The version presented here may differ from the published version or from the version of the recor... more The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.
Objective: To evaluate the efficacy of various treatments for dysphagia after laryngeal surgery. ... more 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.
the dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's resp... more the dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (psA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified "subclinical" subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically. Horses are highly developed athletes, able to reach a maximum speed approaching 88 Km/h with a maximal oxygen consumption of 200 ml/kg/min 1. Despite marked cardiovascular and musculoskeletal adaptations, the respiratory system represents a common limiting factor for oxygen delivery and athletic performance 1-3. Dilation of the rima glottis during exercise is a key, often rate limiting component of the upper airway patency and is maintained by contraction of the sole arytenoid abductor, the dorsal cricoarytenoid (DCA) muscle 1,4. The most common cause of dysfunction of the equine DCA muscle, and reduced athletic performance, is Recurrent Laryngeal Neuropathy (RLN). This disease is characterized by loss of large, alpha myelinated nerve fibers in (predominantly) the left distal recurrent laryngeal nerve (RLn) 5-9. The majority of the histological changes detected (Büngner bands, regenerating clusters, paranodal evaginations, and spheroids) are associated with primary axonal dysfunction and pathological features usually associated with primary myelinopathies (onion bulbs and demyelination), but that also occur in primary axonopathies (for the most recent review, see Draper and Piercy, 2018) 10. The aim of this study was to conduct a comprehensive electrodiagnostic study of the DCA muscles and recurrent laryngeal nerves to gather normative data in horses with normal laryngeal function at rest and during exercise. We performed needle electromyographic evaluation of the left and right DCA muscles during spontaneous breathing and following electrical stimulation of the RLn, with measurement of nerve conduction velocities bilaterally.
Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of ... more Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of airway obstruction and poor performance in racehorses. The definite etiology is still unclear, but through an experimental model, a role in the development of this condition was identified in the dysfunction of the thyro-hyoid muscles. The present study aimed to elucidate the nature of this dysfunction by investigating the spontaneous response to exercise of the thyro-hyoid muscles in racehorses with naturally occurring DDSP. Intramuscular electrodes were implanted in the thyro-hyoid muscles of nine racehorses, and connected to a telemetric unit for electromyographic monitoring implanted subcutaneously. The horses were recruited based on upper airway function evaluated through wireless endoscopy during exercise. Five horses, with normal function, were used as control; four horses were diagnosed as DDSP-affected horses based on repeated episodes of intermittent dorsal displacement of the soft palate. The electromyographic activity of the thyro-hyoid muscles recorded during incremental exercise tests on a high-speed treadmill was analyzed to measure the mean electrical activity and the median frequency of the power spectrum, thereafter subjected to wavelet decomposition. The affected horses had palatal instability with displacement on repeated exams prior to surgical implantation. Although palatal instability persisted after surgery, only two of these horses displaced the palate after instrumentation. The electromyographic traces from this group of four horses showed, at highest exercise intensity, a decrease in mean electrical activity and median power frequency, with progressive decrease in the contribution of the high frequency wavelets, consistent with development of thyro-hyoid muscle fatigue. The results of this study identified fatigue as the main factor leading to exercise induced palatal instability and DDSP in a group of racehorses. Further studies are required to evaluate the fiber type composition and metabolic characteristics of the thyro-hyoid muscles that could predispose to fatigue.
Reasons for performing study: Pharyngeal dysphagia is a debilitating, sometimes fatal condition i... more Reasons for performing study: Pharyngeal dysphagia is a debilitating, sometimes fatal condition in horses, with multiple aetiologies. The pathophysiology is complex and not fully understood. Treatment is largely supportive. Laryngeal advancement surgery may diminish symptoms of dysphagia and improve swallowing in affected horses. Objectives: 1) to induce reversible moderate and marked pharyngeal dysphagia by regional anaesthesia of branches of the glossopharyngeal (IX), vagus (X) and hypoglossal (XII) nerves; 2) to characterise the dysphagia produced by each model; and 3) to determine whether laryngeal advancement surgery improves swallowing in these models. Study design: Experimental design using 6 adult horses. Methods: Two dysphagia models were produced by blocking IX, the pharyngeal branch of X and XII unilaterally (moderate model) and only the pharyngeal branch of X bilaterally (marked model) within the guttural pouches. Both models were performed on each horse before and after surgery in order to assess the effectiveness of the surgical procedure as a potential treatment for pharyngeal dysphagia. Dysphagia was scored by partly blinded observers on a scale of 0-12 based on observations of eating (nonblinded), endoscopic examinations and fluoroscopic swallowing (blinded), where 0 = normal swallow and 12 = severe dysphagia with tracheal aspiration. Data were analysed by 3-factor ANOVA, with significance taken as P<0.05. Results: Dysphagia models were reversible, and horses swallowed normally within 3 h of model induction. The marked dysphagia model impaired movement of feed from the base of the tongue to the oesophagus and caused severe airway contamination. The average dysphagia score (mean ± s.d.) for the marked dysphagia model was 10.6 ± 1.1 before surgery and 6.1 ± 4.3 after surgery (P = 0.007). Laryngeal advancement surgery did not significantly improve the dysphagia scores in the moderate model (P = 0.5). Conclusions: Laryngeal advancement surgery may improve swallowing and reduce aspiration in horses affected with diseases that cause pharyngeal dysphagia.
Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate du... more Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced. That the thyrohyoid muscles play an important role in the stability of the laryngo-palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise. Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham-treatment (n = 5), or after restoration of function of the thyrohyoid muscles with surgical sutures (prosthesis-treatment, n = 6). During trials, the following determinations were made: videoendoscopy of the upper airway, gait frequency and pharyngeal and tracheal static pressures. None of the 10 horses developed DDSP during 2 separate treadmill-exercise trials under the control conditions. Seven of the 10 horses developed DDSP after resection of the TH muscles, 4 of 5 of these horses still experienced DDSP after sham-treatment, but 5 of 6 horses no longer experienced DDSP at exercise after the prosthesis-treatment. There were significant anomalies in airway pressures, respiratory frequency, and occurrence of DDSP in both the TH resection and sham-treatment conditions compared to control conditions. In contrast, no statistical differences were noted in any of the parameters measured between the prosthesis-treatment and control conditions. That the function of the TH muscles is important to the stability of the laryngo-palatal relationship and plays a role in the pathophysiology of exercise-induced DDSP. Management of horses with DDSP could be enhanced by restoring the function of the TH muscles.
<p>Screw length 1.4 mm with 1.5 turns; screw diameter 1.6 mm; screw surface area 7.2 mm<... more <p>Screw length 1.4 mm with 1.5 turns; screw diameter 1.6 mm; screw surface area 7.2 mm<sup>2</sup>. Screw is Eligiloy with Iridium oxide coat. Total electrode length 580 mm.</p
Reasons for performing study: Early detection of recurrent laryngeal neuropathy (RLN) is of consi... more Reasons for performing study: Early detection of recurrent laryngeal neuropathy (RLN) is of considerable interest to the equine industry. Objectives: To describe two imaging modalities, transoesophageal ultrasound (TEU) and computed tomography (CT) with multiplanar reconstruction to assess laryngeal muscle geometry, and determine the relationship between cricoarytenoid dorsalis (CAD) geometry and function. Study design: Two-phase study evaluating CAD geometry in experimental horses and horses with naturally occurring RLN. Methods: Equine CAD muscle volume was determined from CT scan sets using volumetric reconstruction with LiveWire. The midbody and caudal dorsal-ventral thickness of the CAD muscle was determined using a TEU in the same horses; and in horses with a range of severity of RLN (n = 112). Results: Transoesophageal ultrasound was able to readily image the CAD muscles and lower left:right CAD thickness ratios were observed with increasing disease severity. Computed tomography based muscle volume correlated very closely with ex vivo muscle volume (R 2 = 0.77). Conclusions: Computed tomography reconstruction can accurately determine intrinsic laryngeal muscle geometry. A relationship between TEU measurements of CAD geometry and laryngeal function was established. These imaging techniques could be used to track the response of the CAD muscle to restorative surgical treatments such as nerve muscle pedicle graft, nerve anastomosis and functional electrical stimulation.
Reason for performing study: Examination of the equine upper airway during racing has not previou... more Reason for performing study: Examination of the equine upper airway during racing has not previously been documented. Objective: To describe the feasibility and appearance of the upper airways by overground respiratory endoscopic examination during racing conditions. Methods: Overground videoendoscopic examinations were performed on 46 Standardbred racehorses during qualifying races. Examined horses' speeds were recorded throughout the race with a portable GPS device. Results: The procedure did not interfere with performance as there were no significant differences in race times between races in which horses were examined with the endoscope in place and prior unexamined races. Airway obstructions during or after the race were documented in 21 horses. Most previously reported causes of upper airway obstruction were observed; surprisingly bilateral ventro-medial arytenoid displacement (VMAD; n = 5) was seen during exercise as frequently as dorsal displacement of the soft palate (DDSP). Although DDSP (n = 10) was the most common diagnosis made, many displacements (n = 5) occurred after the race. Horses that demonstrated DDSP after the race had slower speeds than unaffected horses during the race. Conclusions: Racing endoscopy permits the diagnosis of upper airway obstructions without affecting performance. The occurrence of DDSP immediately after exercise may be clinically relevant. During racing VMAD may be an important anomaly. Potential relevance: Racing endoscopy could be used to correlate the sensitivity of diagnostic endoscopy during race-training or treadmill examination. The pathogenesis and significance of VMAD deserves further investigation.
Introduction: The aetiology of equine arytenoid chondrosis (chondropathy) is not clear. Trauma or... more Introduction: The aetiology of equine arytenoid chondrosis (chondropathy) is not clear. Trauma or infection/inflammation of the corniculate process and arytenoid cartilage from mucosal damage have been suggested. We aimed to describe the lesion and to develop a grading system that would correlate the size of the affected arytenoid cartilage with the degree of cartilage loss. This would facilitate a less invasive arytenoidectomy and optimization of the current therapy with restoration of a good athletic capacity of the horses. Materials and Methods: Nineteen diseased arytenoids from horses that had previous antibiotic therapy and four controls were sectioned and measured (area) at the same level, caudal to the corniculate process. All tissues were stained with HE, Safranin O and Alcian blue and evaluated histologically. Total gross area, percentage of cartilage loss and medial growth were assessed and correlated. Results: The lesions were composed of a central area of fibrosis (73.6% of cases) with dropout (47.3%), and for most cases, one or more sinus tracts communicating with the mucosa. Other significant histological features in order of frequency were: muscle involvement (84.2%), epithelial hyperplasia (68.4%), ulceration (26.3%), vascular changes (tortuous blood vessels, 26.3%) or bone metaplasia (10.5%). There was a positive correlation between gross area and medial growth (P !0.05). Cartilage loss correlated positively with epithelial hyperplasia and ulceration (P !0.05). Medial growth correlated positively with presence of pigment (P !0.05). Conclusions: We propose that epithelial hyperplasia, ulceration, medial growth and cartilage loss are accurate predictors of disease severity in equine arytenoid chondropathy and that this will help surgical intervention strategies.
Locoregional anaesthetic techniques can facilitate certain surgeries being performed under standi... more Locoregional anaesthetic techniques can facilitate certain surgeries being performed under standing procedural sedation. The second and third spinal cervical nerves (C2, C3) are part of the cervical plexus and provide sensory innervation to the peri-laryngeal structures in people; block of these nerves might permit laryngeal lateralisation surgery in horses. To describe the anatomical basis for an ultrasound-guided cervical plexus block in horses. To compare this block with conventional local anaesthetic tissue infiltration in horses undergoing standing prosthetic laryngoplasty. Cadaveric study followed by a double-blinded prospective clinical trial. A fresh equine cadaver was dissected to characterise the distribution of C2 and C3 to the perilaryngeal structures on the left side. A second cadaver was utilised to correlate ultrasound images with the previously identified structures; a tissue marker was injected to confirm the feasibility of an ultrasound-guided approach to the cervi...
The version presented here may differ from the published version or from the version of the recor... more The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.
Objective: To evaluate the efficacy of various treatments for dysphagia after laryngeal surgery. ... more 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.
the dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's resp... more the dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (psA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified "subclinical" subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically. Horses are highly developed athletes, able to reach a maximum speed approaching 88 Km/h with a maximal oxygen consumption of 200 ml/kg/min 1. Despite marked cardiovascular and musculoskeletal adaptations, the respiratory system represents a common limiting factor for oxygen delivery and athletic performance 1-3. Dilation of the rima glottis during exercise is a key, often rate limiting component of the upper airway patency and is maintained by contraction of the sole arytenoid abductor, the dorsal cricoarytenoid (DCA) muscle 1,4. The most common cause of dysfunction of the equine DCA muscle, and reduced athletic performance, is Recurrent Laryngeal Neuropathy (RLN). This disease is characterized by loss of large, alpha myelinated nerve fibers in (predominantly) the left distal recurrent laryngeal nerve (RLn) 5-9. The majority of the histological changes detected (Büngner bands, regenerating clusters, paranodal evaginations, and spheroids) are associated with primary axonal dysfunction and pathological features usually associated with primary myelinopathies (onion bulbs and demyelination), but that also occur in primary axonopathies (for the most recent review, see Draper and Piercy, 2018) 10. The aim of this study was to conduct a comprehensive electrodiagnostic study of the DCA muscles and recurrent laryngeal nerves to gather normative data in horses with normal laryngeal function at rest and during exercise. We performed needle electromyographic evaluation of the left and right DCA muscles during spontaneous breathing and following electrical stimulation of the RLn, with measurement of nerve conduction velocities bilaterally.
Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of ... more Exercise induced intermittent dorsal displacement of the soft palate (DDSP) is a common cause of airway obstruction and poor performance in racehorses. The definite etiology is still unclear, but through an experimental model, a role in the development of this condition was identified in the dysfunction of the thyro-hyoid muscles. The present study aimed to elucidate the nature of this dysfunction by investigating the spontaneous response to exercise of the thyro-hyoid muscles in racehorses with naturally occurring DDSP. Intramuscular electrodes were implanted in the thyro-hyoid muscles of nine racehorses, and connected to a telemetric unit for electromyographic monitoring implanted subcutaneously. The horses were recruited based on upper airway function evaluated through wireless endoscopy during exercise. Five horses, with normal function, were used as control; four horses were diagnosed as DDSP-affected horses based on repeated episodes of intermittent dorsal displacement of the soft palate. The electromyographic activity of the thyro-hyoid muscles recorded during incremental exercise tests on a high-speed treadmill was analyzed to measure the mean electrical activity and the median frequency of the power spectrum, thereafter subjected to wavelet decomposition. The affected horses had palatal instability with displacement on repeated exams prior to surgical implantation. Although palatal instability persisted after surgery, only two of these horses displaced the palate after instrumentation. The electromyographic traces from this group of four horses showed, at highest exercise intensity, a decrease in mean electrical activity and median power frequency, with progressive decrease in the contribution of the high frequency wavelets, consistent with development of thyro-hyoid muscle fatigue. The results of this study identified fatigue as the main factor leading to exercise induced palatal instability and DDSP in a group of racehorses. Further studies are required to evaluate the fiber type composition and metabolic characteristics of the thyro-hyoid muscles that could predispose to fatigue.
Reasons for performing study: Pharyngeal dysphagia is a debilitating, sometimes fatal condition i... more Reasons for performing study: Pharyngeal dysphagia is a debilitating, sometimes fatal condition in horses, with multiple aetiologies. The pathophysiology is complex and not fully understood. Treatment is largely supportive. Laryngeal advancement surgery may diminish symptoms of dysphagia and improve swallowing in affected horses. Objectives: 1) to induce reversible moderate and marked pharyngeal dysphagia by regional anaesthesia of branches of the glossopharyngeal (IX), vagus (X) and hypoglossal (XII) nerves; 2) to characterise the dysphagia produced by each model; and 3) to determine whether laryngeal advancement surgery improves swallowing in these models. Study design: Experimental design using 6 adult horses. Methods: Two dysphagia models were produced by blocking IX, the pharyngeal branch of X and XII unilaterally (moderate model) and only the pharyngeal branch of X bilaterally (marked model) within the guttural pouches. Both models were performed on each horse before and after surgery in order to assess the effectiveness of the surgical procedure as a potential treatment for pharyngeal dysphagia. Dysphagia was scored by partly blinded observers on a scale of 0-12 based on observations of eating (nonblinded), endoscopic examinations and fluoroscopic swallowing (blinded), where 0 = normal swallow and 12 = severe dysphagia with tracheal aspiration. Data were analysed by 3-factor ANOVA, with significance taken as P<0.05. Results: Dysphagia models were reversible, and horses swallowed normally within 3 h of model induction. The marked dysphagia model impaired movement of feed from the base of the tongue to the oesophagus and caused severe airway contamination. The average dysphagia score (mean ± s.d.) for the marked dysphagia model was 10.6 ± 1.1 before surgery and 6.1 ± 4.3 after surgery (P = 0.007). Laryngeal advancement surgery did not significantly improve the dysphagia scores in the moderate model (P = 0.5). Conclusions: Laryngeal advancement surgery may improve swallowing and reduce aspiration in horses affected with diseases that cause pharyngeal dysphagia.
Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate du... more Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced. That the thyrohyoid muscles play an important role in the stability of the laryngo-palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise. Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham-treatment (n = 5), or after restoration of function of the thyrohyoid muscles with surgical sutures (prosthesis-treatment, n = 6). During trials, the following determinations were made: videoendoscopy of the upper airway, gait frequency and pharyngeal and tracheal static pressures. None of the 10 horses developed DDSP during 2 separate treadmill-exercise trials under the control conditions. Seven of the 10 horses developed DDSP after resection of the TH muscles, 4 of 5 of these horses still experienced DDSP after sham-treatment, but 5 of 6 horses no longer experienced DDSP at exercise after the prosthesis-treatment. There were significant anomalies in airway pressures, respiratory frequency, and occurrence of DDSP in both the TH resection and sham-treatment conditions compared to control conditions. In contrast, no statistical differences were noted in any of the parameters measured between the prosthesis-treatment and control conditions. That the function of the TH muscles is important to the stability of the laryngo-palatal relationship and plays a role in the pathophysiology of exercise-induced DDSP. Management of horses with DDSP could be enhanced by restoring the function of the TH muscles.
<p>Screw length 1.4 mm with 1.5 turns; screw diameter 1.6 mm; screw surface area 7.2 mm<... more <p>Screw length 1.4 mm with 1.5 turns; screw diameter 1.6 mm; screw surface area 7.2 mm<sup>2</sup>. Screw is Eligiloy with Iridium oxide coat. Total electrode length 580 mm.</p
Reasons for performing study: Early detection of recurrent laryngeal neuropathy (RLN) is of consi... more Reasons for performing study: Early detection of recurrent laryngeal neuropathy (RLN) is of considerable interest to the equine industry. Objectives: To describe two imaging modalities, transoesophageal ultrasound (TEU) and computed tomography (CT) with multiplanar reconstruction to assess laryngeal muscle geometry, and determine the relationship between cricoarytenoid dorsalis (CAD) geometry and function. Study design: Two-phase study evaluating CAD geometry in experimental horses and horses with naturally occurring RLN. Methods: Equine CAD muscle volume was determined from CT scan sets using volumetric reconstruction with LiveWire. The midbody and caudal dorsal-ventral thickness of the CAD muscle was determined using a TEU in the same horses; and in horses with a range of severity of RLN (n = 112). Results: Transoesophageal ultrasound was able to readily image the CAD muscles and lower left:right CAD thickness ratios were observed with increasing disease severity. Computed tomography based muscle volume correlated very closely with ex vivo muscle volume (R 2 = 0.77). Conclusions: Computed tomography reconstruction can accurately determine intrinsic laryngeal muscle geometry. A relationship between TEU measurements of CAD geometry and laryngeal function was established. These imaging techniques could be used to track the response of the CAD muscle to restorative surgical treatments such as nerve muscle pedicle graft, nerve anastomosis and functional electrical stimulation.
Reason for performing study: Examination of the equine upper airway during racing has not previou... more Reason for performing study: Examination of the equine upper airway during racing has not previously been documented. Objective: To describe the feasibility and appearance of the upper airways by overground respiratory endoscopic examination during racing conditions. Methods: Overground videoendoscopic examinations were performed on 46 Standardbred racehorses during qualifying races. Examined horses' speeds were recorded throughout the race with a portable GPS device. Results: The procedure did not interfere with performance as there were no significant differences in race times between races in which horses were examined with the endoscope in place and prior unexamined races. Airway obstructions during or after the race were documented in 21 horses. Most previously reported causes of upper airway obstruction were observed; surprisingly bilateral ventro-medial arytenoid displacement (VMAD; n = 5) was seen during exercise as frequently as dorsal displacement of the soft palate (DDSP). Although DDSP (n = 10) was the most common diagnosis made, many displacements (n = 5) occurred after the race. Horses that demonstrated DDSP after the race had slower speeds than unaffected horses during the race. Conclusions: Racing endoscopy permits the diagnosis of upper airway obstructions without affecting performance. The occurrence of DDSP immediately after exercise may be clinically relevant. During racing VMAD may be an important anomaly. Potential relevance: Racing endoscopy could be used to correlate the sensitivity of diagnostic endoscopy during race-training or treadmill examination. The pathogenesis and significance of VMAD deserves further investigation.
Introduction: The aetiology of equine arytenoid chondrosis (chondropathy) is not clear. Trauma or... more Introduction: The aetiology of equine arytenoid chondrosis (chondropathy) is not clear. Trauma or infection/inflammation of the corniculate process and arytenoid cartilage from mucosal damage have been suggested. We aimed to describe the lesion and to develop a grading system that would correlate the size of the affected arytenoid cartilage with the degree of cartilage loss. This would facilitate a less invasive arytenoidectomy and optimization of the current therapy with restoration of a good athletic capacity of the horses. Materials and Methods: Nineteen diseased arytenoids from horses that had previous antibiotic therapy and four controls were sectioned and measured (area) at the same level, caudal to the corniculate process. All tissues were stained with HE, Safranin O and Alcian blue and evaluated histologically. Total gross area, percentage of cartilage loss and medial growth were assessed and correlated. Results: The lesions were composed of a central area of fibrosis (73.6% of cases) with dropout (47.3%), and for most cases, one or more sinus tracts communicating with the mucosa. Other significant histological features in order of frequency were: muscle involvement (84.2%), epithelial hyperplasia (68.4%), ulceration (26.3%), vascular changes (tortuous blood vessels, 26.3%) or bone metaplasia (10.5%). There was a positive correlation between gross area and medial growth (P !0.05). Cartilage loss correlated positively with epithelial hyperplasia and ulceration (P !0.05). Medial growth correlated positively with presence of pigment (P !0.05). Conclusions: We propose that epithelial hyperplasia, ulceration, medial growth and cartilage loss are accurate predictors of disease severity in equine arytenoid chondropathy and that this will help surgical intervention strategies.
Locoregional anaesthetic techniques can facilitate certain surgeries being performed under standi... more Locoregional anaesthetic techniques can facilitate certain surgeries being performed under standing procedural sedation. The second and third spinal cervical nerves (C2, C3) are part of the cervical plexus and provide sensory innervation to the peri-laryngeal structures in people; block of these nerves might permit laryngeal lateralisation surgery in horses. To describe the anatomical basis for an ultrasound-guided cervical plexus block in horses. To compare this block with conventional local anaesthetic tissue infiltration in horses undergoing standing prosthetic laryngoplasty. Cadaveric study followed by a double-blinded prospective clinical trial. A fresh equine cadaver was dissected to characterise the distribution of C2 and C3 to the perilaryngeal structures on the left side. A second cadaver was utilised to correlate ultrasound images with the previously identified structures; a tissue marker was injected to confirm the feasibility of an ultrasound-guided approach to the cervi...
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