Partial laryngectomy for the management of laryngeal masses in six cats.

OBJECTIVES: Partial laryngectomy is an organ-sparing surgical procedure for the removal of laryngeal masses which has not been described in cats. The aim of this study was to report on the surgical procedure and the short- and long-term clinical outcomes of cats that underwent partial laryngectomy. METHODS: Medical records were retrospectively collected over a 4-year period in two institutions. The following data were retrieved: signalment, history, clinical signs, diagnostic test results, surgical procedure, postoperative management, complications and outcome. RESULTS: Six cats underwent partial laryngectomy. The most common clinical signs in cats with laryngeal masses were stridor (n = 4) and dyspnoea (n = 4). In all cats, a full-thickness portion of one or several laryngeal cartilages was resected, including thyroid cartilage alone (n = 2), thyroid cartilage and arytenoid (n = 2), and arytenoid cartilage and epiglottis (n = 2). The resected laryngeal masses were reported to be lymphoma (n = 3), carcinoma (n = 1), laryngeal cyst (n = 1) and inflammatory laryngeal disease (n = 1). All cats survived the surgical intervention of partial laryngectomy. Four cats showed varying degrees of respiratory distress in the short-term postoperative period. A temporary tracheostomy tube was placed in two cats. No other postoperative complications were noted in the short- or long-term. Four cats were still alive at the time of writing. These cats survived at least 252 days. CONCLUSIONS AND RELEVANCE: In a small number of cases, our results show that successful long-term outcomes after partial laryngectomy are achievable, with longer survival times than previously reported. Therefore, partial laryngectomy should be considered as a viable treatment option in cats with laryngeal masses.

Total laryngectomy in a cat with a laryngeal peripheral nerve sheath tumor.

OBJECTIVE: To report the surgical technique and outcome of total laryngectomy in a single clinical case. STUDY DESIGN: Case report. ANIMAL: A 5-year-old female spayed domestic shorthair cat. METHODS: A cat presented for acute, severe respiratory distress caused by an invasive laryngeal mass. Incisional biopsy was indicative of sarcoma. Computed tomography of head, neck, and thorax was performed revealing no evidence of metastasis. A total laryngectomy and permanent tracheostomy were performed, and the cat could breathe without difficulties immediately postoperatively. Histopathology confirmed a laryngeal low-grade peripheral nerve sheath tumor (PNST). RESULTS: Surgical margins were free of tumor cells. Surgical revision of the tracheostomy stoma due to obstructive granulation tissue was necessary 24 days after the initial surgery. Nine days after revision surgery, the cat was discharged from the hospital. No evidence of local recurrence or metastasis was detected on repeat computed tomography of the head, neck, and thorax at 6 months, nor on chest radiographs at 12 months postoperatively. At the time of writing (13 months postoperatively), the cat is still alive with a good quality of life. CONCLUSION: Total laryngectomy with permanent tracheostomy allowed the complete removal of an obstructive laryngeal PNST and provided a good quality of life in a cat. CLINICAL SIGNIFICANCE: To the authors' knowledge, this case report represents the first detailed description of the surgical procedure and clinical outcome for a total laryngectomy in a cat.

Total laryngectomy and permanent tracheostomy in six dogs.

The objective of this report is to describe the surgical technique for total laryngectomy and outcome in six dogs. Laryngeal cancer is an uncommon and challenging clinical problem. Total laryngectomy can provide local disease control but is uncommonly performed. Detailed procedural descriptions are limited and similarly limited information is available regarding patient outcome. Institutional medical records were searched for dogs treated with total laryngectomy. Six dogs were identified. The procedure resulted in postoperative quality of life similar to permanent tracheostomy alone. Surgical margin status was evaluated in five of six cases and was complete in those five. All dogs survived to discharge from the hospital. Complications were mostly related to tracheostomy occlusion or collapse which is recognized as a complication associated with permanent tracheostomy. Patient quality of life was acceptable. Local recurrence was suspected in one dog. Recurrence was not observed in the case with unknown margin status.

Management of postoperative dysphagia after prosthetic laryngoplasty or arytenoidectomy.

OBJECTIVE: To evaluate the efficacy of various treatments for dysphagia after laryngeal surgery. STUDY DESIGN: Retrospective. ANIMALS: Horses treated for dysphagia after laryngeal surgery. METHODS: Medical records of horses treated for dysphagia after prosthetic laryngoplasty (PLP) or partial arytenoidectomy (PA) were reviewed. Signalment, prior surgery, preoperative videoendoscopic diagnosis, and surgical treatments were recorded. Short- and long-term follow-up were obtained. Chi-square and logistical regression were performed to correlate independent variables and outcomes. RESULTS: Forty-four percent of horses with prior PLP and 88% of horses with prior PA had persistent resting dorsal displacement of the soft palate (DDSP). Vocal fold augmentation (VFA) as a single treatment was most commonly performed (n = 22), followed by laryngoplasty removal (LPR; n = 1). Fifteen horses received a combination of treatments: VFA (n = 15), LPR (n = 4), laryngeal tie-forward (LTF; n = 2), and esophageal release (n = 1). Short-term clinical outcomes were reported; 80% of horses treated with VFA (n = 35) had resolution of dysphagia, and 20% were improved. Among the 33 horses available to long-term follow-up, 31 (94%) returned to some level of work, and DDSP during work was reportedly resolved in 23 of 25 horses. CONCLUSION: Vocal fold augmentation resulted in resolution of symptoms relating to dysphagia in 81% of horses. Twenty percent of horses treated with LPR had sustained resolution of dysphagia. A combination of LPR, VFA, LTF was performed in 18% of horses. CLINICAL SIGNIFICANCE: Treatment options directed at altering laryngeal geometry and/or position of the larynx were successful in resolving 86% of dysphagia in horses previously regarded as very difficult to treat.

Ex vivo evaluation of arytenoid corniculectomy, compared with three other airway interventions, performed on cadaveric equine larynges with simulated recurrent laryngeal neuropathy.

OBJECTIVE: To compare laryngeal impedance, in terms of air flow and pressure, following arytenoid corniculectomy (COR) versus 3 other airway interventions (left-sided laryngoplasty with ipsilateral ventriculocordectomy [LLP], LLP combined with COR [LLPCOR], and partial arytenoidectomy [PA]) performed on cadaveric equine larynges with simulated left recurrent laryngeal neuropathy (RLN) and to determine whether relative laryngeal collapse correlated with the interventions performed. SAMPLE: 28 cadaveric equine larynges. PROCEDURES: Each larynx in states of simulated left RLN alone and with airway interventions in the order LLP, LLPCOR, COR, and PA was evaluated in a box model construct that replicated upper airway flow mechanics consistent with peak exercise in horses. Results for impedance, calculated from airflow and pressure changes, were compared between states for each larynx. Multivariable mixed-effects analysis controlling for repeated measures within larynx was performed to calculate the predicted mean impedance for each state. RESULTS: Results indicated that tracheal adapter diameter, individual larynx properties, airway intervention, and relative laryngeal collapse affected laryngeal impedance. The LLP and LLPCOR interventions had the lowest impedance, whereas the COR and PA interventions did not differ substantially from the simulated left RLN state. Residual intraclass correlation of the model was 27.6 %. CONCLUSIONS AND CLINICAL RELEVANCE: Although impedance was higher for the simulated left RLN with the COR intervention state than with the LLP intervention state, given the clinical success of PA for treating RLN in horses and the similar results for the COR and PA intervention states in the present study, the use of COR warrants further investigation. The residual interclass correlation suggested that individual laryngeal variation affected impedance and may have a clinical effect.

Partial arytenoidectomy in 14 standing horses (2013-2017).

OBJECTIVE: To report our experience with partial arytenoidectomy in sedated standing horses. STUDY DESIGN: Retrospective study. ANIMALS: Fourteen client-owned adult horses. METHODS: The medical records (2013-2017) of horses treated with unilateral partial arytenoidectomy while standing and sedated were reviewed. Demographics, endoscopic findings, previous treatments, and outcome after surgery were investigated and recorded. RESULTS: Thirteen horses had unilateral left-sided recurrent laryngeal neuropathy (RLN) and 1 horse had bilateral RLN. Five horses had a previous failed prosthetic laryngoplasty. Left-sided partial arytenoidectomy without mucosal closure was successfully completed in all horses under sedation and local anesthesia. Report of long-term outcome was obtained via telephone conversations for 12 horses, of which 9 also had an endoscopic reevaluation performed; 3 horses had granulomas at the surgical site, of which 2 eventually required a permanent tracheostomy. Nine horses returned to athletic use without respiratory noise, 2 horses returned to athletic use with noise during exercise that was reduced compared with preoperative levels, and 1 horse continued to be used as a broodmare. CONCLUSION: Partial arytenoidectomy in standing horses was achieved with adequate sedation and local anesthesia. CLINICAL SIGNIFICANCE: Partial arytenoidectomy on standing sedated horses could be considered as an alternative to eliminate the risks associated with general anesthesia.

Effect of bilateral ventriculocordectomy via ventral laryngotomy on laryngeal airway resistance in larynges of canine cadavers.

OBJECTIVE To evaluate the effect of bilateral ventriculocordectomy via ventral laryngotomy on laryngeal airway resistance (LAR) in canine cadaver larynges. SAMPLE 6 clinically normal canine cadaver larynges. PROCEDURES LAR was determined for each specimen before (baseline) and after bilateral ventriculocordectomy with the epiglottis open and closed. After ventral laryngotomy was performed, the vocal cords were sharply excised, and the incised mucosal edges were apposed with 4-0 glycomer 631 suture in a simple continuous pattern. The thyroid cartilage was apposed with 3-0 polypropylene suture in a simple continuous pattern. RESULTS With the epiglottis closed, baseline median LAR was 27.6 cm H2O/L/s (range, 21.2 to 30.6 cm H2O/L/s), which did not differ significantly from the median LAR after bilateral ventriculocordectomy (24.7 cm H2O/L/s [range, 20.6 to 27.7 cm H2O/L/s]). With the epiglottis open, baseline median LAR was 7.3 cm H2O/L/s (range, 5.4 to 7.8 cm H2O/L/s), which did not differ significantly from the median LAR after bilateral ventriculocordectomy (7.2 cm H2O/L/s [range, 6.6 to 7.6 cm H2O/L/s]). CONCLUSIONS AND CLINICAL RELEVANCE Bilateral ventriculocordectomy did not affect LAR with an open epiglottis in canine cadaver larynges. Therefore, it may not be an effective treatment for laryngeal paralysis. It also did not affect LAR with a closed epiglottis, which may indicate protection against aspiration pneumonia.

Total laryngectomy for management of chronic aspiration pneumonia in a myopathic dog.

A 5-month-old female pit bull terrier dog evaluated for ataxia, progressive regurgitation, and recurrent aspiration pneumonia had markedly elevated creatine kinase activity, non-inflammatory generalized myopathy, and severe esophageal dysmotility. A narrow-field total laryngectomy was performed. The dog is doing well 30 months after surgery, and no longer has episodes of aspiration pneumonia, despite intermittent regurgitation. This case represents the first application of total laryngectomy for the prevention of chronic recurrent aspiration pneumonia in the dog.

Laryngectomie totale pour la gestion d'une pneumonie par aspiration chronique chez un chien myopathique. Une chienne Pit Bull Terrier âgée de 5 mois évaluée pour de l'ataxie, de la régurgitation progressive et une pneumonie par aspiration récurrente présentait une activité de la créatine kinase particulièrement élevée, une myopathie généralisée non inflammatoire et un trouble de motilité de l'œsophage grave. Une laryngectomie totale à champ étroit a été réalisée. La chienne se porte bien 30 mois après la chirurgie et n'a plus d'épisodes de pneumonie par aspiration, malgré une régurgitation intermittente. Ce cas représente la première application d'une laryngectomie totale pour la prévention d'une pneumonie par aspiration chronique récurrente chez un chien.(Traduit par Isabelle Vallières).

Racing performance following prosthetic laryngoplasty using a polyurethane prosthesis combined with a laser-assisted ventriculocordectomy for treatment of recurrent laryngeal neuropathy in 78 Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: Recurrent laryngeal neuropathy (RLN) causes airway obstruction and adversely affects racing performance in Thoroughbred racehorses. Prosthetic laryngoplasty (PL) is the preferred treatment of RLN as it returns variables of airway mechanics to baseline. A number of materials have been evaluated as prostheses; however, the application of Lycra has not been rigorously investigated. OBJECTIVE: To evaluate the efficacy of PL using a Lycra prosthesis, in combination with transendoscopic, laser-assisted ventriculocordectomy, to restore racing performance in Thoroughbred racehorses with RLN. STUDY DESIGN: Retrospective case series. METHODS: Medical records, preoperative and post operative racing performance indices from 78 Thoroughbred racehorses that underwent surgical treatment for RLN were evaluated. Medical records, preoperative and post operative racing performance indices were evaluated. Case history, postoperative complications and PL failure were recorded. Racing performance was analysed using Beyer Speed Figures (BSF), earnings and a performance index (PI), with comparisons made between the 3 races before and after surgery. Factors associated with return to racing and racing performance were analysed. RESULTS: Eighty-two per cent (46/56) of horses that raced prior to surgery and 75% (15/20) of horses that had not raced prior to surgery competed in at least one race post operatively. Horses had a lower BSF and PI in the final race before surgery. Following surgery, PI and BSF values were restored to preoperative values in 73% and 78% of horses respectively. Surgical failure rate and immediate post operative complication rate were lower than, or comparable with,other reported prosthesis materials. CONCLUSIONS: Thoroughbred racehorses with RLN have a good prognosis for racing successfully after PL using a Lycra prosthesis. The described surgical technique is associated with a low post operative complication rate and an increase in indicators of racing performance (PI and BSF) post operatively. Lycra offers an attractive option for application as a prosthetic for PL with a low complication rate and similar efficacy to reported rigid prostheses.

Changes in rima glottidis area and lack of laryngeal epiglottic-glottic seal after unilateral cricoarytenoid lateralization ex vivo.

OBJECTIVE: To evaluate variation in rima glottidis (RG) area and lack of epiglottic-glottic seal (LEGS) of the canine larynx associated with different suture anchor points in the arytenoid and cricoid cartilages, dissection of the cricoarytenoid joint capsule, section of the interarytenoid band, and disarticulation of the cricothyroid joint. STUDY DESIGN: Experimental study. ANIMALS: Cadaveric canine larynges (n = 18). METHODS: Larynges were assigned to 2 groups: group 1 = intact cricothyroid articulation and group 2 = cricothyroid articulation sharply sectioned. In each group, the arytenoid cartilage was lateralized successively as follows: (a) intact cricoarytenoid articulation, (b) cricoarytenoid articulation sharply sectioned, and (c) division of the interarytenoid band. Each variation was performed initially with the suture passed dorsally into the cricoid cartilage then with the suture passed laterally. Each time, the increase of rima glottis area (%) and the LEGS (mm(2) ) were measured. RESULTS: Rima glottis area (RGA): when the suture was placed dorsally, division of the interarytenoid band resulted in a significant increase in RGA compared with groups with an intact band. Laryngeal distortion: when the suture through the cricoid cartilage was dorsal, LEGS increased with section of the cricothyroid articulation, dissection of cricoarytenoid articulation, and division of the interarytenoid band. CONCLUSION: Unilateral arytenoid lateralization results in some degree of LEGS with a misalignment of the epiglottis over the RG. Our results revealed that the optimal RGA associated with the minimal LEGS was obtained with dorsal placement of a cricoarytenoid suture when the cricothyroid joint and the interarytenoid band were intact.

Outcome of 45 dogs with laryngeal paralysis treated by unilateral arytenoid lateralization or bilateral ventriculocordectomy.

The purpose of this retrospective study was to assess risk factors and complications affecting postoperative outcome of dogs with laryngeal paralysis treated by either unilateral arytenoid lateralization (UAL) or bilateral ventriculocordectomy (VCC). Medical records of all dogs having either UAL or VCC between 2000 and 2011 were analyzed. Twenty-five dogs had VCC and 20 dogs had UAL. The overall postoperative complications rates for VCC and UAL were similar (52% and 60%, respectively; P = .0887). Dogs that had UAL were more likely to have acute postoperative respiratory distress and aspiration pneumonia (P = .0526). Dogs with VCC were more likely to have chronic postoperative respiratory distress and aspiration pneumonia (P = .0079). Revision surgery was required in 6 dogs (24%) following VCC and 2 dogs (10%) following UAL. Sex, breed, presenting complaint, type of service provided, and concurrent diseases were not significantly associated with higher risk of either death or decreased survival time postoperatively with either procedure. Overall postoperative complication rates, required revision surgeries, and episodes of aspiration pneumonia were similar in dogs undergoing UAL and VCC surgeries. Dogs that had VCC appeared to have an increased risk of lifelong complications postoperatively compared with UAL; therefore, VCC may not be the optimal choice for treatment of laryngeal paralysis.

Bilateral ventriculocordectomy via ventral laryngotomy for idiopathic laryngeal paralysis in 88 dogs.

Bilateral ventriculocordectomy through a ventral median laryngotomy was performed for the treatment of idiopathic laryngeal paralysis in 88 dogs. The purpose of this retrospective analysis was to provide long-term follow-up for a large number of dogs surgically managed with this technique. A combination of medical record and completed client questionnaire information provided short-term (14 days) follow-up for 88 dogs and long-term (>6 mo) follow-up for 42 dogs. Major short-term postoperative complications were identified in 3 of 88 (3.4%) patients. Major long-term complications were identified in 3 of 42 (7.1%) patients. The results of surgery were considered to be very satisfactory in 93% and unsatisfactory in 7%. Three dogs in this series developed aspiration pneumonia. Bilateral ventriculocordectomy through a ventral median laryngotomy is associated with a low incidence of both short- and long-term complications. Due to the ease of this procedure, the minimal surgical trauma to the patient, and the satisfactory results, this surgery should be considered an option for the treatment of idiopathic laryngeal paralysis in the dog.

Complications of upper airway surgery in companion animals.

Surgery of the upper airway is performed in dogs for the correction of brachycephalic airway syndrome and laryngeal paralysis and for temporary or permanent tracheostomy. Although technically simple to perform, upper airway surgeries can lead to the development of significant postoperative complications. This article reviews complications associated with common surgical conditions of the upper airway. It involves a discussion of brachycephalic airway syndrome and associated respiratory and gastrointestinal complications. It also covers laryngeal paralysis with a focus on unilateral arytenoid lateralization and the complication of aspiration pneumonia. The condition of acquired laryngeal webbing/stenosis and potential treatment options is also discussed. Finally, tracheostomies and associated complications in dogs and cats are reviewed.

Considerations for pacing of the cricoarytenoid dorsalis muscle by neuroprosthesis in horses.

REASONS FOR PERFORMING STUDY: The success rate of prosthetic laryngoplasty is limited and may be associated with significant sequelae. Nerve muscle pedicle transplantation has been attempted but requires a year before function is restored. OBJECTIVE: To determine the optimal parameters for functional electrical stimulation of the recurrent laryngeal nerve in horses. METHODS: An experimental in vivo study was performed on 7 mature horses (2-21 years). A nerve cuff was placed on the distal end of the common trunk of the recurrent laryngeal nerve (RLN). In 6 horses the ipsilateral adductor branch of RLN was also transected. The electrodes were connected to programmable internal stimulator. Stimulation was performed using cathodic phase and then biphasic pulses at 24 Hz with a 0.427 ms pulse duration. Stimulation-response experiments were performed at monthly intervals, from one week following implantation. The study continued until unit failure or the end of project (12 months). Two of the horses were stimulated continuously for 60 min to assess onset of fatigue. RESULTS: Excellent arytenoid cartilage abduction (mean arytenoid angle of 52.7 degrees, range 48.5-56.2 degrees) was obtained in 6 horses (laryngeal grades I or II (n = 3) and III (n = 2). Poor abduction was obtained in grade IV horses (n = 2). Arytenoid abduction was maintained for up to a year in one horse. Technical implant failure resulted in loss of abduction in 6 horses at one week to 11 months post operatively. Mean tissue impedance was 1.06 kOhm (range 0.64-1.67 kOhm) at one week, twice this value at 2 months (mean 2.32, range 1.11-3.75 kOhm) and was stable thereafter. Maximal abduction was achieved at a stimulation range of 0.65-7.2 mA. No electrical leakage was observed. Constant stimulation of the recurrent laryngeal nerve for 60 min led to full abduction without evidence of muscle fatigue. CONCLUSIONS: Functional electrical stimulation of the recurrent laryngeal nerve leading to full arytenoid abduction can be achieved. The minimal stimulation amplitude for maximal abduction angle is slightly higher than those for man and dogs. CLINICAL RELEVANCE: This treatment modality could eventually be applicable to horses with recurrent laryngeal neuropathy.

Postoperative race performance is not correlated with degree of surgical abduction after laryngoplasty in National Hunt Thoroughbred racehorses.

OBJECTIVES: To (1) assess the degree of arytenoid cartilage abduction lost after laryngoplasty (LP) in Thoroughbred National Hunt racehorses and (2) to correlate postoperative racing performance with degree of arytenoid abduction after LP. STUDY DESIGN: Case series. ANIMALS: National Hunt Thoroughbred racehorses (n=68). METHODS: Grade of postoperative arytenoid abduction for National Hunt racehorses that had LP with ventriculocordectomy was assessed at 1 day, 6 days, and 6 weeks after LP. Race records were analyzed to ascertain if there was correlation between the degree of arytenoid cartilage abduction and various measures of race performance (return to racing postoperatively, total earnings in 5 races immediately postoperatively, and lifetime number of starts postoperatively). RESULTS: Median postoperative arytenoid abduction was grade 2 on day 1 but had decreased to grade 3 by 6 weeks. Horses with grades 1, 2, and 3 abduction 1 day after surgery had median losses of 1, 1, and 0.5 abduction grades, respectively, at 6 weeks. Horses with grade 1 abduction on day 1 were significantly more likely to lose abduction by day 6 after surgery than horses with grade 3 abduction on day 1. There was no statistically significant correlation between the postoperative grade of arytenoid abduction at any time point and earnings in 5 races after surgery, likelihood of racing postoperatively, or total number of lifetime race starts postoperatively. CONCLUSIONS: Horses with maximal (grade 1) surgical arytenoid abduction are significantly more likely to suffer postoperative loss of abduction than those with grade 3 abduction. Postoperative grade of abduction does not appear significantly correlated with markers of racing performance in National Hunt racehorses; however, very few horses with poor (grade 4 or 5) abduction were included and thus conclusions regarding racing performance in such horses cannot be drawn from this study. CLINICAL RELEVANCE: Seemingly, most horses with grade 3 laryngeal abduction can race successfully and perhaps surgeons should not be disillusioned by the appearance of only moderate (grade 3) abduction in the long term after LP in racehorses.

Race performance after laryngoplasty and ventriculocordectomy in National Hunt racehorses.

OBJECTIVE: To evaluate the effect of laryngoplasty (LP) on race performance in longer distance (National Hunt) Thoroughbred racehorses. STUDY DESIGN: Case-control study. ANIMALS: National Hunt Thoroughbred racehorses (n=71) and race-matched controls (n=126). METHODS: Race records for National Hunt racehorses that had LP and ventriculocordectomy were analyzed and racing performance was compared with race-matched controls. RESULTS: Sixty-three of 71 cases were matched with controls. Postoperatively, 78% of cases raced, 47% improved their individual performance and cases were as likely to start in 1 or 3 races as controls. In the 5 preoperative races, case horses earned less prize money than race-matched controls but there was no difference in prize money earned in 5 postoperative races between groups. Cases started in significantly fewer total (lifetime) races both before and after the date of surgery compared with controls. CONCLUSIONS: LP seemingly restored short-term postoperative racing performance of National Hunt horses to a level comparable with that of a matched control population; however, the career "longevity" of case horses appears to be shorter than that of control horses. CLINICAL RELEVANCE: LP appears to be a suitable treatment for recurrent laryngeal neuropathy in National Hunt racehorses.

Subtotal or partial unilateral arytenoidectomy for treatment of arytenoid chondritis in five calves.

CASE DESCRIPTION: 5 calves were evaluated for abnormal respiratory noise associated with variable degrees of respiratory distress. CLINICAL FINDINGS: Tachypnea and inspiratory dyspnea were detected at initial evaluation in all calves. Endoscopic evaluation of the upper respiratory tract revealed enlarged and immobile arytenoids. Radiographic (n = 3) and computed tomographic (1) evaluation of the laryngeal area revealed images that were indicative of a large soft tissue mass at the level of the arytenoids obstructing the rima glottis. A presumptive diagnosis of arytenoid chondritis was made. TREATMENT AND OUTCOME: A tracheostomy tube was placed in all calves. Medical treatment (with antimicrobials and anti-inflammatory drugs) was attempted in 4 calves after initial evaluation. Unilateral arytenoidectomy via a laryngotomy was performed under general anesthesia in all calves. Dysphagia and coughing were the most frequent postoperative complications. Three calves survived at least 6 months after the procedure. One calf died of a perforated abomasal ulcer 3 months after the surgery. Another calf died suddenly 1 month after the surgery of an undetermined cause. CLINICAL RELEVANCE: Unilateral arytenoidectomy was a viable surgical treatment for arytenoid chondritis in calves. Further research in a larger number of affected cattle is needed to determine the advantages or disadvantages of this procedure over other surgical techniques.

Racing performance after combined prosthetic laryngoplasty and ipsilateral ventriculocordectomy or partial arytenoidectomy: 135 Thoroughbred racehorses competing at less than 2400 m (1997-2007).

REASONS FOR PERFORMING STUDY: The success of combined prosthetic laryngoplasty with ipsilateral ventriculocordectomy (LPVC) has not been compared to that of partial arytenoidectomy (PA) in a clinical population. HYPOTHESES: In Thoroughbred (TB) racehorses: (1) earnings after LPVC are unaffected by the severity of recurrent laryngeal neuropathy (RLN) (laryngeal grade III vs. grade IV); (2) LPVC and PA yield similar results in the treatment of grade III RLN; (3) performance outcome following PA is independent of diagnosis (RLN vs. unilateral arytenoid chondritis [UAC]); and (4) neither LPVC nor PA returns horses to the level of performance of controls. METHODS: Medical and racing records of 135 TB racehorses undergoing LPVC or PA for the treatment of grade III or IV RLN or UAC were reviewed. Racing records of age and sex matched controls were also reviewed. RESULTS: After LPVC, horses with grade III RLN performed better compared to those with grade IV RLN. Furthermore, horses treated for grade III RLN by LPVC showed post operative earnings comparable to controls. Rate of return to racing were similar for PA and LPVC, although LPVC resulted in higher post operative earnings. Performance after PA was similar regardless of diagnosis (UAC or RLN). Finally, neither LPVC when performed for grade IV RLN, nor PA performed for either diagnosis restored post operative earnings to control levels. CONCLUSIONS: Thoroughbred racehorses treated by LPVC for grade III RLN show significantly better post operative earnings compared to horses treated for grade IV disease. In grade III RLN, LPVC returns earning potential to control levels. PA and LPVC lead to similar success in terms of rate of return to racing, but PA leads to inferior earnings after surgery. POTENTIAL RELEVANCE: Laryngoplasty should be recommended for all TB racehorses with grade III RLN to maximise return to racing at a high level. This contradicts the common approach of waiting for complete paralysis.

Intra-articular stabilisation of the equine cricoarytenoid joint.

REASONS FOR PERFORMING STUDY: The success of laryngoplasty is limited by abduction loss in the early post operative period. OBJECTIVE: To determine the efficacy of polymethylmethacrylate (PMMA) in stabilising the cricoarytenoid joint (CAJ) and reducing the force on the laryngoplasty suture. HYPOTHESIS: Injection into the cricoarytenoid joint resists the forces produced by physiological laryngeal air flows and pressures thereby reducing the force experienced by the laryngoplasty suture. METHODS: Ten cadaver larynges were collected at necropsy and PMMA was injected into one CAJ at selected random. Each larynx was subjected to physiological conditions with with constant (static) or cycling (dynamic) flow. The specimens were tested sequentially in each of 4 conditions: 1) bilateral full abduction (Control 1); 2) transection of the suture on the side without PMMA; 3) bilateral abduction achieved by replacing the suture (Control 2); and 4) cutting the suture on the PMMA side. Tracheal pressure and flow and pressure in the flow chamber were recorded using pressure and flow transducers. The strain experienced by each suture during bilateral abduction (Controls 1 and 2) was measured. Statistical comparison of the 4 conditions was performed using a mixed effect model with Tukey's post hoc test for multiple comparisons. The strain gauge data were analysed by paired comparison of the regression slopes. RESULTS: In the static and dynamic states, tracheal pressure increased and tracheal flow decreased when the suture on the non-cement side was cut (P < 0.05). There was no significant difference in any outcome measure between PMMA injected into the CAJ and bilaterally abducted specimens (Controls 1 and 2) for either condition. The rate of increase in strain with increasing translaryngeal pressure was significantly less on the suture with PMMA placed in the CAJ (P = 0.03). CONCLUSIONS: These data provide strong evidence that injecting PMMA into the CAJ resists the collapsing effect of physiological airflows and pressures in vitro and reduces the force experienced by the laryngoplasty suture during maximal abduction. POTENTIAL RELEVANCE: Augmentation of prosthetic laryngoplasty with this technique may reduce arytenoid abduction loss in the early post operative period.

Long-term study of partial arytenoidectomy with primary mucosal closure in 76 Thoroughbred racehorses (1992-2006).

REASON FOR PERFORMING STUDY: The effectiveness and best method to perform a partial arytenoidectomy in racehorses is unclear. This study was performed to evaluate the success of and complications that can occur after a unilateral partial arytenoidectomy with primary mucosal closure in Thoroughbred racehorses. HYPOTHESIS: Partial arytenoidectomy is an effective surgical procedure to return Thoroughbred racehorses, afflicted by arytenoid chondropathy or a failed laryngoplasty, to preoperative levels of performance. METHODS: Seventy-six Thoroughbred racehorses admitted to the New Bolton Centre between 1992 and 2006 were assessed. Information was obtained from the medical records about the horse, laryngeal abnormalities, surgery and other findings during hospitalisation. Racing information was evaluated relative to those independent variables by an analysis of variance with a level of significance of P<0.05. RESULTS: Arytenoid chondropathy was the presenting complaint in 54 horses and failed laryngoplasty in 22 horses. Thirteen horses (17%) underwent a second surgery for laser excision of intralaryngeal granulation tissue at the arytenoidectomy site. Seventy-three horses were discharged from the hospital and racing outcome was evaluated. Sixty horses (82%) raced after surgery and 46 horses (63%) raced 5 or more times after surgery. The median time from surgery to the first start was 6 months. The average earnings/start was not significantly different before and after surgery. There was no association between earnings after surgery and age, gender, location of lesion, type of lesion, duration of tracheal intubation or undergoing a second surgery. CONCLUSIONS AND POTENTIAL RELEVANCE: A Thoroughbred racehorse is likely to race after a unilateral partial arytenoidectomy with primary mucosal closure and return to a preoperative level of performance.