Clinical Connections - Summer 2019

Justin Perkins: Senior Lecturer for Equine Surgery and European Specialist in Large Animal Surgery
EXCITING ADVANCES IN THE TREATMENT OF RECURRENT LARYNGEAL NEUROPATHY
ecurrent laryngeal neuropathy athletic performance and turbulent be effective in improving airway impedance (RLN) remains a significant cause of airflow. Diagnosis is made using resting in horses with experimentally induced poor performance in horses. Recent endoscopy, exercising endoscopy, and laryngeal hemiplegia following transection
research has identified pathological changes consistent with the presence of RLN
in almost all Thoroughbred racehorses, suggesting that the subclinical prevalence of the condition is much higher than previously reported.
The pathogenesis of the condition is yet to be fully understood, but it is thought that a distal axonopathy, which predominantly affects the left recurrent laryngeal nerve, results in neurogenic atrophy of the laryngeal muscles.
Clinical signs associated with RLN develop due to dysfunction of the
sole abductor of the larynx – the cricoarytenoideus dorsalis muscle. This can lead to inspiratory obstruction, reduced
ultrasound examination of the larynx – or a combination of the above.
The prosthetic laryngoplasty (PL)
(‘tie back’; alone or in combination with unilateral or bilateral ventriculectomy, vocal cordectomy or both) remains the most commonly employed treatment for RLN. This procedure has undergone modification since described by Marks et al in 1970, however the success of PL in Thoroughbred horses is only modest and commonly associated with significant postoperative complications, including prosthesis failure, dysphagia, and inhalation pneumonia.
Laryngeal re-innervation via the nerve muscle pedicle graft has been described as an alternative to PL. It had been shown to
of the recurrent laryngeal nerve. However, follow up clinical studies demonstrated
a success rate similar to that of PL, with up to one year required for functional reinnervation.Widespread use of this technique has perhaps been precluded
by the technical difficulty in performing the procedure, and the requirement for prolonged rehabilitation rendering it less suitable as a treatment for older horses.
Recently, a modified first or second cervical nerve transplantation technique developed by Justin Perkins, Lecturer in Equine Surgery at the RVC, has shown promising results as a method of re- innervation of the larynx for horses with RLN. In this procedure, direct implantation
CLINICAL CONNECTIONS RVC Clinical Services Newsletter Summer 2019
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SPECIAL CARE FOR COMMON RABBIT TRANSVENOUS PDA CT OF THE CERVICAL BELGIAN GREAT DANE REFERRAL CASES OCCLUSION SPINE IN HORSES
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