Laryngoplasty With or Without Ventriculectomy for Treatment of Left Laryngeal Hemiplegia in 230 Racehorses

Objective —The purpose of this study was to examine the influence of laryngoplasty on racing performance and to determine if any of the following variables had a significant effect on outcome: breed (Thoroughbred v Standardbred), endoscopic grade of laryngeal function, ventriculectomy versus no ventriculectomy, type of prosthetic suture used, and number of prostheses placed. Study Design —Retrospective study of laryngoplasty with or without ventriculectomy for treatment of left laryngeal hemiplegia in racehorses between 1986 and 1993. Animals or Sample Population —230 horses (174 Thoroughbreds, 56 Standardbreds). Methods —The medical records of racehorses or horses intended for racing were reviewed. Signalment, admitting complaints, physical examination findings, resting endoscopic grade of laryngeal function, type of prosthetic suture material used, number of prosthetic sutures placed, presence or absence of ventriculectomy, and postoperative complications were recorded. Results —Upper respiratory tract noise and exercise intolerance were the most common presenting complaints. Two horses had a laryngeal grade of 2, 109 horses a laryngeal grade of 3, and 119 horses a laryngeal grade of 4. Two double-strand braided polyester sutures were used in 147 horses, a single double-strand polyester suture was used in 49 horses, and a single double-strand nylon suture was used in 34 horses. Ventriculectomy was performed on 186 horses. The most common complication recognized during hospitalization was coughing in 50 horses. Telephone follow-up was obtained for 176 horses. For 168 horses, respiratory noise after surgery was decreased in 126 horses, the same in 28, and increased in 14. After hospital discharge, coughing occurred in 43 of 166 horses, and a nasal discharge occurred in 26 horses. Postoperative racing performance for 167 horses was subjectively evaluated by respondents as being improved in 69% of the horses. Overall owner satisfaction with the outcome after surgery was 81%. Of 230 horses, 178 raced at least one time after surgery. Overall, 117 horses raced three or more times before and after surgery, and 65 of these horses had improved performance index scores. None of the variables of surgical interest affected performance index scores. Conclusions and Clinical Relevance —Laryngoplasty with or without ventriculectomy allowed 77% of the horses to race at least one time after surgery, improved racing performance in 56% of the horses that completed three races before and after surgery, and improved subjectively evaluated racing performance in 69% of the horses.     

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.     

Long-term survey of laryngoplasty and ventriculocordectomy in an older,mixed-breed population of 200 horses. Part 2: Owners' assessment of the value of surgery

REASONS FOR PERFORMING STUDY: There is continuing debate on the clinical benefit of laryngoplasty (LP) in the treatment of equine laryngeal paralysis. In particular, there is little information available on the clinical value of this surgery in older horses, in non-Thoroughbreds or in sports or pleasure horses; nor on the relationship between the degree of LP abduction achieved and the clinical value of LP. OBJECTIVES: To evaluate the owner's assessment of the value of LP (and combined ventriculocordectomy) in an older, mixed breed and mixed workload population of horses and to also assess the relationship between the degree of LP abduction present and the clinical value of this surgery. METHODS: A study (1986-1998) of 200 horses of mixed breed and workload, median age 6 years (prospective 136 cases and retrospective 64 cases) undergoing LP and ventriculocordectomy was undertaken. The degree of laryngoplasty abduction achieved and maintained was semiquantitatively evaluated using a 5-grade system. RESULTS: A survey of 198 owners, a median of 19 months after LP surgery, showed that 91% of cases had returned to full work and 3% to reduced work, including 95% of horses with good (Grade 2) laryngoplasty abduction at 6 weeks after surgery, 91% with moderate (Grade 3) abduction, 88% of cases with minsimal (Grade 4) abduction and just 25% of cases with total loss of surgical abduction (Grade 5). Once back in work, 73% of cases were reported to make no abnormal exercise-related noises ('noises') at exercise, with reduced 'noises' reported in some of the 21% of horses that still made 'noises'. In the other 6% of cases, owners were unsure if 'noises' were present. The absence or presence of 'noises' once back at work correlated significantly with the degree of surgical arytenoid abduction present at 6 weeks after LP. Once back in work, 'noises' were less commonly detected in sports and pleasure horses (absent in 76% of cases) than in racehorses (absent in 60%) of cases. Exercise performance following surgery was reported to be markedly increased in 75% of cases, with 10% showing no difference in exercise performance, 3% showing worse performance, and owners unsure of any effect on exercise performance in 13% of cases. Improved work was reported in 70% of sports and pleasure horses and in 67% of racehorses. Overall, 86% of owners believed LP was worthwhile, 7% believed it was not worthwhile and 6% were unsure of its value. Surgery was reported to be of most benefit to sports horses (e.g. reported worthwhile for 100% of show jumpers) and of least benefit to National Hunt (long distance) racehorses where 71% of owners believed it to be worthwhile. CONCLUSIONS AND POTENTIAL RELEVANCE: Most horse-owners believe that LP and combined ventriculocordectomy are of clinical value, especially in sports and pleasure horses. Large scale physiological studies on clinical cases, pre- and post operatively, are required to examine more critically the value of such surgery.     

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.     

Upper airway dysfunction associated with collapse of the apex of the corniculate process of the left arytenoid cartilage during exercise in 15 horses

OBJECTIVE: To report dynamic collapse of the apex of the left corniculate process under the right corniculate process into the airway at the dorsal apposition of the paired arytenoid cartilages during exercise as a cause of upper airway dysfunction in horses. DESIGN: Retrospective study. ANIMALS: Fifteen horses with a history of poor performance and/or upper respiratory tract noise during exercise. METHODS: Video recordings of all horses referred for upper airway evaluation using high-speed treadmill videoendoscopy (HSTV) between January 1998 and December 2003 were reviewed. Records of horses that developed dynamic collapse of the apex of the left corniculate process into the airway were included. Clinical history, age, gender, breed, and use of the horse were retrieved. RESULTS: Of 309 horses referred for examination for poor performance and/or upper respiratory tract noise during exercise, 15 (4.9%) had collapse of the apex of the left corniculate process under the right and into the airway at the dorsal apposition between the paired arytenoid cartilages during HSTV. There were 3 females and 13 males, aged from 2 to 5 years. Five horses had previous surgery for left recurrent laryngeal neuropathy (RLN): 2 had nerve muscle pedicle graft and 3 had laryngeal prosthesis. During HSTV, all 15 horses had progressive collapse of the apex of the left corniculate process under the right at the dorsal apposition of the 2 arytenoid cartilages, and into the dorsal aspect of the rima glottidis. Review of video recordings revealed that collapse of the apex of the corniculate process was followed by progressive collapse of the left aryepiglottic fold and left vocal fold. The ventral aspect of the left corniculate cartilage maintained abduction in all horses. Two horses also had progressive collapse of the right vocal fold, 1 had rostral displacement of the palatopharyngeal arch, and another had dorsal displacement of the soft palate. CONCLUSIONS: Dynamic collapse of the apex of the left corniculate process of the arytenoid cartilage under the right is an uncommon cause of upper airway dysfunction in horses and the pathogenesis is unclear. We speculate that the left arytenoideus transversus muscle is unable to support the dorsal apposition between the arytenoid cartilages. This loss of support allows the elastic cartilage of the left corniculate process to collapse under the right and into the airway, as inspiratory pressure increases during exercise. This condition may be associated with an unusually advanced neuropathy of the adductor components of the left recurrent laryngeal nerve and may be an unusual manifestation of RLN; however, this is speculative and further investigation is required to determine its cause. CLINICAL RELEVANCE: Dynamic collapse of the apex of the left corniculate process and into the airway at the dorsal apposition between the paired arytenoid cartilages can only be diagnosed during HSTV. It is an uncommon cause of upper airway dysfunction but may affect the athletic potential of racing Thoroughbreds and Standardbreds.     

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.     

Indications for and short- and long-term outcome of permanent tracheostomy performed in standing horses: 82 cases (1995-2005)

OBJECTIVE: To identify indications for and short- and long-term outcome of permanent tracheostomy performed in standing horses. DESIGN: Retrospective case series. ANIMALS: 82 horses undergoing permanent tracheostomy. PROCEDURES: Data obtained from medical records included signalment, diagnosis, surgical technique, complications, use of the horse before and after surgery, and owner satisfaction. Follow-up information was obtained through a telephone questionnaire administered to owners. RESULTS: Indications for permanent tracheostomy included nasopharyngeal cicatrix (n = 59), arytenoid chondropathy (55), and laryngeal hemiplegia (20); 54 horses had multiple indications for tracheostomy. Complications identified prior to discharge included partial dehiscence (n = 8), transient fever (10), and excessive swelling (13). Complications identified after discharge included partial dehiscence (n = 3), inversion of skin (2), and stenosis of the tracheostomy requiring repair (1). Long-term follow-up information was available for 64 horses. Fifty-seven of the 64 (89%) horses returned to their previous use, and owners of 63 (98%) horses reported being very satisfied with the results. The owner of 1 (2%) horse was unsatisfied with the results. The 1-year survival rate was 97% (95% confidence interval, 95% to 100%). Mean estimated truncated survival time (ie, failure-free period) was 9.7 years (95% confidence interval, 9.3 to 10.1 years). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that permanent tracheostomy can be safely performed in standing horses and was a viable treatment for horses with obstructive disease of the upper respiratory tract that was unresponsive to medical treatment or other surgical treatments.     

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.     

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.     

Effects of unilateral laser-assisted ventriculocordectomy in horses with laryngeal hemiplegia

REASONS FOR PERFORMING STUDY: Recent studies have evaluated surgical techniques aimed at reducing noise and improving airway function in horses with recurrent laryngeal neuropathy (RLN). These techniques require general anaesthesia and are invasive. A minimally invasive transnasal surgical technique for treatment of RLN that may be employed in the standing, sedated horse would be advantageous. OBJECTIVE: To determine whether unilateral laser-assisted ventriculocordectomy (LVC) improves upper airway function and reduces noise during inhalation in exercising horses with laryngeal hemiplegia (LH). METHODS: Six Standardbred horses were used; respiratory sound and inspiratory transupper airway pressure (Pui) measured before and after induction of LH, and 60, 90 and 120 days after LVC. Inspiratory sound level (SL) and the sound intensities of formants 1, 2 and 3 (Fl, F2 and F3, respectively), were measured using computer-based sound analysis programmes. In addition, upper airway endoscopy was performed at each time interval, at rest and during treadmill exercise. RESULTS: In LH-affected horses, Pui, SL and the sound intensity of F2 and F3 were increased significantly from baseline values. At 60 days after LVC, Pui and SL had returned to baseline, and F2 and F3 values had improved partially compared to LH values. At 90 and 120 days, however, SL increased again to LH levels. CONCLUSIONS: LVC decreases LH-associated airway obstruction by 60 days after surgery, and reduces inspiratory noise but not as effectively as bilateral ventriculocordectomy. POTENTIAL RELEVANCE: LVC may be recommended as a treatment of LH, where reduction of upper airway obstruction and respiratory noise is desired and the owner wishes to avoid risks associated with a laryngotomy incision or general anaesthesia.     

Endoscopy of the upper respiratory tract during treadmill exercise: a clinical study of 100 horses

SUMMARY: Endoscopy of the upper respiratory tract was performed in 100 horses during high speed treadmill exercise. Reasons for endoscopy were a history of an abnormal noise during exercise in 75 horses, poor performance in 17 horses and to evaluate the results of upper respiratory tract surgery in 8 horses. Of the 75 horses with a history of an abnormal noise during exercise the cause was determined in 67 (89%). Endoscopic abnormalities were detected at rest in 40 of these 75 horses (53%). In these 40 horses, a similar diagnosis as to the cause of the abnormal noise was made at rest and during exercise on the treadmill in 19 cases, while in the remaining 21 the endoscopic findings during exercise varied from that seen at rest. This included 3 horses in which a diagnosis was made at rest but no abnormalities were detected during exercise. Some of the findings during treadmill endoscopy included laryngeal dysfunction, grades 3, 4 and 5 (22 cases), dorsal displacement of the soft palate (20), epiglottic entrapment (8), epiglottic flutter (4), aryepiglottic fold flutter (4), pharyngeal collapse (3), arytenoiditis (3), vocal cord flutter (3), false nostril noise (2), pharyngeal lymphoid hyperplasia (2), soft palate haemorrhage (1) and positional arytenoid collapse (1). More than one abnormality was observed during exercise in 7 horses. A complete and correct diagnosis based on the resting endoscopy findings alone was made in 19 (25%) of these 75 cases. In the 17 horses examined because of poor performance, no abnormalities were detected during treadmill endoscopy that were not evident at rest. None of these 17 horses presented with a history of an abnormal respiratory noise, although one, diagnosed as having grade 4 laryngeal function at rest and exercise, did make a characteristic inspiratory noise during treadmill exercise. Eight horses were evaluated after surgery for correction of laryngeal hemiplegia, as the post-operative performance or the amount of respiratory noise present was considered unsatisfactory. Of these, 3 were found to have a satisfactory airway during exercise and other reasons for poor performance were detected; 3 had insufficient abduction; and 2 had intermittent dorsal displacement of the soft palate. Endoscopy of the upper respiratory tract was found to be a useful technique for evaluating the cause of abnormal respiratory noise in most cases. We concluded that treadmill endoscopy in horses presented for poor performance, without a history of an abnormal respiratory noise, was of little value. The technique, in conjunction with arterial blood gas measurements, was useful in determining the efficacy of surgical treatment of laryngeal hemiplegia.     

Laryngeal paralysis: a study of 375 cases in a mixed-breed population of horses

Referred cases (n = 375) of laryngeal paralysis (1985-1998) from a mixed-breed equine population included 351 (94%) cases of recurrent laryngeal neuropathy (RLN) (idiopathic laryngeal hemiplegia) and 24 cases (6%) of laryngeal paralysis from causes other than RLN. Laryngeal movements were classified endoscopically into one of 6 grades, in contrast to the usual 4 grades. The RLN cases had a median grade 4 laryngeal paralysis, of which 96% were left-sided, 2% right-sided and 2% bilaterally affected. RLN cases included 204 (58%) Thoroughbred, 96 (27%) Thoroughbred-cross, 23 (7%) draught, 16 (5%) Warmbloods and 10 (3%) other breeds, including only 4 (1%) ponies. The median age of RLN cases at referral was 6 years (range 2-12) and their median height was 170.2 cm. The work of RLN horses included National Hunt racing (42%), flat racing (1%), hunting (19%), eventing (16%) and miscellaneous work (22%). Reported presenting signs in RLN-affected horses included abnormal exercise-related respiratory sounds in 90% and reduced exercise tolerance in only 64%. However, many horses were referred before their exercise tolerance could be fully assessed. Forty percent of the RLN cases had intercurrent disorders, including 10% with additional upper respiratory and 7% with lower respiratory tract diseases. The 24 nonidiopathic RLN cases included 12 with bilateral laryngeal paralysis, 11 (92%) of which were ponies. Bilateral laryngeal paralysis occurred with hepatic encephalopathy in 7 cases and following general anaesthesia in 2 cases. The 12 cases of acquired unilateral laryngeal paralysis included 7 caused by guttural pouch mycosis.     

Racing Performance in 72 Racehorses Treated with Prosthetic Laryngoplasty for Laryngeal Hemiplegia

The purpose of this study was to compare racing performance before and after prosthetic laryngoplasty for treatment of laryngeal hemiplegia in inexperienced (horses without at least one start before surgery) and experienced (horses with at least one start before surgery) Thoroughbred and Quarter Horse racehorses. Medical records of 54 Thoroughbred and 18 Quarter Horse racehorses or horses intended for racing treated with prosthetic laryngoplasty and unilateral ventriculectomy for laryngeal hemiplegia were reviewed. Signalment, age at the time of surgery, resting endoscopic grade of laryngeal function, surgical procedure, and type of suture were recorded. Median performance index (PI), earnings, distance, and Beyer speed figure (BSF) per start for three races before and after surgery were compared, and factors associated with improved postsurgical performance were evaluated. Seventy-three percent of horses that had not raced before surgery and 84% of horses that competed in at least one race before surgery were able to return to racing after surgery. Fifty-nine percent and 27% of Thoroughbreds and Quarter Horses, respectively, were able to improve their PI after surgery. Sixty-two percent and 20% of Thoroughbreds and Quarter Horses, respectively, significantly increased their distance after surgery. Additionally, 61% and 66% of racehorses were able to increase their earnings and BSF after surgery, respectively. Horses treated with laryngoplasty and unilateral ventriculectomy have a good prognosis for return to racing. Inexperienced racehorses have a better prognosis for improvement after surgery than do experienced racehorses. Thoroughbred racehorses have a better success rate than Quarter Horse racehorses.     

Causes of poor performance of horses during training, racing, or showing: 348 cases (1992-1996)

OBJECTIVE: To determine results for horses undergoing a high-speed treadmill examination, including videoendoscopy of the pharynx and larynx before and during exercise, echocardiography before and after exercise, and electrocardiography before, during, and after exercise, because of poor performance. DESIGN: Retrospective study. ANIMALS: 348 horses. RESULTS: A definitive diagnosis was obtained for 256 (73.5%) horses. One hundred forty-eight horses had dynamic obstruction of the airway during exercise, 33 had clinically important cardiac arrhythmias alone, 22 had a combination of dynamic airway obstruction and clinically important cardiac arrhythmias, 19 had poor cardiac fractional shortening immediately after exercise, 10 had exertional rhabdomyolyis, 15 had clinically apparent lameness, and 9 had other disorders. Thirty-nine of the horses with dynamic obstruction of the airway during exercise had multiple airway abnormalities. Fifty-three horses also had subclinical myopathy CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a complete evaluation, including a high-speed treadmill examination, should be conducted in horses with poor performance, regardless or whether horses do or do not have a history of abnormal respiratory noises and particularly if the horses have grade-II or -III left laryngeal hemiplegia.     

Clinical and endoscopic evidence of progression in 152 cases of equine recurrent laryngeal neuropathy (RLN)

Examination of the long-term histories and clinical findings was performed in 351 horses suffering from recurrent laryngeal neuropathy (RLN) to examine for possible evidence of progression of this disorder. Fifty-two out of 351 cases (15%) had evidence of progression of the degree of laryngeal dysfunction over a median period of 12 months (range 1.5-48 months) with the onset of progression occurring at median age 7 years. In 30 cases, there was both endoscopic (median deterioration of 3 endoscopic grades; range 1-5 grades) and clinical evidence, with 29 (97%) of these horses concurrently developing sudden-onset, abnormal exercise-related respiratory 'noises' and 13 (43%) concurrently reporting reduced exercise performance. In the remaining 22 horses there was solely clinical evidence of RLN progression, including the sudden onset of abnormal exercise-related respiratory sounds in 16 (73%) and the worsening of such sounds in 6 (23%), associated with reduced exercise performance in 13 (59%) of these 22 cases. Endoscopically, 13 (59%) of the latter 22 cases had marked (total or almost total) RLN that did not appear compatible with their previous exercise-performance histories. This evidence of progression of RLN may be of particular significance in disputes concerning horses that are apparently normal at pre-purchase examination but are later shown to have RLN and also in the surgical treatment of less severe cases of RLN.     

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.     

Excision of Intralaryngeal Granulation Tissue in 25 Horses Using a Neodymium:YAG Laser (1986 to 1991)

Granulation tissue masses arising from the axial surface of the arytenoid cartilage in 25 horses were excised using a contact neodymium:yttrium aluminum garnet laser. A technique that eliminated the need for general anesthesia or laryngotomy was developed for transen-doscopic removal of the masses in standing horses. Nineteen racehorses made abnormal upper respiratory tract noises or their performance was decreased, whereas six horses not used for racing had a history of stertor (five horses) or epistaxis after nasogastric intubation (one horse). Thoroughbreds were significantly (p = .0126) overrepresented compared with the hospital population. The granulation tissue masses were successfully excised and the defect healed in all 25 horses, although a second excision of granulation tissue regrowth was necessary in four horses. In 21 horses, the underlying chondrosis did not progress appreciably. In four horses with preexisting moderate arytenoid cartilage thickening and concurrent laryn-geal abnormalities, the surgery site healed but the underlying chondrosis progressed substantially. Twelve of 19 (63%) racehorses returned to race at least three times after the surgery. Of the 19 racehorses, five had only slight arytenoid cartilage involvement whereas 14 had moderate cartilage thickening or concurrent laryngeal pathology. All five horses with slight apparent arytenoid cartilage involvement and no concurrent laryngeal pathology returned to racing. Seven of the 14 horses (50%) with moderate underlying cartilage thickening or concurrent laryngeal pathology returned to racing. The six horses not used for racing returned to their previous activity without further respiratory problems.     

Association of owner-reported noise with findings during dynamic respiratory endoscopy in Thoroughbred racehorses

Reasons for performing study: To determine the association between owner‐reported noise and findings during dynamic respiratory endoscopy (DRE) in a large case series. Hypothesis: The sensitivity of owner‐reported noise for dynamic upper respiratory tract obstructions in horses is low, and the specificity is high. Methods: One hundred horses underwent DRE for the investigation of abnormal respiratory noise and/or poor performance. The association of abnormal noise with findings during DRE was evaluated. Results: Eighty‐five horses underwent DRE for the investigation of abnormal respiratory noise. Of these, 82% were found to have one or more obstructive upper respiratory tract abnormalities during DRE. Forty‐eight percent of horses reported to gurgle, rattle or make a rough noise were diagnosed with solitary palatal dysfunction. A further 24% with this history showed palatal dysfunction in combination with an additional abnormality. Twenty‐seven percent of horses with a history of whistling or roaring showed some degree of recurrent laryngeal neuropathy. Seven percent of horses with a history of whistling or roaring had vocal cord collapse as a solitary condition, whereas 40% had vocal cord collapse and another abnormality. The sensitivity of abnormal respiratory noise for any obstruction of the upper portion of the respiratory tract was high (84%), while the specificity was low (25%). Characteristic owner reported noise patterns showed moderate to low sensitivity for specific conditions. Whistling and roaring showed the highest specificity (≥80%) for laryngeal dysfunction. Conclusion: Diagnosis of upper respiratory tract obstructions based solely on owner‐reported noise and performance history may result in incomplete diagnoses. Clinical relevance: DRE should be performed in horses with abnormal respiratory noise to rule out complex conditions of the upper portion of the respiratory tract.     

Laryngeal Hemiplegia in Draft Horses A Review of 27 Cases

Case records of 27 draft horses with laryngeal hemiplegia were reviewed. Twenty-one horses were treated by ventriculectomy with or without prosthetic laryngoplasty, and 17 owners were contacted to determine the results. Fifteen horses improved after surgery and were able to perform to the owners' expectations. Performance improved significantly and hospitalization was shorter after ventriculectomy alone. Results of this study indicate that the clinical signs of exercise intolerance and excessive inspiratory noise associated with left laryngeal hemiplegia in draft horses can be treated successfully by ventriculectomy without prosthetic laryngoplasty.     

Clinical experiences with axial deviation of the aryepiglottic folds in 52 racehorses

OBJECTIVE: To describe the clinical findings in 52 racehorses with axial deviation of the aryepiglottic folds (ADAF) and to report outcome in 33 of these horses after either rest or transendoscopic laser excision of aryepiglottic fold tissue. STUDY DESIGN: Retrospective study. Animal or SAMPLE POPULATION: Racehorses admitted for high-speed treadmill (HST) evaluation of poor performance. METHODS: Medical records and videotapes of resting and exercising videoendoscopic examinations were reviewed. Racing performance records and owner or trainer interviews, at least 1 year after HST examination, were used to compare results after either surgical management or rest in 33 horses with ADAF and no other upper-airway abnormalities. RESULTS: ADAF occurred in 6% of horses evaluated for poor performance. No breed or gender predisposition existed, but horses with ADAF were younger than the overall population evaluated on the HST. Of 52 horses with ADAF, 19 horses had at least one other upper-airway abnormality. There was no apparent association between ADAF and other causes of dynamic upper-respiratory obstruction. Surgical correction was successfully performed in standing or anesthetized horses without complications. When ADAF was the only upper-airway obstruction, 75% of horses that had surgery and 50% of rested horses had objective improvement in performance. Owners and trainers also perceived greater improvement in performance in horses that had surgery. CONCLUSIONS: Whereas surgical management of ADAF is recommended, clinical experience indicated that it is not required to resolve ADAF in all horses. However, owners and trainers of horses that had surgery were more satisfied with outcome than those with horses managed conservatively. CLINICAL RELEVANCE: Diagnosis of ADAF can only be made by videoendoscopic evaluation during high-speed exercise. Transendoscopic laser excision of the collapsing portion of the aryepiglottic folds can be performed safely in standing horses and results in resolution of airway obstruction and rapid return to training.