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Objective: To compare the effects of thiopentone, propofol and alfaxalone on arytenoid cartilage motion and establish the dose rates to achieve a consistent oral laryngoscopy examination., Study Design: Randomised crossover study., Animals: Six healthy adult Beagle dogs., Methods: Each dog was randomly administered three induction agents with a 1-week washout period between treatments. Thiopentone (7.5 mg kg -1 ), propofol (3 mg kg -1 ) or alfaxalone (1.5 mg kg -1 ) was administered over 1 minute for induction of anaesthesia. If the dog was deemed inadequately anaesthetised, then supplemental boluses of 1.8, 0.75 and 0.4 mg kg -1 were administered, respectively. Continual examination of the larynx, using a laryngoscope, commenced once an adequate anaesthetic depth was reached until examination end point. The number of arytenoid motions and vital breaths were counted during three time periods and compared over time and among treatments. Data were analysed using Friedman and Mann-Whitney U tests, Spearman rho and a linear mixed model with post hoc pairwise comparison with Tukey correction., Results: The median (range) induction and examination times were 2.8 (2.0-3.0), 2.7 (2.0-3.3) and 2.5 (1.7-3.3) minutes (p = 0.727); and 14.1 (8.0-41.8), 5.4 (3.3-14.8) and 8.5 (3.8-31.6) minutes (p = 0.016) for thiopentone, propofol and alfaxalone, respectively. The median dose rates required to achieve an adequate anaesthetic depth were 6.3 (6.0-6.6), 2.4 (2.4-2.4) and 1.2 (1.2-1.2) mg kg -1  minute -1 , respectively. There was no significant difference for the total number of arytenoid motions (p = 0.662) or vital breaths (p = 0.789) among induction agents., Conclusion and Clinical Relevance: The number of arytenoid motions were similar among the induction agents. However, at the dose rates used in this study, propofol provided adequate conditions for evaluation of the larynx with a shorter examination time which may be advantageous during laryngoscopy in dogs., (Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objectives: To objectively measure and subjectively score the effect of 3 anesthetic induction protocols on arytenoid cartilage motion in normal cats., Study Design: Randomized prospective clinical study., Animals: Cats (n = 35) without previous history of respiratory dysfunction., Methods: Cats were randomly assigned to administration of alfaxalone, propofol, or midazolam and ketamine to induce anesthesia after premedication with methadone. Videolaryngoscopy was performed. Still images at maximum inspiration and expiration were used to measure the area and height of the rima glottidis. Change in rima glottidis area and of normalized glottal gap area (NGGA = area/height(2) ) was calculated. Subjective scores for arytenoid movement were obtained. Kruskal-Wallis test was performed on change of NGGA and rima glottidis area., Results: No statistically significant difference was found between groups for age, sex, body weight, and body condition score. Percentage increase of rima glottidis area and change in NGGA were similar for all groups (P = .33 and P = .29). No significant differences were found for subjective scores between groups (P = .54). Arytenoid movement was not detected during videolaryngoscopy and subjective scoring in 3 cats anesthetized with propofol and in 3 cats anesthetized with midazolam and ketamine, despite presence of respiratory movements., Conclusions: No difference in laryngeal motion was observed between the 3 protocols used to induce anesthesia in cats premedicated with methadone., (© Copyright 2012 by The American College of Veterinary Surgeons.)

OBJECTIVE-To determine the association between results of endoscopic evaluation of arytenoid function (AF) and epiglottic structure (ES) in Thoroughbred yearlings and racing performance at 2 to 4 years of age. DESIGN-Retrospective case series. ANIMALS-2,954 Thoroughbred yearlings. Procedures-Records of yearlings that had endoscopic evaluation of the larynx between 1998 and 2001 were obtained, and results were graded by use of standardized scales. A modified Havemeyer scale (grade I, II.1, II.2, III, or IV) was used to evaluate AF; ES was graded on a scale of 0 to IV. Records were annotated if the epiglottis was subjectively short or narrow. Racing performance data were obtained from an online database. RESULTS-Horses with grade II.2 AF had significantly less earnings at 4 years of age, compared with earnings of horses with AF grades < II.2. Grade III AF was associated with fewer starts and less earnings at 3 and 4 years of age. No horses met the criteria for grade IV AF. Horses with ES grades > II had less earnings at 2 and 4 years of age, compared with earnings of horses with ES grades < II. A short epiglottis was associated with less earnings at 2 and 3 years of age. CONCLUSIONS AND CLINICAL RELEVANCE-Analysis suggested that yearlings with grade III AF had a decrease in athletic potential. Yearlings with grade II.2 AF, an ES grade > II, or a short epiglottis typically had decreases in racing performance. These factors should be evaluated carefully when developing purchase recommendations.

Reason for Performing Study: Endoscopy of the upper airways of horses is used as a diagnostic tool and at purchase examinations. On some occasions it is necessary to use sedation during the procedure and it is often speculated that the result of the examination might be influenced due to the muscle-relaxing properties of the most commonly used sedatives., Objectives: To evaluate the effect of detomidine (0.01 mg/kg bwt) and acepromazine (0.05 mg/kg bwt) on the appearance of symmetry of rima glottidis, ability to abduct maximally the arytenoid cartilages and the effect on recurrent laryngeal neuropathy (RLN) grade., Methods: Forty-two apparently normal horses underwent endoscopic examination of the upper airways on 3 different occasions, under the influence of 3 different treatments: no sedation (control), sedation with detomidine and sedation with acepromazine. All examinations were performed with a minimum of one week apart. The study was performed as an observer-blind cross-over study., Results: Sedation with detomidine had a significant effect on the RLN grading (OR = 2.91) and ability maximally to abduct the left arytenoid cartilages (OR = 2.91). Sedation with acepromazine resulted in OR = 2.43 for the RLN grading and OR = 2.22 for the ability to abduct maximally. The ability to abduct maximally the right arytenoid cartilage was not altered., Conclusions: Sedating apparently healthy horses with detomidine or acepromazine significantly impairs these horses' ability to abduct fully the left but not the right arytenoid cartilage. This resulted in different diagnosis with respect to RLN when comparing sedation to no sedation., Potential Relevance: Since the ability to abduct the right arytenoid cartilage fully is not altered by sedation, it is speculated that horses changing from normal to abnormal laryngeal function when sedated, might be horses in an early stage of the disease. To confirm or reject these speculations, further studies are needed. Until then sedation during endoscopy should be used with care.

Objective: To report the use of a nylon suture system (Canine Cranial Cruciate Ligament Repair System; Securos Inc Veterinary Orthopedics) as a prosthesis for equine laryngoplasty., Study Design: Experimental and prospective clinical study., Animals: Cadaver specimens (n = 5) and 7 horses with left laryngeal hemiplegia., Methods: A commercially available monofilament nylon suture system was implanted as a laryngeal prosthesis. Arytenoid cartilage abduction was achieved with a tensioning device applied to the suture prosthesis during transnasal endoscopic observation. Suture fixation was achieved with crimping clamps and a crimping device., Results: The nylon suture system was suitable as a laryngeal prosthesis for arytenoid cartilage abduction. The ratchet mechanism of the tensioning device facilitated abduction of the arytenoid cartilage and suture fixation was achieved by the crimped clamp without any loss of tension. Postoperatively, there was a slight loss of tension in 4 horses and complete loss of tension in 1 horse because of cartilage failure. After convalescence, none of the horses had abnormal respiratory noise, exercise intolerance or cough., Conclusions: A nylon suture system designed for canine cranial cruciate ligament repair was used successfully as a laryngeal prosthesis and facilitated control of the degree of arytenoid cartilage abduction during laryngoplasty., Clinical Relevance: For improved control of the degree of arytenoid cartilage abduction during laryngoplasty, use of a nylon suture system with metal crimps should be considered.

Objective: To evaluate the effects of various drugs and drug combinations conventionally used for anesthesia on arytenoid cartilage motion during laryngoscopy in normal dogs., Study Design: Experimental study., Animals: Six large breed healthy dogs with no previous history of respiratory dysfunction., Methods: Each dog was randomly assigned to a different injectable anesthetic protocol once weekly for 6 weeks, then in the 7th week all dogs were anesthetized with isoflurane. Videolaryngoscopy was performed and recorded starting immediately after induction until dogs could no longer be safely restrained for endoscopy. Video was digitized and 3 still images of maximal inspiration and expiration from the first 15 seconds (induction) and the last 15 seconds (recovery) were captured and imported into an image analysis software program. The height and area of the laryngeal ostium were measured in pixels. Normalization of the glottal gap area was performed using the formula (normalized glottal gap area (NGGA)=area in pixels/height(2)). ANOVA was performed on the NGGA of images collected at inspiration and expiration during induction and recovery. Fischer's exact test was performed when significance (P<.05) was found., Results: Within each protocol, laryngeal motion (defined as change in NGGA) at induction was not significantly different from laryngeal motion measured at recovery. Additionally, no significant differences were found in arytenoid motion immediately after induction when anesthetic protocols were compared. Arytenoid motion before recovery was significantly greater with thiopental when compared with propofol (P=.046), ketamine+diazepam (P=.0098), acepromazine+thiopental (P=.0021), and acepromazine+propofol (P=.0065). No significant difference in arytenoid motion was seen immediately after induction or before recovery when acepromazine+butorphanol+ isoflurane and thiopental were compared., Conclusion: We concluded that intravenous thiopental given to effect is the best choice for assessing laryngeal function in dogs. Dogs premedicated with acepromazine with or without opioids that require further anesthetic restraint for laryngoscopy should be anesthetized with isoflurane administered by mask., Clinical Relevance: Misdiagnosis of laryngeal paralysis during laryngoscopy can be avoided by selecting the anesthetic regimens with the least effect on arytenoid motion.

A new method for analysis of digital high-speed recordings of vocal-fold vibrations is presented. The method is based on the extraction of light-intensity time sequences from consecutive images, which in turn are Fourier transformed. The spectra thus acquired can be displayed in four different modes, each having its own benefits. When applied to the larynx, the method visualizes oscillations in the entire laryngeal area, not merely the glottal region. The method was applied to two laryngoscopic high-speed image sequences. Among these examples, covibrations in the ventricular folds and in the mucosa covering the arytenoid cartilages were found. In some cases the covibrations occurred at other frequencies than those of the glottis.