Respiratory and metabolic effects of massive administration of isotonic saline solution in heaves-affected and control horses.

The research examines the physiological effects of rapidly administering isotonic saline solution to horses suffering from heaves, a chronic airway disease. The study finds that this treatment neither improves lung function nor is effective against heaves, but instead leads to temporary side effects.

Methodology

• The study included two different groups: a control group consisting of 5 healthy horses (Group C) and a second group of 9 horses affected by heaves (Group H).
• The method of the experiment involved the intravenous administration of isotonic saline solution, a volume of thirty litres to each horse.
• The researchers assessed the horses before the saline infusion, during the infusion (at 90 and 180 minutes), and then at 1, 3, 6, and 10 days post-infusion.
• Assessments in the form of Pulmonary function testing and arterial blood gas analysis were carried out.
• Vitals including PCV (Packed Cell Volume), plasma total solids, plasma electrolytes (sodium, chloride, and potassium) and venous blood gas were also recorded before, during, and after the saline infusion.

Findings

• Upon administering the isotonic saline solution, horses in the heaves-affected group (Group H) showed no significant improvement in their lung function during the infusion.
• 180 minutes after beginning the infusion, the pulmonary resistance of horses in Group H had notably increased.
• Similarly, horses in the control group (Group C) experienced an increase in pulmonary resistance 180 mins post saline initiation and a significant reduction in arterial oxygen tension (PaO2) at 90 minutes.
• These findings indicate a temporary decrease in lung function caused by the rapid administration of saline – contrary to previous suggestions that isotonic saline solution may relieve airway obstruction in heaves.
• At the beginning of the study, the horses in Group H were noted to have metabolic alkalosis with low chloride levels. This condition resolved following the administration of the isotonic saline solution, but reverted back six hours after discontinuing the treatment.

Conclusions

• The findings of this study contradict the assumption that rapid administration of isotonic saline solution improves lung function in horses affected by heaves.
• On the contrary, this intervention led to only temporary side effects, including an increase in pulmonary resistance, and was not found to be an effective therapeutic approach for heaves.