Induced diarrhoea in horses. Part 1: Fluid and electrolyte balance.

This study examines the effect of castor oil induced diarrhoea on the electrolyte balance in horses, focusing on sodium, potassium and water levels. The findings suggest that diarrhoea leads to the significant loss of these elements, potentially causing dehydration.

Study Overview and Design

• The researchers conducted a study on four adult standardbred geldings which are male horses.
• The diarrhoea was induced using castor oil, a known laxative. The dosage used was 2 mL kg-1.
• They measured various parameters including sodium, potassium, water balance, acid-base status, haematocrit, packed cell volume, and plasma total protein.
• These measurements were monitored after inducing diarrhoea to evaluate its effects.

Effects of Castor Oil Induced Diarrhoea

• The administration of castor oil led to symptoms consistent with mild to moderate acute colitis. Colitis is inflammation of the colon which can lead to diarrhoea.
• The total losses of sodium and potassium ions, including through fecal and urinary excretion, were 2169 and 2864 mmol respectively.
• Sodium was primarily lost through feces, while potassium was mainly excreted in urine.
• The concentration of potassium in the dry matter of faeces remained relatively stable throughout the period of the study. However, the sodium concentration increased significantly, especially with the onset of clinical diarrhoea.

Impact on Water Loss and Plasma Volume

• The study noted a significant increase in fecal water loss from 2.15 +/- 0.44 mL kg-1 h-1 to 5.15 +/- 0.92 mL kg-1 h-1 during the observed clinical diarrhoea. This suggests that diarrhoea significantly contributes to dehydration in horses.
• The plasma volume did not significantly vary during the study, but there was an observed trend for it to decrease during periods of clinical dehydration.

In conclusion, the study highlights the significant impact of diarrhoea on the electrolyte and fluid balance in horses and provides valuable insights for equine health management.