Tim Barnett, RCVS and European Veterinary Specialist in Equine Surgery, talks to us about the latest developments in upper airway diagnostics ahead of the upper airways discussion forum from rossdales Equine Hospital.
Equine upper airway diagnostic procedures and treatments are currently evolving at a remarkable pace. Exercising overground endoscopic examination (OGE) has been in use for over 10 years now, and has probably provided the biggest advancement in the diagnosis of upper airway disease. With a greater acceptance than high speed treadmill endoscopy; this technique appears to have delivered a more accurate diagnosis in many more horses than using resting endoscopic examination alone. OGE can complement the usual training regime of the horse, and allow a rider to add weight, provide control and execute equitation manoeuvres specific to the individual patient. For example, some forms of upper airway collapse are only seen at times of increased poll flexion.
Palatal dysfunction, including dorsal displacement of the soft palate (DDSP) has long been problematic, both with regards to diagnosis and treatment. The clinical signs reported are often only encountered when the horse is competing at a high intensity which, even with the use of OGE, is hard to replicate under training conditions. The aetiology of the condition is still not fully elucidated, and it is possible that it may be multifactorial. There are a number of treatment options available to horses with suspected and diagnosed palatal dysfunction. A number of conservative methods, some of which involve modifications of the tack and training regimes, have been used to good effect. Palatal thermocautery is controversial but frequently undertaken in the UK and Ireland, with reported success in alleviating the clinical signs of some horses. The laryngeal tie-forward procedure has been described as having the greatest success with regards to post-operative racing performance of horses, and is often combined with other treatment strategies.
Traditional surgical interventions have considerably been refined, and the introduction of the medical laser has meant vocal fold, ventricle and aryepiglottic fold resections are now performed in the standing patient, without the need to make a laryngotomy incision. In addition, the tie-back procedure for recurrent laryngeal neuropathy (RLN) can now be performed in the standing, sedated patient with the benefit of region-specific nerve blocks . New suturing and anchoring methods have also been introduced, and appear to be providing greater success compared to traditional methods.
When diagnosed early enough in the disease process RLN can also be treated using a nerve graft, and in some cases with the addition of a pacemaker. The concept of a nerve graft has been around for many years, but a refinement of the technique has improved both the short- and long-term success. The time it takes to condition the atrophied Cricoarytenoideus dorsalis (CAD) muscle after implantation of the new nerve is still the limiting factor in many competition horses. A laryngeal pacemaker has been developed that has been used to stimulate the implanted nerve and aims to train the CAD at times when the horse is resting, thus accelerating the recovery period for the horse. It is hoped that this technology will mean that this surgery can become an option in horses in training in the future, and possibly also applied to other muscles of the upper airway in a similar way.
Want to find out more and get involved in an open discussion on the topic?
Join Tim and other leading clinicians from around the world on Friday 22 February 2019 for evidence-based lectures covering this latest research as well as an opportunity for an open discussion with colleagues looking at:
- How accurate and repeatable is exercising endoscopy?
- How successful are conservative methods of treatment DDSP?
- Choosing the best prosthesis and method for laryngoplasty
- The future of nerve grafts and the pacemaker
- Regenerative medicine applications for the equine upper airway
For more information and to register please contact Rachel Clay firstname.lastname@example.org or call (0)1638 577754
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