Ultrasound spirometry in the horse: a preliminary report on the method and the effects of xylazine and lobeline hydrochloride medication.

The researchers in the study evaluated the effectiveness of a novel ultrasound spirometry method on both healthy horses and those affected with chronic bronchiolitis (CB). Furthermore, they examined the effects of medications, specifically xylazine and lobeline hydrochloride, on various spirometric variables.

Methodology

The study utilized an innovative approach by integrating a computerized ultrasound-based spirometry system with a dual flow measurement facility. This system originally devised by Buess et al. (1995) was slightly modified.

• The horses were first tested at rest, without administering any medication.
• Later, an intravenous administration of xylazine (0.4 mg/kg) was done to test the impacts of this drug on various spirometric variables.
• Similar tests were repeated after the administration of lobeline hydrochloride (0.2 mg/kg), to assess its relative effects.

Findings

The study discovered that the ultrasound-based spirometry method is an easy-to-apply procedure for testing lung function, even in hard-to-test horses. However, the researchers found significant physiological variations in all the measured lung function parameters.

• Despite this variation, no significant differences between the lung function of healthy horses and horses with chronic bronchiolitis were correspondent, except for the expiratory tidal volume (variable VTE).
• After xylazine or lobeline hydrochloride injection, there was a noticeable decrease in breath-to-breath variability for all parameters, apart from the flow-time-ratio (Tpef./Texp.) and the flow-volume-ratio (Vpef./Vexp.).

This indicates the possible efficiency of these two drugs in controlling and regulating the lung function parameters.

Conclusion

Thus, this study contributed valuable insights regarding the utility of ultrasound spirometry in horses and the effects of specific medications on their respiratory variables. These findings may inform future research and clinical applications in equine respiratory health.