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Comparison of morphological changes and tactile sensitivity of the pharynx and larynx between four standing sedative and analgesic protocols in eight adult healthy horses

  • Guillaume Manneveau
    Correspondence
    Correspondence: Guillaume Manneveau, Department of Surgery, Equine Clinic, ONIRIS, National College of Veterinary Medicine, Food Science and Engineering, Atlanpôle-La Chantrerie, 44307 Nantes Cedex 03, France.
    Affiliations
    Department of Surgery, Equine Clinic, ONIRIS, National College of Veterinary Medicine, Food Science and Engineering, Nantes, France
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  • Jeanne Lecallard
    Affiliations
    Department of Surgery, Equine Clinic, ONIRIS, National College of Veterinary Medicine, Food Science and Engineering, Nantes, France
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  • Chantal Thorin
    Affiliations
    Department of Animal Physiopathology and Pharmacology, ONIRIS, National College of Veterinary Medicine, Food Science and Engineering, Nantes, France
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  • Hugo Pamela
    Affiliations
    Department of Anaesthesia and Analgesia, Equine Clinic, ONIRIS, National College of Veterinary Medicine, Food Science and Engineering, Nantes, France
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  • Caroline Tessier
    Affiliations
    Department of Surgery, Equine Clinic, ONIRIS, National College of Veterinary Medicine, Food Science and Engineering, Nantes, France
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Published:April 30, 2018DOI:https://doi.org/10.1016/j.vaa.2018.02.011

      Abstract

      Objective

      To compare the topographic modifications and tactile sensitivity of the pharynx and larynx after administration of four sedative and analgesic protocols in standing horses.

      Study design

      Experimental, observer-blinded, crossover study.

      Animals

      Eight healthy mares.

      Methods

      Five protocols were evaluated: 1) xylazine and butorphanol administered intravenously (IV); 2) detomidine and butorphanol administered IV; 3) xylazine administered IV and lidocaine topically; 4) detomidine administered IV and lidocaine topically and 5) no analgesia or sedation (control). Quality of sedation, head height and sudden head movements were recorded. The degree of arytenoid cartilage displacement, the degree of pharyngeal collapse and the occurrence of soft palate displacement were scored using standardized scales. Tactile sensitivity was tested on 10 different pharyngeal and laryngeal regions using an atraumatic transendoscopic probe. Statistical analysis was performed using linear or generalized mixed-effects models.

      Results

      Head height was significantly decreased in protocols with xylazine (p = 0.002). Head movements were significantly increased in protocols with butorphanol (p = 0.0001). No changes in abduction grade or degree of soft palate displacement were observed between all sedative protocols and the control group. Pharyngeal collapse was significantly more frequent in protocols with lidocaine (p < 0.001) or xylazine (p = 0.017). For the pharyngeal regions, no tactile sensitivity difference was observed between the control and treatment protocols. All treatment protocols led to greater desensitization of all the laryngeal regions compared with the control protocol.

      Conclusion and clinical relevance

      All the protocols provided adequate sedation and analgesia for the manipulation of the larynx and pharynx but significant differences were noted. Xylazine produces a more profound sedation compared with detomidine, but can induce dorsal pharyngeal collapse. Lidocaine caused pharyngeal collapse and its use should be limited to the target area. Butorphanol can be added to improve analgesia in the other regions but frequent head jerking can be expected.

      Keywords

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