Induced diarrhoea in horses. Part 2: Response to administration of an oral rehydration solution.

The study investigates the impact of an orally administered rehydration solution (ORS) on horses that have been induced with diarrhoea using castor oil. Findings suggest that while ORS can aid in restoring fluid balance, the effectiveness may be influenced by factors such as the ionic composition of the ORS and the rate at which it is administered.

Research Context and Methodology

• The experiment involved four adult standardbred gelding horses, purposely induced with diarrhoea using castor oil.
• The researchers monitored the hydration status, the balance of electrolytes and acid-base balance of the horses.
• The horses received an oral rehydration solution (ORS) when symptoms indicative of minor decreases in the effective circulating fluid volume were first observed.

Results and Findings

• Within 1.5 hours of ORS administration, all the horses showed substantial metabolic acidosis, signified by specific mean values for venous blood pH, HCO3 (bicarbonate), and standard base excess.
• Though there was a trend for reducing plasma volume, it did not change significantly, and it began approaching normal values about 8 hours after the ORS administration.
• All horses exhibited signs of abdominal discomfort after the last dosage of ORS given at 30 minutes intervals.
• A significant increase in the concentration of sodium in faecal fluid was noted with diarrhoea, reaching values four times those typically observed in healthy horses.
• Even with this increase in sodium concentration, the faecal fluid remained hypotonic throughout.

Conclusions and Implications

• While ORS can help restore systemic fluid balance, several factors affect their efficacy. Two noteworthy factors identified in this study were the ionic composition of the ORS and the rapidity of administration.
• The researchers concluded that the electrolyte composition of current ORS may not be perfectly suitable to treat diarrhoea in horses.
• It was also inferred that administering 8-10 litres of ORS every 30 minutes via a nasogastric tube could result in excessively swift small intestinal transit, leaving insufficient time for absorption.

The significant contribution of the study is in highlighting the inefficiencies in the current practices to handle diarrhoea in horses and suggesting scopes for improvement.