Transendoscopic, laser-assisted ventriculocordectomy for treatment of left laryngeal hemiplegia in horses: 22 cases (1999-2005)

OBJECTIVE: To determine long-term effects of transendoscopic, laser-assisted ventriculocordectomy (LAVC) on airway noise and performance in horses with naturally occurring left laryngeal hemiplegia. DESIGN: Retrospective case series. ANIMALS: 22 horses with left laryngeal hemiplegia treated by means of LAVC. PROCEDURES: Medical records were reviewed and initial complaint, intended use of the horse, duration of abnormal airway noise, preoperative performance level, endoscopic findings, surgical procedure, postoperative treatment, and complications were recorded. Follow-up telephone interviews with owners and trainers were conducted to determine time for return to intended use, level of postoperative performance, and percentage reduction in airway noise. RESULTS: All horses were examined because of excessive airway noise; 10 (45%) had concurrent exercise intolerance. Left ventriculocordectomy was performed in all 22 horses; bilateral ventriculocordectomy (right ventriculocordectomy was done 1 year later) was performed in 1 horse (5%). Complications occurred in 3 (14%) horses. Twenty (91%) horses returned to their intended use. Excessive airway noise was eliminated after surgery in 18 (82%) horses; exercise intolerance improved postoperatively in 8 of 10 horses. Three racing Thoroughbreds returned to racing; 1 additional racehorse returned to racing but required a laryngoplasty 1 year later to continue racing. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that LAVC was an effective procedure for elimination of excessive airway noise and improvement of performance in horses with left laryngeal hemiplegia.     

Histological evaluation of the equine larynx after unilateral laser-assisted ventriculocordectomy

REASONS FOR PERFORMING STUDY: Trans-endoscopic laser surgery, such as unilateral laser-assisted ventriculocordectomy (LVC), has gained popularity in the treatment of RLN because a laryngotomy incision or general anaesthesia are not required. However, removal of the vocal fold and ventricle takes considerable laser energy and could cause collateral tissue damage, including injury to the adjacent laryngeal cartilages. OBJECTIVES: To document the histological effects of laser surgery on laryngeal tissues in horses that have undergone LVC for the treatment of laryngeal hemiplegia (LH). METHODS: Six horses were used: 4 with experimentally induced LH that had subsequently undergone LVC 6 months prior to euthanasia; and, 2 horses were used as controls. One of the control horses with naturally occurring LH was used to study the effect of neuropathy alone, whereas the other was subjected to euthanasia immediately following LVC to evaluate the acute effect of laser surgery. Using a band saw, each larynx was sectioned transversely at 5 mm intervals and evaluated histologically. RESULTS: Acutely, LVC caused thermal damage to adjacent soft tissues but did not affect the histology of the laryngeal cartilages. Six months after LVC, laryngeal cartilages were histologically normal and there was squamous metaplasia of the repaired laryngeal mucosa, resulting in restitution of the mucosal integrity. CONCLUSIONS: Using a diode laser in contact fashion at 20 W, LVC can be used to remove the laryngeal vocal fold and ventricle without causing laryngeal cartilage damage. POTENTIAL RELEVANCE: Laryngeal chondritis is an unlikely consequence of LVC.     

Electromyographic evaluation of horses with laryngeal hemiplegia

Thirty-eight horses suspected of having laryngeal hemiplegia had electromyograms (EMGs) performed on the dorsal cricoarytenoid muscle (DCAM). Electromyographic abnormalities consisted of fibrillation potentials, positive sharp waves, bizarre high frequency discharges, and reduced insertional activity. Normal motor activity consisted of motor unit activity during inspiration, or less frequently motor unit activity during inspiration with subsequent tonic motor activity. In affected muscles, motor unit activity was often absent but when present there was activity consisting of motor units which did not correspond to a particular phase of respiration or it was consistent with normal motor unit activity.     

Ventriculocordectomy reduces respiratory noise in horses with laryngeal hemiplegia

REASONS FOR PERFORMING STUDY: Show and performance horse with laryngeal hemiplegia (LH) often present for excessive respiratory noise rather than significant exercise intolerance. Therefore, the goal of surgery in these horses is to reduce respiratory noise but there are no quantitative studies evaluating the effect of any upper-airway surgery in LH-affected horses. OBJECTIVE: To determine whether bilateral ventriculocordectomy (VC) reduces respiratory noise in exercising horses with laryngeal hemiplegia. METHODS: Six Standardbred horses with normal upper airways were used in this study. Respiratory sounds and inspiratory trans-upper airway pressure (Pui) were measured in all horses before and after induction of LH, and 30, 90 and 120 days after VC. In horses with LH, spectrogram analysis revealed 3 inspiratory sound formants centred at approximately 400, 1700 and 3700 Hz. Inspiratory sound levels (SL) and the sound intensity of the 3 inspiratory formants (F1, F2, F3 respectively) were measured using a computer-based sound analysis programme. RESULTS: In LH-affected horses, Pui, inspiratory SL and the sound intensity of F2 and F3 were significantly increased compared to baseline values. At 90 and 120 days after VC the sound intensities of F2 and F3 returned to baseline values. The Pui and SL, were significantly decreased compared to LH values, but remained different from baseline. CONCLUSIONS: VC effectively reduces inspiratory noise in LH-affected horses by 90 days following surgery. Inspiratory trans-upper airway pressures are improved 30 days following VC, but do not return to baseline values. POTENTIAL RELEVANCE: VC can be recommended as a surgical treatment of LH-affected horses if reduction of respiratory noise is the primary objective of surgery. Further studies are required to determine if variations of the surgical technique used in this study will have similar results.     

Effect of ventriculectomy versus ventriculocordectomy on upper airway noise in draught horses with recurrent laryngeal neuropathy

Reasons for performing study: Little is known about the efficacy of bilateral ventriculectomy (VE) or bilateral ventriculocordectomy (VCE) in draught horses. Objectives: To compare the effect of VE and VCE on upper airway noise in draught horses with recurrent laryngeal neuropathy (RLN) by use of quantitative sound analysis techniques. Hypothesis: In competitive draught horses with grade 4 RLN, VE and VCE reduce upper airway noise during exercise, but VCE is more effective. Methods: Thirty competitive hitch or pulling draught horses with grade 4 RLN were evaluated for upper airway sound during exercise. Respiratory rate (RR), inspiratory (Ti) and expiratory time (Te), the ratio between Ti and Te (Ti/Te), inspiratory (Sli) and expiratory sound levels (Sle), the ratio between Sli and Sle (Sli/Sle), and peak sound intensity of the second formant (F2) were calculated. Eleven horses were treated with VE and 19 with VCE. After 90 days of voice and physical rest and 30 days of work, the horses returned for post operative upper airway sound evaluation and resting videoendoscopy. Results: VE significantly reduced Ti/Te, Sli, Sli/Sle and the sound intensity of F2. Respiratory rate, Ti, Te and Sle were unaffected by VE. VCE significantly reduced Ti/Te, Ti, Te, Sli, Sli/Sle and the sound intensity of F2, while RR and Sle were unaffected. The reduction in sound intensity of F2 following VCE was significantly greater than following VE. After VE and VCE, 7/11 (64%) and 15/18 (83%) owners, respectively, concluded that the surgery improved upper airway sound in their horses sufficiently for successful competition. Conclusions: VE and VCE significantly reduce upper airway noise and indices of airway obstruction in draught horses with RLN, but VCE is more effective than VE. The procedures have few post operative complications. Potential relevance: VCE is recommended as the preferred treatment for RLN in draught horses. Further studies are required to evaluate the longevity of the procedure's results.     

The effect of recurrent laryngeal neurectomy in conjunction with laryngoplasty and unilateral ventriculocordectomy in thoroughbred racehorses

OBJECTIVE: To investigate the effects of recurrent laryngeal neurectomy (RLN) in combination with laryngoplasty and ventriculocordectomy on the postoperative performance of Thoroughbred racehorses treated for grade III left laryngeal hemiparesis (LLH). STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Fifty-five Thoroughbred racehorses. METHODS: Medical records for Thoroughbred racehorses treated surgically by laryngoplasty and laser ventriculocordectomy with or without RLN between June 1993 and December 1996 were reviewed. Outcome was evaluated subjectively by assessment of performance obtained from telephone interviews with owners and trainers, and objectively by assessment of racing performance for 3 races before and after surgery using a performance index (PI). RESULTS: Fifty-five Thoroughbred racehorses with resting endoscopic grade III LLH were treated by laryngoplasty and ventriculocordectomy either with (39 horses) or without (16 horses) RLN. For RLN horses, respondents for 38 horses believed performance was improved in 19 horses, unchanged in 16 horses, and decreased in 3 horses. For horses without RLN, respondents for 9 horses reported that performance was improved in 5 horses, unchanged in 2 horses, and decreased in 2 horses. PI scores were improved in 18 RLN horses and in 6 horses without RLN; there was no statistical difference in outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Use of RLN in combination with laryngoplasty and ventriculocordectomy for treatment of grade III LLH may not improve postoperative racing performance.     

Effect of laryngoplasty on respiratory noise reduction in horses with laryngeal hemiplegia

REASONS FOR PERFORMING STUDY: Laryngoplasty is the technique of choice for treatment of laryngeal hemiplegia, with the aim of improving airway function and/or eliminating respiratory noise. However, there are no quantitative data in the literature describing the effect of laryngoplasty on upper airway noise or its relationship to upper airway mechanics in horses with laryngeal hemiplegia. OBJECTIVES: To determine whether laryngoplasty reduces respiratory noise in exercising horses with laryngeal hemiplegia; and to establish whether the degree of upper airway obstruction can be predicted by upper airway noise, or the degree of arytenoid abduction correlated with airway obstruction and noise production. METHODS: Six Standardbred horses with normal upper airways during maximal exercise were used. Respiratory sounds and inspiratory transupper airway pressure (Pui) were measured in all horses before and after induction of laryngeal hemiplegia and 30, 60 and 90 days after laryngoplasty. Inspiratory sound level (SL) and the sound intensity of the 3 inspiratory formants (F1, F2 and F3, respectively) were measured using a computer-based sound analysis programme. The degree of abduction was graded by endoscopic visualisation 1, 30, 60 and 90 days post operatively. Linear regression analysis was used to determine correlations between Pui, sound indices and grades of arytenoid abduction. RESULTS: In laryngeal hemiplegia-affected horses, Pui, inspiratory SL and the sound intensity of F1, F2 and F3 were significantly increased. At 30 days following laryngoplasty, the sound intensity of F1 and Pui returned to baseline values. The sound intensities of F2, F3 and SL were significantly improved from laryngeal hemiplegia values at 30 days post operatively, but did not return to baseline at any measurement period. Sound level, F2 and F3 were significantly correlated with Pui (P<0.05), but the correlations were weak (r2 = 0.26, 035 and 0.40, respectively). Grade of abduction and F2 were positively and significantly correlated (P<0.006, r2 = 0.76). Grade of arytenoid abduction and Pui were not correlated (P = 0.12). CONCLUSIONS: Laryngoplasty reduced inspiratory noise in laryngeal hemiplegia-affected horses by 30 days following surgery, but did not return it to baseline values. While upper airway noise and Pui were correlated, this relationship was insufficiently strong to predict Pui from noise in individual animals. The degree of arytenoid abduction was not correlated with Pui, but was positively correlated with noise production. POTENTIAL RELEVANCE: Laryngoplasty reduces upper airway noise in horses with laryngeal hemiplegia, but is not as effective as bilateral ventriculocordectomy in this regard, although respiratory noise reduction occurs more rapidly than with bilateral ventriculocordectomy. Residual noise during exercise cannot be used as a predictor of improvement in upper airway function in individual horses following laryngoplasty. The degree of arytenoid abduction obtained following surgery does not affect upper airway flow mechanics. Interestingly, we found that the greater the arytenoid abduction, the louder the respiratory noise.     

Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia

OBJECTIVE: To report the effect of unilateral laser vocal cordectomy on respiratory noise and airway function in horses with experimentally induced laryngeal hemiplegia (LH). STUDY DESIGN: Experimental study. ANIMALS: Six Standardbred horses without upper airway abnormalities at rest or during high-speed treadmill exercise. METHODS: Respiratory sounds and inspiratory trans-upper airway pressure (P(Ui)) were measured before (baseline) and 14 days after induction of LH by left recurrent laryngeal neurectomy, and again 30, 60, 90, and 120 days after endoscopically assisted laser cordectomy of the left vocal cord. Data were collected with the horses exercising on a treadmill at a speed producing maximum heart rate (HR(max)). RESULTS: In horses exercising at HR(max), induction of LH caused a significant increase in P(Ui), sound level (SL), and the sound intensity of formant 2 (F(2)) and 3 (F(3)). The sound intensity of formant 1 (F(1)) was unaffected by induction of LH. Laser vocal cordectomy had no effect on SL, or on the sound intensity of F(1) and F(3). At 30, 60, 90, and 120 days after surgery, P(Ui) and the sound intensity of F(2) were significantly reduced, but these variables remained significantly different from baseline values. CONCLUSIONS: Unilateral laser vocal cordectomy did not effectively improve upper airway noise in horses with LH. The procedure decreased upper airway obstruction to the same degree as bilateral ventriculocordectomy. CLINICAL RELEVANCE: Currently, laser vocal cordectomy cannot be recommended for the treatment of upper airway noise in horses with LH.     

Effects of ventriculectomy, prosthetic laryngoplasty, and exercise on upper airway function in horses with induced left laryngeal hemiplegia

Effects of ventriculectomy and prosthetic laryngoplasty on upper airway flow mechanics and blood gas tensions in exercising horses with induced left laryngeal hemiplegia were assessed. Five adult horses were trained to stand, trot (4.5 m/s), and gallop (7.2 m/s) on a treadmill (6.38 degrees incline). Inspiratory and expiratory airflows (VImax, VEmax, respectively) were measured using a 15.2-cm diameter pneumotachograph in a face mask. Inspiratory and expiratory transupper airway pressures (PuI, PuE, respectively) were determined as pressure differences between barometric pressure and lateral tracheal pressure. Blood collected from exteriorized carotid arteries was analyzed for PaO2, PaCO2, pH, hemoglobin (Hb) content, and HCO3- values. Heart rate (HR) was determined with an HR monitor. Measurements were made with horses standing, trotting, and galloping before left recurrent laryngeal neurectomy (LRLN; base line), 14 days after LRLN, 30 days after ventriculectomy (44 days after LRLN), and 14 days after prosthetic laryngoplasty (58 days after LRLN). Before LRLN (base line), increasing treadmill speed for horses from standing to the trot and gallop progressively increased HR, respiratory frequency, VImax, VEmax, PuI, PuE, Hb, and PaCO2 values and decreased PaO2, pH, and HCO3- values; inspiratory and expiratory impedances were unchanged. After LRLN, inspiratory impedance and PuI were significantly (P less than 0.05) increased in horses at the trot and gallop, and PaCO2 was significantly increased in horses at the gallop. The VImax and respiratory frequency were significantly (P less than 0.05) decreased in horses at the gallop. Left recurrent laryngeal neurectomy had no effect on PuE, VEmax, HR, PaO2, pH, Hb, or expiratory impedance values.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of laryngeal hemiplegia and laryngoplasty on airway flow mechanics in exercising horses

The effect of left laryngeal hemiplegia on airway flow mechanics in 5 exercising horses was examined, and the efficacy of surgical repair by prosthetic laryngoplasty was evaluated. Measurements of the upper airway flow mechanics were made with horses on a treadmill (incline 6.38 degrees) while standing (period A); walking at 1.3 m/s (period B); trotting at 2.6 m/s (period C); trotting at 4.3 m/s (period D); and standing after exercise (period E). Experiments were done on healthy horses before any surgical manipulation (control), at 10 days after left recurrent laryngeal neurectomy, and at least 14 days after prosthetic larynogoplasty. Increasing treadmill speed from period A to period D progressively increased heart rate, respiratory frequency, peak inspiratory flow, and peak expiratory flow, but inspiratory resistance and expiratory resistance remained unchanged. Neither left recurrent laryngeal neutrectomy nor prosthetic laryngoplasty affected heart rate, respiratory frequency, peak expiratory flow, or expiratory resistance when compared with those values at the control measurement periods. Left recurrent laryngeal neurectomy resulted in inspiratory flow limitation at peak inspiratory flow of approximately 25 L/s, and increased inspiratory resistance at periods D and E. Subsequent prosthetic laryngoplasty alleviated the flow limitation and reduced inspiratory resistance at measurement periods D and E.     

Comparison of unilateral arytenoid lateralization and ventral ventriculocordectomy for the treatment of experimentally induced laryngeal paralysis in dogs.

This study evaluated changes in respiratory function in dogs with experimentally induced laryngeal paralysis treated with either unilateral arytenoid lateralization or ventral ventriculocordectomy, and compared the effectiveness of these procedures. Evaluation consisted of clinical assessment and tidal breathing flow volume loop and upper airway resistance measurements. Carbon dioxide and doxapram hydrochloride were used as respiratory stimulants. Initially, all dogs improved clinically after corrective surgery. However, by the end of the study, laryngeal collapse had developed in 2 of 5 dogs corrected by ventral ventriculocordectomy. No statistical differences in upper airway mechanics testing were seen between the surgical procedures. With both groups combined, many measurements of upper airway obstruction improved after surgical correction. Based on this study, these surgical procedures yield comparable results, although additional studies are needed to evaluate both the cause of laryngeal collapse and the role of upper airway mechanics testing in the evaluation of canine laryngeal paralysis.     

Treatment of laryngeal hemiplegia in horses by prosthetic laryngoplasty, ventriculectomy and vocal cordectomy

The medical records of 80 horses treated for left laryngeal hemiplegia by prosthetic laryngoplasty, ventriculectomy and vocal cordectomy were examined, first to compare the subjective and objective success rates for groups of horses of different ages and used for different purposes, and secondly, to compare the efficacy of including vocal cordectomy in the surgical protocol with published success rates for laryngoplasty and ventriculectomy alone. Subjectively, 70 per cent of the horses were said to have had a successful surgical outcome. The success rate for thoroughbred racehorses (66 per cent) was lower than for other breeds (90 per cent) on the basis of a subjective assessment by owners and trainers. Thoroughbreds two years old or younger had a success rate of 69 per cent, but older thoroughbreds had a success rate of 61 per cent. Of the 17 horses for which an objective performance index could be calculated, 10 (59 per cent) had an improved performance postoperatively. There was a nearly significant association between the objective and subjective assessments (P=0.078). Six of 69 horses (8.7 per cent) continued to make a respiratory noise after surgery. The subjective assessment of success did not appear to correlate with the objective measure of success used in this study and age had no apparent association with a successful surgical outcome. Inclusion of a vocal cordectomy in the surgical protocol may be more important in the eradication of postoperative respiratory noise than in improving clinical success rates.     

Neodymium:yttrium aluminum garnet laser ventriculocordectomy in standing horses

OBJECTIVE: To develop a technique for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser ventriculocordectomy in standing horses and document healing in horses undergoing laser ventriculocordectomy. ANIMALS: 6 horses between 2 and 32 years old. PROCEDURE: Under endoscopic guidance, the left laryngeal ventricle was everted with grasping forceps and excised with an Nd:YAG laser, using 60 watts of power in a noncontact fashion (6,403 to 9,197 Joules). Following removal of the ventricle, the vocal cord was photoablated. Horses were examined endoscopically 2, 7, 14, 21, 30, and 47 days after ventriculocordectomy, and 1 horse was euthanatized on each of these days. At necropsy, the larynx was removed intact and examined grossly. Samples were collected for histologic examination of the ventriculocordectomy site. RESULTS: Endoscopic examination revealed granulation tissue by day 7, the start of epithelialization by day 21, and healing by day 47. At necropsy, 4 horses were found to have a small amount of ventricular mucosa remaining dorsally and 1 additional horse was found to have a mucocele. Granulation tissue was identified grossly and histologically in the horses euthanatized between 7 and 30 days after surgery. Incipient reepithelialization was evident histologically on day 14, and complete reepithelialization of the surgery site was evident by day 47. CONCLUSION AND CLINICAL RELEVANCE: Results suggest that ventriculocordectomy can safely be performed with an Nd:YAG laser in standing horses.     

Assessment of the efficacy of an abductor muscle prosthesis for treatment of laryngeal hemiplegia in horses

Four variations of abductor muscle prosthesis for treating laryngeal hemiplegia were evaluated in 153 horses by questionnaire, and in the 100 Thoroughbred racehorses in this group survival analysis was used to compare their racing performances and earnings with those of 400 control horses. The questionnaire indicated that the technique which included a ventriculectomy and 2 prostheses was regarded as being the most successful (P less than 0.01) and resulted in the least residual stertor (P less than 0.001). Survival analysis showed that there was no significant difference between the treated group of horses and the control horses (P greater than 0.05).     

A comparison of laryngoplasty and modified partial arytenoidectomy as treatments for laryngeal hemiplegia in exercising horses

OBJECTIVE: To compare upper airway mechanics, arterial blood gases, and tracheal contamination in horses with induced left laryngeal hemiplegia (recurrent laryngeal neuropathy [RLN]) treated by laryngoplasty/vocal cordectomy (LPVC) or modified partial arytenoidectomy (MPA). STUDY DESIGN: Repeated measures under the following conditions: Control, RLN, LPVC, and MPA. ANIMALS: Six horses. METHODS: Two trials were conducted under all conditions at 80% and 100% of maximal heart rate (HR(max)). In Trial 1, arterial blood gases, tracheal and pharyngeal pressures, and laryngeal videoendoscopy were recorded. In Trial 2, upper airway pressure and airflow were determined. Tracheobronchial aspirates were performed after exercise to quantify airway contamination. RESULTS: Compared with control, RLN significantly increased inspiratory impedance and worsened exercise-induced hypoxemia. At 80% HR(max), LPVC restored most variables to control values. At 100% HR(max), LPVC improved all variables, but did not restore minute volume, arterial pH, and PaCO(2). At 80% HR(max), MPA restored all variables except bicarbonate to control values. At 100% HR(max), MPA improved all variables, but did not statistically restore minute ventilation or bicarbonate level. Only minor differences were noted between LPVC and MPA. Both resulted in equivalent tracheal contamination. CONCLUSIONS: Airway mechanics and arterial blood gas values were not restored to normal after either LPVC or MPA in horses exercising at HR(max). This does not affect ventilation at sub-maximal exercise, but has clinical implications at HR(max). Both procedures diminish normal laryngeal protective mechanisms. CLINICAL RELEVANCE: At sub-maximal exercise intensities both LPVC and MPA restore airway ventilation to normal. At maximal exercise the superiority of LPVC over MPA is slight.     

Laryngoplasty with ventriculectomy or ventriculocordectomy in 104 draft horses (1992-2000)

OBJECTIVE: To evaluate efficacy and safety of laryngoplasty with vetriculectomy (VE) or ventriculocordectomy (VCE) for treatment of laryngeal hemiplegia (LH) in draft horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: One hundred four draft horses used for competitive hitch competitions. METHODS: Medical records and postoperative endoscopy for competitive hitch draft horses diagnosed with left LH and treated with laryngoplasty and VE or VCE between January 1992 and December 2000 were reviewed. Follow-up information was obtained from telephone interviews with owners and trainers, and performance scores of 1 to 3 were assigned in which 1 was defined as a horse that was unable to perform (abnormal respiratory noise with or without exercise intolerance), 2 was able to perform but not for its intended use (exercise tolerant but abnormal respiratory noise), and 3 was performing as expected for its intended use (exercise tolerant, no abnormal respiratory noise). RESULTS: One hundred four horses that had 111 laryngoplasty procedures were included. All horses had preoperative performance scores of 1. Follow-up information was available for 79 horses. Improvement in postoperative performance (exercise tolerant, with or without abnormal respiratory noise) was reported in 92% of horses. Respiratory noise was eliminated in 72% (57 horses) of horses. Postoperative performance scores were the following: 3 in 57 (72%) horses, 2 in 16 (20%) horses, and 1 in 6 (8%) horses. There was no significant difference in postoperative performance based on preoperative grade of LH. There was a trend for horses with >/=70% of possible maximal abduction postoperatively to have a performance score of 3. Postanesthetic complications included prolonged recovery (4 horses, 4%) and myopathy or neuropathy (7 horses, 7%). One of these horses was killed because it did stand; triceps myopathy and encephalopathy were confirmed on necropsy. CONCLUSIONS: Laryngoplasty with VE or VCE is an effective and safe procedure for the treatment of LH in the draft horse. Repeat laryngoplasty can be performed successfully, with good performance outcome after laryngoplasty failure. Complications associated with general anesthesia and laryngoplasty in draft horses are higher than reported for light breed horses under similar conditions. CLINICAL RELEVANCE: For LH, laryngoplasty with VCE or VE under general anesthesia is recommended to eliminate abnormal respiratory noise and improve performance in most competitive hitch draft horses.     

Spectrum analysis of respiratory sounds in exercising horses with experimentally induced laryngeal hemiplegia or dorsal displacement of the soft palate

OBJECTIVE: To record respiratory sounds in exercising horses and determine whether spectrum analysis could be use to identify sounds specific for laryngeal hemiplegia (LH) and dorsal displacement of the soft palate (DDSP). ANIMALS: 5 Standardbred horses. PROCEDURE: Respiratory sounds were recorded and pharyngeal pressure and stride frequency were measured while horses exercised at speeds corresponding to maximum heart rate, before and after induction of LH and DDSP. RESULTS: When airway function was normal, expiratory sounds predominated and lasted throughout exhalation. After induction of LH, expiratory sounds were unaffected; however, all horses produced inspiratory sounds characterized by 3 frequency bands centered at approximately 0.3, 1.6, and 3.8 kHz. After induction of DDSP, inspiratory sounds were unaffected, but a broad-frequency expiratory sound, characterized by rapid periodicity (rattling) was heard throughout expiration. This sound was not consistently detected in all horses. CONCLUSIONS AND CLINICAL RELEVANCE: The technique used to record respiratory sounds was well tolerated by the horses, easy, and inexpensive. Spectrum analysis of respiratory sounds from exercising horses after experimental induction of LH or DDSP revealed unique sound patterns. If other conditions causing airway obstruction are also associated with unique sound patterns, spectrum analysis of respiratory sounds may prove to be useful in the diagnosis of airway abnormalities in horses.     

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.