{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T16:21:27Z","timestamp":1783009287731,"version":"3.54.5"},"reference-count":16,"publisher":"American Veterinary Medical Association (AVMA)","issue":"7","license":[{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2026,7,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"sc_a1\">\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>In clinical research, laryngeal hemiplegia (LH) is induced by temporarily supressing recurrent laryngeal nerve function; however, the technique is challenging. The aim was to develop a novel method to induce LH by injecting bupivacaine directly into the cricoarytenoid dorsalis (CAD) muscle with ultrasound guidance.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a2\">\n                    <jats:title>Animals<\/jats:title>\n                    <jats:p>5 cadaver larynges and 9 Thoroughbreds with normal laryngeal function.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a3\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Part 1: A high-frequency (6.5- to 13.0-MHz) linear ultrasound probe was used to inject methylene blue (5 mL) into the CAD of 5 cadaver larynges. Part 2: The left side of the larynges of 9 horses were aseptically prepared, and the cricoid, thyroid, and arytenoid cartilages were identified with ultrasonography. With the use of a horizontal view dorsally, the cricoarytenoid lateralis muscle was visualized, followed by the arytenoid cartilage and CAD superficial to the cricoarytenoid joint. An 18-gauge, 3.5-inch spinal needle was advanced into the left CAD under ultrasound guidance. Bupivacaine was injected (0.5% concentration, 4.5 mL). Part 3: The efficiency, reversibility, and duration of LH was assessed at rest and during maximal treadmill exercise with overground endoscopy. Laryngeal function was reassessed 1 week later.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a4\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>All cadaver larynges showed evidence of methylene blue in the CAD, confirming that ultrasonography can be used to inject the CAD. Laryngeal hemiplegia was observed within 5 minutes of injection (grade IV), continued throughout exercise (grade D), and persisted for 70 to 90 minutes after exercise (grade IV). Horses had normal CAD echogenicity and laryngeal function at rest and exercise 7 days after injection.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sc_a5\">\n                    <jats:title>Clinical Relevance<\/jats:title>\n                    <jats:p>Injecting bupivacaine into the CAD under ultrasound guidance is a practical technique for inducing transient LH that is sustainable during maximal exercise.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.2460\/ajvr.26.01.0025","type":"journal-article","created":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T21:05:48Z","timestamp":1775163948000},"source":"Crossref","is-referenced-by-count":0,"title":["Ultrasound-guided injection of bupivacaine into the cricoarytenoid dorsalis muscle as a novel technique for transiently inducing laryngeal hemiplegia in horses"],"prefix":"10.2460","volume":"87","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-3933-4621","authenticated-orcid":true,"given":"Shannon","family":"Massie","sequence":"first","affiliation":[{"name":"Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1403-6245","authenticated-orcid":true,"given":"Warwick M.","family":"Bayly","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Washington State University, Pullman, WA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2139-6142","authenticated-orcid":true,"given":"Yuji","family":"Takahashi","sequence":"additional","affiliation":[{"name":"Equine Research Institute, Japan Racing Association, Shimotsuke-shi, Tochigi, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0381-3640","authenticated-orcid":true,"given":"Renaud","family":"L\u00e9guillette","sequence":"additional","affiliation":[{"name":"Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1272","reference":[{"issue":"1","key":"B1","series-title":"Vet Surg","first-page":"36","article-title":"The effect of reversible left recurrent laryngeal neuropathy on the metabolic cost of locomotion and peak aerobic power in Thoroughbred racehorses","volume":"24","author":"Ehrlich PJ","year":"1995","unstructured":"Ehrlich PJ, Seeherman HJ, Morris E, Kolias C, Cook WR. The effect of reversible left recurrent laryngeal neuropathy on the metabolic cost of locomotion and peak aerobic power in Thoroughbred racehorses. Vet Surg. 1995;24(1):36\u201348. doi:10.1111\/j.1532-950X.1995.tb01291.x"},{"issue":"suppl 18","key":"B2","series-title":"Equine Vet J","first-page":"7","article-title":"Physiological versus clinical consequences of left recurrent laryngeal neuropathy (LRLN)","volume":"27","author":"Seeherman HJ","year":"1995","unstructured":"Seeherman HJ, Ehrlich PJ, Morris E. Physiological versus clinical consequences of left recurrent laryngeal neuropathy (LRLN). Equine Vet J. 1995;27(suppl 18):7\u201312. doi:10.1111\/j.2042-3306.1995.tb04881.x"},{"key":"B3","first-page":"s5","article-title":"Ventilatory response to incremental exercise using a reversible model of LRLN in horses","author":"Morris E","year":"1991","unstructured":"Morris E, Beltz J, Seeherman H, et\u00a0al. Ventilatory response to incremental exercise using a reversible model of LRLN in horses. In Proceedings: Vet Respir Symp 1991; 10:s5"},{"issue":"8","key":"B4","series-title":"Am J Vet Res","first-page":"897","article-title":"Effects of airway obstruction on transmural pulmonary artery pressure in exercising horses","volume":"58","author":"Jackson JA","year":"1997","unstructured":"Jackson JA, Ducharme NG, Hackett RP, et\u00a0al. Effects of airway obstruction on transmural pulmonary artery pressure in exercising horses. Am J Vet Res. 1997;58(8):897\u2013903. doi:10.2460\/ajvr.1997.58.08.897"},{"issue":"30","key":"B5","series-title":"Equine Vet J Suppl","first-page":"27","article-title":"Pulmonary capillary pressure in horses undergoing alteration of pleural pressure by imposition of various upper airway resistive loads","volume":"31","author":"Ducharme NG","year":"1999","unstructured":"Ducharme NG, Hackett RP, Gleed RD, et\u00a0al. Pulmonary capillary pressure in horses undergoing alteration of pleural pressure by imposition of various upper airway resistive loads. Equine Vet J Suppl. 1999;31(30):27\u201333. doi:10.1111\/j.2042-3306.1999.tb05183.x"},{"issue":"5","key":"B6","series-title":"Am J Vet Res","first-page":"659","article-title":"Spectrum analysis of respiratory sounds in exercising horses with experimentally induced laryngeal hemiplegia or dorsal displacement of the soft palate","author":"Derksen FJ","year":"2001","unstructured":"Derksen FJ, Holcombe SJ, Hartmann W, Robinson NE, Stick JA. Spectrum analysis of respiratory sounds in exercising horses with experimentally induced laryngeal hemiplegia or dorsal displacement of the soft palate. 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