Eric J. Parente

Disorders of the larynx

The upper respiratory tract is a frequent cause of exercise intolerance in horses, particularly in racing horses. There are a myriad of laryngeal abnormalities that may restrict airflow at the rima glottidis. Careful endoscopic examination is a crucial part of the examination of any racing horse suffering from poor performance. There has recently been interest in spectrum analysis of respiratory sounds. It has been determined that laryngeal hemiplegia and dorsal displacement of the soft palate have unique sound patterns. Therefore, spectrum analysis of respiratory sounds may prove to be useful in the diagnosis of laryngeal disorders in horses. Accurate diagnosis and appropriate surgical intervention are necessary to provide the horse the best chance of returning to its full athletic potential.

Exercising upper respiratory videoendoscopic evaluation of 100 nonracing performance horses with abnormal respiratory noise and/or poor performance.

REASONS FOR PERFORMING STUDY Although well documented in racehorses, there is paucity in the literature regarding the prevalence of dynamic upper airway abnormalities in nonracing performance horses. OBJECTIVE To describe upper airway function of nonracing performance horses with abnormal respiratory noise and/or poor performance via exercising upper airway videoendoscopy. METHODS Medical records of nonracing performance horses admitted for exercising evaluation with a chief complaint of abnormal respiratory noise and/or poor performance were reviewed. All horses had video recordings of resting and exercising upper airway endoscopy. Relationships between horse demographics, resting endoscopic findings, treadmill intensity and implementation of head and neck flexion during exercise with exercising endoscopic findings were examined. RESULTS Dynamic upper airway obstructions were observed in 72% of examinations. Head and neck flexion was necessary to obtain a diagnosis in 21 horses. Pharyngeal wall collapse was the most prevalent upper airway abnormality, observed in 31% of the examinations. Complex abnormalities were noted in 27% of the examinations. Resting laryngeal dysfunction was significantly associated with dynamic arytenoid collapse and the odds of detecting intermittent dorsal displacement of the soft palate (DDSP) during exercise in horses with resting DDSP was only 7.7%. Exercising endoscopic observations were different from the resting observations in 54% of examinations. CONCLUSIONS Dynamic upper airway obstructions were common in nonracing performance horses with respiratory noise and/or poor performance. Resting endoscopy was only helpful in determining exercising abnormalities with recurrent laryngeal neuropathy. POTENTIAL RELEVANCE This study emphasises the importance of exercising endoscopic evaluation in nonracing performance horses with abnormal respiratory noise and/or poor performance for accurate assessment of dynamic upper airway function.

Exercising Videoendoscopic Evaluation of 45 Horses with Respiratory Noise and/or Poor Performance After Laryngoplasty

OBJECTIVE To (1) assess upper airway function by videoendoscopy in horses performing poorly after laryngoplasty and (2) establish whether dynamic collapse of the left arytenoid can be predicted by the degree of resting postsurgical abduction. STUDY DESIGN Case series. ANIMALS Horses that had left laryngoplasty (n=45). METHODS Medical records (June 1993-December 2007) of horses evaluated for abnormal respiratory noise and/or poor performance after laryngoplasty were reviewed. Horses with video recordings of resting and exercising upper airway endoscopy were included and postsurgical abduction categorized. Horses with immediate postoperative endoscopy recordings were also evaluated and postsurgical abduction categorized. Relationships between resting postsurgical abduction and historical information with exercising endoscopic findings were examined. RESULTS Dynamic collapse of the left arytenoid cartilage was probable in horses with no postsurgical abduction and could not be predicted in horses with grade 3 or 4 postsurgical abduction. Respiratory noise was associated with upper airway obstruction but was not specific for arytenoid collapse. Most horses with a left vocal fold had billowing of the fold during exercise. Other forms of dynamic collapse involved the right vocal fold, aryepiglottic folds, corniculate process of left arytenoid cartilage, dorsal displacement of soft palate, and pharyngeal collapse. Complex obstructions were observed in most examinations and in all horses with exercising collapse of the left arytenoid cartilage. CONCLUSIONS There was no relationship between exercising collapse of the left arytenoid cartilage and grade 3 or 4 postsurgical abduction but was likely in horses with no abduction.

Surgical complications of the equine upper respiratory tract.

Upper respiratory abnormalities are common performance-limiting problems in horses. The complications of various treatment methods, including laryngoplasty surgery, sinus surgery, intermittent dorsal displacement of the soft palate, laser surgery, and tracheal disorders, are discussed.

A Modified Laryngoplasty Approach Promoting Ankylosis of the Cricoarytenoid Joint

Objective: To perform a modification to the standard laryngoplasty procedure in vivo that would result in ankylosis of the cricoarytenoid (CA) joint, and determine the stability provided to the abducted arytenoid in vitro. Study Design: Experimental study. Animals: Horses (n=8). Methods: Horses were assigned to either control laryngoplasty (n=3) or modified laryngoplasty (5) procedure. Endoscopic upper airway evaluations were used to measure right:left quotients 1 day and 3 months postoperatively to assess maintenance of abduction. Horses were euthanatized 3 months after surgery and larynges collected for measurement of translaryngeal impedance and histologic evaluation of CA joint ankylosis. Each specimen was exposed to increasing negative pressure with the sutures intact or cut while translaryngeal impedance was recorded. Data were analyzed using ANOVA with significance set at P<.05. Results: Loss of left arytenoid cartilage abduction at 3 months was greater in the control laryngoplasty group. Overall, impedance was significantly lower for the modified laryngoplasty group compared with the control laryngoplasty group and lower with the sutures intact than cut. Histologic evaluation of the joints confirmed fibrous bridging of the left CA joints of the modified laryngoplasty group. Conclusions: A modified laryngoplasty approach promotes ankylosis of the CA joint and decreases the loss of abduction of the arytenoid.OBJECTIVE To perform a modification to the standard laryngoplasty procedure in vivo that would result in ankylosis of the cricoarytenoid (CA) joint, and determine the stability provided to the abducted arytenoid in vitro. STUDY DESIGN Experimental study. ANIMALS Horses (n=8). METHODS Horses were assigned to either control laryngoplasty (n=3) or modified laryngoplasty (5) procedure. Endoscopic upper airway evaluations were used to measure right:left quotients 1 day and 3 months postoperatively to assess maintenance of abduction. Horses were euthanatized 3 months after surgery and larynges collected for measurement of translaryngeal impedance and histologic evaluation of CA joint ankylosis. Each specimen was exposed to increasing negative pressure with the sutures intact or cut while translaryngeal impedance was recorded. Data were analyzed using ANOVA with significance set at P<.05. RESULTS Loss of left arytenoid cartilage abduction at 3 months was greater in the control laryngoplasty group. Overall, impedance was significantly lower for the modified laryngoplasty group compared with the control laryngoplasty group and lower with the sutures intact than cut. Histologic evaluation of the joints confirmed fibrous bridging of the left CA joints of the modified laryngoplasty group. CONCLUSIONS A modified laryngoplasty approach promotes ankylosis of the CA joint and decreases the loss of abduction of the arytenoid.

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.

Disorders of the pharynx

Pharyngeal disorders are complex and difficult to treat. Disorders that lead to anatomic derangement, such as trauma and neoplasia, can significantly affect the function of this organ. Pharyngeal dysfunction can manifest as dysphagia, persistent palatal displacement, or exercise intolerance. Secondary complications are serious and life threatening and include aspiration pneumonia, weight loss, and death. Pharyngeal disorders that are only recognizable during strenuous exercise are difficult to diagnose and are treated with limited success, even though they are responsible for significant economic losses with performance animals.

Mechanical evaluation of the equine laryngoplasty.

OBJECTIVES Mechanical evaluation of the equine laryngoplasty. STUDY DESIGN Experimental. ANIMAL POPULATION Cadaveric cricoid (n=36) and arytenoid (46) cartilages. METHODS Arytenoid and cricoid cartilage specimens were embedded for testing. Suture material (2 Ethilon, 5 Ethibond, or 5 Fiberwire) was inserted simulating laryngoplasty procedures. Constructs were evaluated in single or cyclic loading. Single cycle tests recorded load at failure and stiffness. Cyclical tests recorded displacement after 10,000 cycles. ANOVA and t-tests were used (significance P<.05). RESULTS The arytenoid Ethibond (241.10+/-47.67 N) constructs were stronger in single cycle than Ethilon (133.85+/-27.89 N) and Fiberwire (142.67+/-32.40 N). The cricoid Ethibond (220.39+/-49.11 N) constructs were stronger than Ethilon (171.93+/-21.19). The stiffness of Ethilon constructs was lower in both the arytenoid and cricoid compared with Ethibond and Fiberwire. The arytenoids failed at a lower load than the cricoids for Ethilon and Fiberwire but not Ethibond constructs. In cyclic testing complete failure of either cartilage did not occur. Arytenoid Ethibond constructs (0.43+/-0.21 mm) had less distraction than Ethilon (0.92+/-0.41 mm) and a trend for less compared with Fiberwire (0.83+/-0.43 mm; P=.0513). Cricoid Ethibond constructs (0.45+/-0.18 mm) had less distraction compared with Ethilon (1.04+/-0.30 mm) and Fiberwire (0.97+/-0.45 mm). CONCLUSIONS Ethibond was superior to Ethilon and Fiberwire constructs in vitro. CLINICAL RELEVANCE Abduction loss after laryngoplasty is a common complication. The results of this study suggest that the use of Ethibond should minimize abduction loss after surgery relative to the other materials tested.

Using Quarterly Earnings to Assess Racing Performance in 70 Thoroughbreds after Modified Laryngoplasty for Treatment of Recurrent Laryngeal Neuropathy

OBJECTIVE To validate and then use quarterly earnings to assess racing performance of Thoroughbreds after modified laryngoplasty for treatment of recurrent laryngeal neuropathy STUDY DESIGN Retrospective cohort study. ANIMALS Thoroughbred racehorses after modified laryngoplasty (N = 70), and untreated cohorts (N = 210). METHODS Medical (2005-2008) and race records of 70 Thoroughbred racehorses treated by modified laryngoplasty were reviewed. Postsurgery data were collated as the number of starts and the dollar race winnings for each quarter after the date of surgery. Comparisons were made to an untreated cohort population. Initial comparisons were made between subgroups of the untreated cohort to ensure that one randomly selected group of untreated horses would not differ significantly from another untreated group. RESULTS In the last race before surgery, treated horses performed significantly (P < .001) worse than untreated horses. When data were examined by quarter, with the exception of the first quarter after surgery, there were no significant differences in race starts or dollars earned between treated horses and untreated cohorts. All treated horses had at least 1 race after surgery and there was no difference in cumulative survival up to 40 races after surgery between treated and untreated groups CONCLUSIONS Quarterly earnings can be used to provide a more detailed longitudinal assessment of a racehorses performance. Horses treated by modified laryngoplasty for recurrent laryngeal neuropathy return to similar level of performance as their untreated cohorts by the second quarter after surgery, and continue to compete as long as their cohorts.

Epiglottic abnormalities in mature nonracehorses: 23 cases (1990-2009)

OBJECTIVE To identify history, clinical signs, endoscopic findings, treatment, and outcome of mature (> 8 years old) nonracehorses with epiglottic abnormalities. DESIGN Retrospective case series. ANIMALS 23 horses with an epiglottic abnormality. PROCEDURES Medical records of horses examined between 1990 and 2009 because of an epiglottic abnormality were reviewed to obtain information on signalment, history, clinical signs, clinical examination findings, upper airway endoscopic findings, diagnosis, surgical procedure, clinical management, postoperative care, and outcome. RESULTS Mean ± SD age was 16 ± 6 years (range, 9 to 30 years). Sixteen of the 23 (70%) horses had a primary complaint of a chronic cough. Thirteen (57%) horses had epiglottic entrapment, 7 (30%) had a subepiglottic granuloma, and 3 (13%) had a subepiglottic cyst. All 23 horses were treated surgically, with 1 (4%) requiring further surgical treatment. Follow-up examinations and conversations with owners indicated resolution of the primary complaint in 17 of the 23 (74%) horses, with 4 (24%) requiring prolonged medical treatment because of postoperative subepiglottic inflammation. Of the 6 horses without complete resolution, 4 (67%) had signs of recurrent airway obstruction and 2 (33%) developed persistent dorsal displacement of the soft palate following laryngotomy and subepiglottic membrane resection. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that coughing is a common complaint in mature nonracehorses with epiglottic abnormalities. Therefore, upper airway endoscopy is recommended in the evaluation of older horses with a cough. Surgical treatment can be beneficial in most horses, with some requiring further postoperative medical treatment.