.

Conclusions:

• Admission hyponatremia in horses with septic pneumopathy is associated with heightened systemic inflammation and SIRS.
• Hyponatremic horses experienced a longer duration of hospitalization compared to their normonatremic counterparts.