Pharynx
The pharynx is a muscular funnel connecting the oral and nasal cavities to the esophagus and larynx. In the horse the soft palate is unusually long and normally rests below the epiglottis. This arrangement seals the oral airway except during swallowing, which means horses are obligate nasal breathers and cannot breathe through the mouth under normal circumstances. The pharyngeal muscles coordinate the complex swallowing reflex that directs food to the esophagus while protecting the airway. During exercise the pharynx must remain widely patent under high airflow demands.
Dorsal displacement of the soft palate, pharyngeal collapse, and other dynamic upper-airway conditions are common causes of exercise intolerance and abnormal respiratory noise. Diagnosis often requires dynamic endoscopy. Conditions that affect the pharynx can rapidly compromise breathing because of obligate nasal breathing.
## Overview Epiglottic entrapment occurs when the aryepiglottic fold envelops the epiglottis, restricting its movement. It can cause respiratory noise, exercise intolerance, or abnormal swallowing an
## Overview Arytenoid chondropathy is the pathologic enlargement and deformation of one or both arytenoid cartilages, most often the end result of arytenoid chondritis. The enlarged cartilage cannot
## Overview Pharyngeal lymphoid hyperplasia is enlargement of the lymphoid tissue in the pharynx, common in young horses. It is usually a response to antigenic stimulation and is self-limiting. Signs
## Overview Guttural pouch mycosis is a fungal infection (usually Aspergillus) of the guttural pouch. Fungal plaques commonly form over major arteries. Erosion of the vessel wall causes potentially f
## Overview Dorsal displacement of the soft palate (DDSP) is intermittent obstruction of the upper airway during exercise caused by the soft palate moving dorsal to the epiglottis. It is a leading ca
## Overview A pharyngeal abscess is a collection of pus in the retropharyngeal lymph nodes, most often secondary to Streptococcus equi (strangles). It causes difficulty swallowing, nasal discharge, s
## Overview Fourth branchial arch defect (also called laryngeal dysplasia or 4-BAD) is a congenital malformation of laryngeal structures derived from the fourth branchial arch. It most often affects
Recurrent laryngeal neuropathy (RLN), commonly known as roaring or whistling, is a progressive degeneration of the recurrent laryngeal nerves, mainly affecting the left side and reducing or preventing
Abnormal respiratory noise during exercise, especially with poor performance, should be evaluated. Horses that appear to be choking or have difficulty swallowing need immediate attention.
## Overview Epiglottic entrapment occurs when the aryepiglottic fold envelops the epiglottis, restricting its movement. It can cause respiratory noise, exercise intolerance, or abnormal swallowing and is diagnosed by endoscopy. ## Causes Congenital redundancy of the aryepiglottic tissue or acquired inflammation/scarring. ## Diagnosis Resting or exercising endoscopy showing the epiglottis covered by the fold. ## Treatment Surgical axial division of the entrapping fold, often performed standing or under general anesthesia. Prognosis is generally good. ## Recovery and Prognosis Good for uncomplicated cases. Recurrence is uncommon after complete division. ## Prevention None specific. Signs include: respiratory noise; exercise intolerance; abnormal swallowing; visible on endoscopy
## Overview Arytenoid chondropathy is the pathologic enlargement and deformation of one or both arytenoid cartilages, most often the end result of arytenoid chondritis. The enlarged cartilage cannot abduct normally, producing upper-airway obstruction. The term is sometimes used interchangeably with arytenoid chondritis; chondropathy emphasizes the structural deformity rather than the active inflammatory process. ## Causes The same mucosal trauma and secondary infection hypothesized for chondritis lead to cartilage necrosis, fibrosis, and permanent enlargement. Granulation tissue may protrude into the airway lumen. ## Diagnosis Endoscopic examination shows a thickened, misshapen arytenoid with reduced mobility and often axial granulation tissue. Ultrasound assesses the full thickness of the cartilage. Clinical signs mirror those of recurrent laryngeal neuropathy. ## Treatment Medical therapy (antibiotics, anti-inflammatories, airway rest) is appropriate only for early lesions. Established chondropathy usually requires partial arytenoidectomy or permanent tracheostomy in severe bilateral cases. ## Recovery and Prognosis Prognosis after unilateral arytenoidectomy is fair to good for return to athletic use. Bilateral disease or extensive peri-laryngeal fibrosis worsens the outlook. ## Prevention Identical to arytenoid chondritis; no specific measures are proven. Signs include: inspiratory noise; exercise intolerance; enlarged immobile arytenoid on endoscopy; respiratory distress in advanced cases
## Overview Pharyngeal lymphoid hyperplasia is enlargement of the lymphoid tissue in the pharynx, common in young horses. It is usually a response to antigenic stimulation and is self-limiting. Signs include cough, nasal discharge, and mild exercise intolerance. Most horses outgrow it. ## Causes Immune stimulation from environmental antigens or mild respiratory challenge in young horses. ## Diagnosis Endoscopy showing enlarged lymphoid follicles in the pharynx. ## Treatment Usually none required. Environmental management and time. Anti-inflammatories if the horse is clinically affected. ## Recovery and Prognosis Excellent. Most resolve as the horse matures. ## Prevention Good air quality in stables. Signs include: cough; nasal discharge; mild exercise intolerance; enlarged lymphoid follicles on endoscopy; usually self-limiting
## Overview Guttural pouch mycosis is a fungal infection (usually Aspergillus) of the guttural pouch. Fungal plaques commonly form over major arteries. Erosion of the vessel wall causes potentially fatal nosebleeds. Dysphagia and cranial-nerve deficits also occur. ## Causes Aspergillus infection. Predisposing factors are unclear. ## Diagnosis Endoscopy showing fungal plaques, often over the internal carotid or other arteries. History of epistaxis is highly suggestive. ## Treatment Occlusion of the affected artery (coil or balloon embolization) to prevent fatal hemorrhage, plus topical antifungal medication. Medical treatment alone is slow and less reliable for preventing bleeds. ## Recovery and Prognosis Guarded. Successful arterial occlusion prevents fatal hemorrhage in many cases. Neurologic deficits may persist. ## Prevention None specific. Signs include: epistaxis (can be fatal); nasal discharge; difficulty swallowing; cranial nerve deficits
## Overview Dorsal displacement of the soft palate (DDSP) is intermittent obstruction of the upper airway during exercise caused by the soft palate moving dorsal to the epiglottis. It is a leading cause of respiratory noise and poor performance in racehorses and other high-speed athletes. ## Causes Neuromuscular dysfunction, inflammation, or fatigue of the muscles that stabilize the palate and larynx. ## Diagnosis Dynamic endoscopy during exercise. ## Treatment Conservative measures or surgery (tie-forward has higher reported success than myectomy in many series). ## Recovery and Prognosis Variable but often favorable with appropriate intervention. ## Prevention Control of lower-airway inflammation and fitness management. Signs include: gurgling respiratory noise during exercise; sudden exercise intolerance; choking down at speed
## Overview A pharyngeal abscess is a collection of pus in the retropharyngeal lymph nodes, most often secondary to Streptococcus equi (strangles). It causes difficulty swallowing, nasal discharge, swelling between the jaws, fever, and an extended head-and-neck posture. Large abscesses can compress the airway. ## Causes Bacterial infection, predominantly Streptococcus equi subspecies equi. ## Diagnosis Clinical signs, endoscopy, ultrasound of the retropharyngeal region, and culture. ## Treatment Antibiotics in selected cases, anti-inflammatories, and drainage when the abscess is mature and accessible. Airway support if compression occurs. ## Recovery and Prognosis Good for most external or drainable abscesses. Complications include guttural pouch empyema or bastard strangles. ## Prevention Strangles biosecurity and vaccination where appropriate. Signs include: difficulty swallowing; nasal discharge; swelling between the mandibles; extended head and neck; fever
## Overview Fourth branchial arch defect (also called laryngeal dysplasia or 4-BAD) is a congenital malformation of laryngeal structures derived from the fourth branchial arch. It most often affects the right side and can cause respiratory noise, exercise intolerance, or dysphagia from birth. ## Causes Developmental failure of cartilage and muscle formation (thyroid and cricoid cartilages, associated muscles). ## Diagnosis Endoscopy showing reduced arytenoid abduction or rostral displacement of the palatopharyngeal arch, plus ultrasound, radiographs, or computed tomography confirming cartilage abnormalities. ## Treatment Surgical options are limited and case-dependent. Some horses are managed conservatively if signs are mild. Severe dysphagia or airway obstruction may require more aggressive intervention. ## Recovery and Prognosis Variable. Mild cases may perform adequately. Severe defects limit athletic use or cause ongoing dysphagia. ## Prevention None (congenital). Signs include: respiratory noise from birth; dysphagia or nasal return of milk in foals; exercise intolerance; arytenoid dysfunction on endoscopy
Recurrent laryngeal neuropathy (RLN), commonly known as roaring or whistling, is a progressive degeneration of the recurrent laryngeal nerves, mainly affecting the left side and reducing or preventing movement of the left arytenoid cartilage. This results in reduced airway diameter during inspiration and the characteristic inspiratory noise during exercise. It is one of the most important upper airway conditions affecting performance horses. ## What it is The left recurrent laryngeal nerve has a very long course (wrapping around the aortic arch), making it more susceptible to damage than the right nerve. Progressive axonopathy leads to denervation and atrophy of the cricoarytenoideus dorsalis (CAD) muscle, the only abductor of the arytenoid cartilage. As a result, the left arytenoid fails to open fully during exercise, causing turbulent airflow and the classic roaring sound. Laryngeal function is graded I to IV on resting endoscopic examination (Havemeyer system), with higher grades indicating greater impairment of arytenoid movement. ## Signs and symptoms - Inspiratory noise ('roaring' or 'whistling') during exercise that worsens with speed and fatigue - Exercise intolerance or reduced performance - In severe cases, respiratory distress during intense work - Abnormal arytenoid movement on resting or exercising endoscopy - The noise is often absent or minimal at rest and becomes obvious only during exercise ## Causes and risk factors RLN is a distal axonopathy whose exact cause is not fully understood but has a genetic component. It is more common in larger horses (especially Thoroughbreds and drafts) and appears to have a hereditary predisposition. Risk increases with age and size. Clinical disease is predominantly left-sided; the longer left nerve is thought to contribute. ## How it is diagnosed Diagnosis is confirmed by endoscopic examination of the larynx, ideally during exercise (dynamic endoscopy) to assess arytenoid function under stress. Resting endoscopy can grade the degree of paralysis but may underestimate the severity. The Havemeyer grading system (I to IV) is used to classify the severity based on arytenoid movement and position. ## Treatment and management Treatment depends on the grade and the horse's intended use. Horses with Grade I to II laryngeal function may not require intervention. For performance horses with Grade III or IV, surgical options include laryngoplasty (tie-back procedure), in which the arytenoid is permanently fixed in an open position, often combined with ventriculocordectomy (removal of the vocal cord and ventricle). Other procedures such as arytenoidectomy are used in selected cases. Post-operative care and rehabilitation are important for success. ## When to call the vet Contact your veterinarian if your horse develops an abnormal respiratory noise during exercise or shows signs of reduced performance. Dynamic endoscopy is the best way to confirm the diagnosis and determine the appropriate treatment. ## Prevention There is no proven way to prevent RLN, but selective breeding away from affected lines may help reduce incidence over time. Endoscopic assessment of laryngeal function can help guide decisions about whether intervention is needed. ## Frequently asked questions **Can a horse with roaring still compete?** Many horses return to successful competition after laryngoplasty (tie-back), though some degree of noise may remain and results vary. **Is roaring painful?** No. RLN itself is not painful, but the reduced airway can limit performance and, in severe cases, cause respiratory distress. **Does the tie-back surgery last forever?** The surgery provides long-term improvement in most horses, but complications such as implant failure or aspiration can occur in some cases. This information is for educational purposes only. Always consult with a licensed veterinarian for diagnosis and treatment of your horse. Signs include: Inspiratory noise ('roaring' or 'whistling') during exercise that worsens with speed and fatigue; exercise intolerance or reduced performance; in severe cases, respiratory distress during intense work; abnormal arytenoid movement on resting or exercising endoscopy; noise often absent at rest and becomes obvious only during exercise
Dorsal displacement of the soft palate, pharyngeal collapse, and other dynamic upper-airway conditions are common causes of exercise intolerance and abnormal respiratory noise. Diagnosis often requires dynamic endoscopy. Conditions that affect the pharynx can rapidly compromise breathing because of obligate nasal breathing.
Abnormal respiratory noise during exercise, especially with poor performance, should be evaluated. Horses that appear to be choking or have difficulty swallowing need immediate attention.
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