Laryngeal Advancement Surgery Improves Swallowing Function in a Reversible Equine Dysphagia Model

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A new article from the Equine Veterinary Journal on wiley.com is titled “Laryngeal advancement surgery improves swallowing function in a reversible equine dysphagia model.”Researchers from Michigan State University and Cornell University looked at a type of surgery to help “diminish dysphagia symptoms and improve swallowing in affected horses. Following is information from this article.

http://onlinelibrary.wiley.com/doi/10.1111/evj.12430/abstract

Summary

Reasons for performing the study

Pharyngeal dysphagia is a debilitating, sometimes fatal condition in horses with multiple etiologies. The pathophysiology is complex and not fully understood. Treatment is largely supportive. Laryngeal advancement surgery may diminish dysphagia symptoms and improve swallowing in affected horses.

Objectives

1) Induce reversible moderate and marked pharyngeal dysphagia by regional anaesthesia of branches of the glossopharyngeal (IX), vagus (X), and hypoglossal (XII) nerves, 2) Characterise the dysphagia produced by each model, and 3) Determine if laryngeal advancement surgery improves swallowing in these models.

Study Design

Experimental design using 6 adult horses.

Methods

Two dysphagia models were produced by blocking IX, the pharyngeal branch of X (pX) and XII unilaterally (moderate model) and only pX bilaterally (marked model) within the guttural pouches. Both models were performed on each horse before and after surgery in order to assess the effectiveness of the surgical procedure as a potential treatment for pharyngeal dysphagia. Dysphagia was scored by partially blinded observers on a scale of 0 - 12 based on observations of eating (non-blinded), endoscopic examinations and fluoroscopic swallowing (blinded), where 0 = normal swallow and 12 = severe dysphagia with tracheal aspiration. Data were analysed by 3-factor ANOVA, p<0.05.

Results

Dysphagia models were reversible and horses swallowed normally within 3 h of model induction. The marked dysphagia model impaired movement of feed from the base of the tongue to the oesophagus and caused severe airway contamination. Average dysphagia score (mean ± s.d.) for the marked dysphagia model prior to surgery was 10.6 ± 1.1 and 6.1 ± 4.3 after surgery, p = 0.007. Laryngeal advancement surgery did not significantly improve the dysphagia scores in the moderate model, p = 0.5.

Conclusions

Laryngeal advancement surgery may improve swallowing and reduce aspiration in horses affected with diseases that cause pharyngeal dysphagia.

Authors

1. J. E. Virgin1,

2. S. J. Holcombe1,*,

3. J. P. Caron1,

4. J. Cheetham3,

5. K. A. Kurtz1,

6. H. A. Roessner1,

7. N. G. Ducharme3,

8. J. G. Hauptman2 and

9. N. C. Nelson2

1. 1

Department of Large, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA

2. 2

Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA

3. 3

Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA