A case of equine laryngospasm.

This research presents a unique case of laryngospasm in a horse, a condition that is often observed in cats and other domestic animals, but rarely reported in horses. Traditional methodologies and practices were applied in diagnosing and studying this particular case.

Case Introduction and Methodology

• The study revolves around a case of a 20-year-old thoroughbred mare, that was in good physical shape and part of a series of animals destined for electromyographic investigation into laryngeal physiology.
• No abnormalities were noted in the clinical examination before the procedure. The mare was pre-medicated with acetylpromazine and anesthetized with thiopentone sodium.
• Anesthesia was sustained with a halothane/oxygen mix, delivered via a to-and-fro anesthesia apparatus. The mare was placed in a left lateral recumbency position.
• The dorsal laryngeal area was exposed through the ventral approach, as described by Marks et al. (1970).

Procedure and Observations

• Electromyographic recordings were taken from the intrinsic laryngeal muscles using a technique comparable to that described by Shipp et al, (1970), whereby a concentric needle was substituted for the wire electrode.
• A rhinolaryngoscope was inserted into the throat after the endotracheal tube removal to observe laryngeal movements.
• A high-frequency discharge or “spasm” was provoked and recorded from the lateral cricoarytenoid muscle after inadvertently pushing the rhinolaryngoscope against the posterior mucosa of the pharynx close to corniculate part of arytenoid cartilages.
• At this point, the horse stopped breathing and the arytenoid cartilages adjoined to occlude the dorsal area of the glottis. This prolonged for more than a minute without any sign of respiratory movement from the horse.

Concluding Observations

• After the minute-long gap, the horse began breathing again, but the electromyographic pattern had changed significantly compared to the data gathered before the “spasm”.
• This anomalous electromyographic pattern persisted for a few respirations, before the pattern returned to the pre-spasm norm.

The researchers thus documented a significant and unusual equine laryngospasm, which contributed to the broader knowledge of pathological conditions in horses.