Bilateral arytenoid cartilage paralysis after inhalation anesthesia in a horse.

This research article describes a case of an 8-year-old Quarter Horse experiencing bilateral arytenoid cartilage paralysis apparently as a result of inhalation anesthesia during a surgical procedure.

Case Presentation

• The research article presents the case of an 8-year-old Quarter Horse who underwent inhalation anesthesia for surgery to explore and clean out a persistent wound in the intermandibular space (the region between the lower jawbones).
• Despite the anesthesia procedure not encountering any significant hitches, the horse did present with abnormally low levels of oxygen in the arterial blood (PaO2) throughout the period of anesthesia.
• Upon wakening and removal of the endotracheal tube (extubation), the horse displayed severe difficulty in breathing, necessitating the prompt opening of a direct airway through the neck into the trachea (tracheostomy).
• Examination via endoscopy revealed that the horse’s breathing difficulties stemmed from bilateral arytenoid paralysis, a condition in which the cartilages controlling airflow at the larynx are unable to function properly, thereby obstructing breathing.

Likely Causes

• Existing veterinary literature suggests that this condition may arise due to damage or pressure exerted on the recurrent laryngeal nerves, resulting in their impaired function – a condition described as idiopathic laryngeal hemiplegia (ILH).
• In the particular case of this horse, its extended position of the head and neck during the anesthesia, possibly along with the lowered levels of oxygen in the blood, might have posed a hypoxemic (insufficient oxygen) challenge to the recurrent laryngeal nerves, thereby triggering the arytenoid paralysis.

Outcome and Recovery

• Interestingly, the horse’s paralysis appeared to resolve naturally over a week’s time, without necessitating surgical intervention or drug treatment.

This piece of research contributes to the understanding of the possible complications that may occur following inhalation anesthesia in horses, with the unique case shedding light on the potential links between anesthesia, the position of the animal during surgery, and resultant nervous system impacts.