Thirst and salt appetite in horses treated with furosemide.

The research investigated the impact of furosemide treatment on the salt intake and water consumption of horses. It suggested that the treatment increases both salt appetite and thirst in horses, particularly in those with reduced sodium levels, indicating that they tend to undercompensate for sodium loss after furosemide administration.

Research Method and Experimentation

• Initially, a preliminary experiment was carried out on ponies that had normal sodium levels. This test showed an increase in salt consumption post furosemide treatment but the increase was not significant enough.
• To further investigate, the study was conducted on horses with deficient sodium levels where aldosterone (a hormone that regulates salt balance) levels tend to be high. The researchers hypothesized that the presence of aldosterone might instigate salt appetite in such situations.
• For the experiment, ten Standardbred mares were selected and intravenously injected with either furosemide or a 0.9% volume of sodium chloride (as a control).

Monitoring and Gathering Data

• The effect of furosemide on the salt appetite of the horses was gauged. Important parameters such as sodium intake, sodium loss in urine, water intake, and urine output were measured.
• These measurements served to ascertain the accuracy with which the horses compensated for the increased excretion of sodium (natriuresis) and increased urine output (diuresis) after receiving furosemide.
• Blood constituents were also tested to rule out other factors that might impact the results. Specifically, levels of plasma protein and packed cell volume showed significant elevation upon receiving furosemide.

Findings and Conclusions

• The findings revealed no considerable alteration in plasma sodium concentration or osmolality (solute concentration) subsequent to furosemide treatment.
• The salt intake in horses treated with furosemide significantly increased, indicating a rise in salt appetite. Moreover, these horses also drank more water, signaling an increase in thirst as well.
• It was found that horses were undercompensating for the increased sodium loss with their increased sodium intake post-furosemide treatment.
• In summary, the study suggests furosemide treatment induces both a heightened salt appetite and thirst in horses, particularly those with sodium deficiency. However, the intake of sodium in these horses was insufficient to compensate for the sodium loss.