Dynamic pharyngeal collapse in racehorses

Boyle, A. G.; Martin, Benson B.; Davidson, Elizabeth; Durando, Mary M.; Birks, Eric K.

doi:10.1111/j.2042-3306.2006.tb05602.x

Cited by 34 publications

(44 citation statements)

References 10 publications

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“…Nasopharyngeal collapse, which was identified in 14.0% of horses in this study (Figure 8), has been observed during DOE examinations to be a cause of respiratory noise and/or exercise intolerance in performance horses and racehorses (Boyle et al 2006;Dart et al 2001;Kannegeiter & Dore 1995;Martin et al 2000;Strand & Staempfli 1993). Studies have found NPC to occur with considerably less frequency than other dynamic abnormalities of the URT, with a prevalence of 1.3% -18.0% in racehorses examined because of respiratory noise and/or poor performance (Kannegeiter & Dore 1995;Lane et al 2006;Tan et al 2005).…”

Section: Discussionmentioning

confidence: 57%

“…It allowed detection of conditions that are not apparent during resting examinations such as palatal instability (PI) (Lane et al 2006), intermittent DDSP (Barakzai & Dixon 2011;Desmaizieres et al 2009;Lane et al 2006;Pollock et al 2009), left corniculate process collapse (LCPC) (Barakzai & Dixon 2011), axial deviation of aryepiglottic folds (ADAF) (King et al 2001), vocal cord collapse (VCC) (Barakzai & Dixon 2011) and nasopharyngeal collapse (NPC) (Boyle et al 2006;Strand & Staempfli 1993). In addition, it provided more information about arytenoid function at exercise (Barakzai & Dixon 2011;Desmaizieres et al 2009;Franklin 2008;Pollock et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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Dynamic upper respiratory abnormalities in Thoroughbred racehorses in South Africa

Mirazo¹,

Page²,

Rubio‐Martínez³

et al. 2014

J S Afr Vet Assoc

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Upper airway endoscopy at rest has been the diagnostic method of choice for equine upper respiratory tract (URT) conditions. Development of high-speed treadmill endoscopy improved the sensitivity of URT endoscopy by allowing observation of the horse’s nasopharynx and larynx during exercise. However, treadmill exercise may not always accurately represent the horse’s normal exercise as track surface, rider, tack and environmental variables are altered. Recently, the development of dynamic overground endoscopy (DOE) has addressed some of these shortcomings. A retrospective study was undertaken to describe the URT abnormalities detected during DOE in racehorses presenting with poor performance and/or abnormal respiratory noise. Patient records of Thoroughbred racehorses undergoing DOE from November 2011 to August 2012 were reviewed. Data collected included signalment, primary complaint, distance exercised, maximum speed and dynamic airway abnormalities detected. Fifty-two horses underwent DOE for investigation of poor performance and/or abnormal respiratory noise. The main abnormalities detected included axial deviation of the aryepiglottic folds (40%), vocal cord collapse (35%), abnormal arytenoid function (33%) and dorsal displacement of the soft palate (25%). A total of 40 horses were diagnosed with one or more abnormalities of the URT (77%). Fifteen horses (29%) had a single abnormality and 25 horses (48%) had multiple abnormalities. This study showed that DOE is a useful technique for investigating dynamic disorders of the URT in racehorses in South Africa. The total number and type of dynamic pathological conditions were comparable with those identified in similar populations in other geographical locations.

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Section: Discussionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Dynamic upper respiratory abnormalities in Thoroughbred racehorses in South Africa

Mirazo¹,

Page²,

Rubio‐Martínez³

et al. 2014

J S Afr Vet Assoc

View full text Add to dashboard Cite

show abstract

“…At that, grades B of submaximal abduction and C of dynamic collapse were further divided into three subgrades respectively. Axial deviation of the aryepiglottic fold (ADAF) was defined according to King et al 2001 and dynamic pharyngeal collapse (PC) according to Boyle et al 2006. Occurrence of a dorsal displacement of the soft palate (DDSP) was classified into rarely short (<3×/10 sec), often short (>3×/10 sec) and long to continuous (>8 sec) DDSP.…”

Section: Discussionmentioning

confidence: 99%

Frequencies of dynamic obstructions of the upper respiratory tract in 135 Thoroughbreds during on-board exercise endoscopy

Oellers¹,

Barton²,

Ohnesorge³

2018

PHK

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Summary:The frequencies of dynamic obstructions in thoroughbreds were investigated by performing on-board exercise endoscopy in 135 horses. 17 of these horses showed abnormal respiratory noise only and 35 solely poor performance. In 39 cases, both was reported. In addition, 44 horses underwent endoscopy without any clinical signs. In all of 56 horses that exhibited an audible abnormal respiratory noise, an obstruction of the upper respiratory tract was present. Overall, dynamic upper airway obstructions were detected in 72.6 % (98/135). The most commonly diagnosed obstruction was axial deviation of the aryepiglottic fold (ADAF) in 55.1% of horses (54/98). 24.4 % (24/98) showed palatal instability (PI), 30.6 % (30/98) dorsal displacement of the soft palate (DDSP) and 11.2 % (11/98) arytenoid cartilage collapse (ACC). Furthermore, 53.1% (52/98) of horses had abnormalities in the area of the vocal folds. Of these horses, 13 had unilateral or bilateral vocal cord collapse (VCC) and 8 displayed vibration of the vocal cords. 31 horses showed axial deviation in the area of the caudal vocal fold (ADPV) as a sole abnormality. By the new description of these ADPV, the origin of the abnormal respiratory noise in a further proportion of horses could be explained. Including ADPV, an obstruction of the upper airways was observed in all horses (100 %) with specified abnormal respiratory noise. If only horses with long or continuous (> 8 sec) DDSP were taken into account, abnormal respiratory noise was audible in 93.3 % and poor performance was present in 73.3 %. It can thus be assumed that horses with DDSP requiring treatment are clinically apparent either with abnormal respiratory noise or poor performance. Furthermore, it was demonstrated, that in 52.3% of horses without poor performance or abnormal respiratory noise an dynamic upper airway obstruction was identified.

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“…Dynamic pharyngeal collapse may lead to partial-to-complete obstruction of the airway rostral to the glottis and marked transient increases in negative pressure with each inspiration [75]. Characterised by ventral displacement of the dorsal pharyngeal wall and/or axial displacement of the lateral walls of the pharynx, the obstruction increases in severity as the number of walls involved rises from one to three, and finally to four if PI/DDSP also occurs [75].…”

Section: Some Key Attributes Of Breathing-related Functions In Thementioning

confidence: 99%

Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles

Mellor

Beausoleil

2017

Animals

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Simple SummaryHorses have superior athletic capabilities due largely to their exceptional cardiorespiratory responses during exercise. This has particular relevance to horses’ potential to experience breathlessness, especially when their athletic performance is reduced by impaired respiratory function. Breathlessness, incorporating three types of unpleasant experiences, has been noted as of significant animal welfare concern in other mammals. However, the potential for breathlessness to occur in horses as usually ridden wearing bitted bridles has not yet been evaluated in detail. Accordingly, key physiological responses to exercise and the consequences of impaired respiratory function are outlined. Then the physiological control of breathing and the generation of the aversive experiences of breathlessness are explained. Finally, the potential for horses with unimpaired and impaired respiratory function to experience the different types of breathlessness is evaluated. This information provides a basis for considering the circumstances in which breathlessness may have significant negative welfare impacts on horses as currently ridden wearing bitted bridles. Potential beneficial impacts on respiratory function of using bitless bridles are then discussed with emphasis on the underlying mechanisms and their relevance to breathlessness. It is noted that direct comparisons of cardiorespiratory responses to exercise in horses wearing bitless and bitted bridles are not available and it is recommended that such studies be undertaken.AbstractHorses engaged in strenuous exercise display physiological responses that approach the upper functional limits of key organ systems, in particular their cardiorespiratory systems. Maximum athletic performance is therefore vulnerable to factors that diminish these functional capacities, and such impairment might also lead to horses experiencing unpleasant respiratory sensations, i.e., breathlessness. The aim of this review is to use existing literature on equine cardiorespiratory physiology and athletic performance to evaluate the potential for various types of breathlessness to occur in exercising horses. In addition, we investigate the influence of management factors such as rein and bit use and of respiratory pathology on the likelihood and intensity of equine breathlessness occurring during exercise. In ridden horses, rein use that reduces the jowl angle, sometimes markedly, and conditions that partially obstruct the nasopharynx and/or larynx, impair airflow in the upper respiratory tract and lead to increased flow resistance. The associated upper airway pressure changes, transmitted to the lower airways, may have pathophysiological sequelae in the alveolae, which, in their turn, may increase airflow resistance in the lower airways and impede respiratory gas exchange. Other sequelae include decreases in respiratory minute volume and worsening of the hypoxaemia, hypercapnia and acidaemia commonly observed in healthy horses during strenuous exercise. These and other factors are implica...

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Dynamic pharyngeal collapse in racehorses

Abstract: This study provides a classification system for dynamic pharyngeal collapse and suggests that older racehorses (> or = 4 years of age) diagnosed with PC and all horses with grade 3 PC have a poor prognosis for return to previous level of performance.

Cited by 34 publications

References 10 publications

Dynamic upper respiratory abnormalities in Thoroughbred racehorses in South Africa

Dynamic upper respiratory abnormalities in Thoroughbred racehorses in South Africa

Frequencies of dynamic obstructions of the upper respiratory tract in 135 Thoroughbreds during on-board exercise endoscopy

Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles

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