Effect of clenbuterol on arterial oxygen tension in the anaesthetised horse.

The research paper studies the effect of clenbuterol; a bronchodilator, on the arterial oxygen tension in anaesthetised horses. The findings show a significant increase in arterial oxygen tension when the horses were given clenbuterol, indicating its potential to boost oxygen levels in anaesthetised horses.

Study Methodology

• The study was conducted on horses that were in dorsal recumbency, i.e., lying on their backs, and breath spontaneously on oxygen.
• The horses were maintained on a constant end-tidal concentration of halothane, an anesthetic used in veterinary medicine.
• Two different doses of clenbuterol, an asthma medication often used in horses, were administered to the horses: 0.8 micrograms kg-1 and 2.4 micrograms kg-1.
• Another set of horses were initially in dorsal recumbency and then turned to sternal recumbency (lying on their chest) without ingesting clenbuterol.

Research Findings

• Among the horses in dorsal recumbency, the arterial oxygen tension (a measure of the amount of oxygen available to the body’s tissues) increased significantly from 9.9 kPa initially to 21.7 kPa with the lower dose of clenbuterol, and 29.1 kPa with the higher dose.
• Without clenbuterol, arterial oxygen tension in horses initially in dorsal recumbency then turned to sternal recumbency rose to 54.0 kPa, but this rise was unaffected by clenbuterol administration.
• The increase in arterial oxygen tension during dorsal recumbency indicates that clenbuterol counteracts some factor believed to direct pulmonary blood flow in the caudodorsal (towards the back and tail) direction.
• However, the response to clenbuterol in sternal recumbency was not similar, indicating a different interaction or mechanism in this recumbency position.

Conclusion

• The study couldn’t conclusively identify the pulmonary factor that clenbuterol potentially counteracts. However, the results displayed the prominent effect of clenbuterol in increasing arterial oxygen tension.
• This effect brings to the forefront the potential of using clenbuterol as a treatment to increase arterial oxygen tension levels often seen in anaesthetised horses, potentially enhancing their recovery and overall health status.