“He just doesn’t finish.”

“She feels strong at first, but something changes when the work gets harder.”

“He makes a noise when he breathes.”

Changes like these can prompt questions about fitness, training or soundness. They can also be signs that a horse’s upper airway is limiting breathing during exercise.

Upper airway problems in horses include roaring, soft palate displacement, epiglottic entrapment and collapse of the throat’s flexible walls. These conditions can narrow the breathing passage during exercise, leading to unusual breathing sounds, reduced stamina or sudden changes in performance. Some are visible at rest; others require a camera examination while the horse works.

This guide explains the main obstructive upper airway conditions in language owners can use when discussing their horse with a veterinarian. It focuses on breathing mechanics during exercise, rather than infections such as strangles or equine influenza.

How the Equine Upper Airway Works

Horses are obligate nasal breathers: air normally enters through the nostrils and passes through the nasal passages, pharynx and larynx before traveling down the trachea to the lungs. The pharynx is the throat passage behind the nose and mouth. The larynx, or voice box, is the cartilaginous and muscular structure that controls the entrance to the windpipe.

The soft palate is a flexible sheet of tissue separating the mouth from the nasal part of the throat. During normal breathing, its back edge lies beneath the epiglottis, a leaf-shaped cartilage at the entrance to the voice box. This relationship helps maintain the horse’s nasal breathing route.

During exercise, the nostrils dilate and the larynx opens wider. Muscles help maintain the shape of flexible airway structures as airflow increases. A horse needs both sufficient space for air to pass and the ability to keep that space open during each breath.

Inspiration creates pressure below atmospheric pressure inside the airway. This draws air toward the lungs, but it can also draw susceptible tissues inward. If those tissues narrow the passage, resistance increases and breathing requires more effort.

Common Upper Airway Conditions

1Roaring in horses or recurrent laryngeal neuropathy

Recurrent laryngeal neuropathy, often called RLN or roaring, involves degeneration of the nerve supply to muscles of the larynx. It predominantly affects the left side. Weakness or paralysis can prevent one of the paired cartilages at the entrance to the windpipe—the arytenoid cartilages—from opening fully and staying open as the horse breathes in.

This can narrow the entrance to the windpipe. During demanding exercise, the affected cartilage and associated tissues may move further into the airflow. The result can be increased inspiratory resistance and reduced exercise capacity.

A roaring or whistling sound may be the first sign an owner notices. A horse may also struggle to sustain demanding exercise. Endoscopy, an examination using a small flexible camera, shows how the voice box moves. Viewing it during exercise can establish whether it stays sufficiently open when the horse is working.

Management depends on functional severity and athletic requirements. Some horses undergo prosthetic laryngoplasty, commonly called a tie-back, which holds the affected cartilage in a more open position. An additional procedure may address tissue associated with the vocal fold. The objective is to improve airflow while considering swallowing function and the demands of the horse’s intended activity.

2Soft palate displacement in horses or DDSP

Dorsal displacement of the soft palate, abbreviated DDSP, occurs when the back edge of the soft palate moves above the epiglottis. During exercise, this changes the normal relationship between these structures and can obstruct airflow, particularly during expiration.

The horse may produce a gurgling sound or show a sudden reduction in performance. Intermittent displacement can disappear when exercise stops, so a resting examination may not reveal the problem.

The muscles and nerves supporting the throat, the position of the voice box and the shape of the epiglottis can all be relevant. Palatal instability means the soft palate becomes unusually mobile during breathing. It may occur before displacement, although it does not always progress to DDSP.

Muscle fatigue is one contributor supported by research. A small study of nine racehorses found electrical activity consistent with fatigue in muscles that help position the voice box in the group with a history of palatal instability and DDSP. This helps explain how support may change during demanding exercise, although the causes of DDSP differ between horses.

Once the palate has displaced, it can interfere particularly with breathing out. Watching the sequence during exercise helps the veterinarian distinguish instability from the obstruction caused by displacement.

Exercising endoscopy helps establish whether displacement occurs when the horse’s signs develop. Management is individualized and may include addressing identified inflammation or contributing factors, changes in exercise management, or a selected surgical procedure. A laryngeal tie-forward is one surgical option. It moves the voice box forward and upward to improve its relationship with the soft palate.

3Epiglottic entrapment

Epiglottic entrapment occurs when a fold of tissue beneath the epiglottis folds upward and covers it. This tissue is an extension of the aryepiglottic folds, which connect the epiglottis with other structures around the voice box. A camera examination shows the epiglottis covered by this membrane.

Entrapment can be persistent or intermittent. It may be associated with abnormal respiratory noise or exercise intolerance, although the importance of the finding varies between horses. Inflammation, tissue changes and concurrent abnormalities can influence the clinical picture.

Endoscopy identifies the entrapment and allows assessment for other problems. Treatment commonly involves surgically dividing the entrapping tissue. The technique depends on the appearance of that tissue and the individual case.

Recovery depends partly on whether another airway problem is present and whether complications develop. A 2024 study of surgically treated racehorses found that postoperative airway complications and repeat entrapment were associated with a lower likelihood of racing afterward. Follow-up therefore considers the whole airway as well as the treated tissue.

4Pharyngeal collapse and other causes of airway narrowing

The throat’s flexible walls rely on muscular support to stay open. If that support cannot withstand the pressure generated as the horse breathes in, the walls can move inward and narrow the passage. This is called pharyngeal or nasopharyngeal collapse. It can affect different parts of the passage and may appear only under particular exercise conditions.

Other tissues can also move into the breathing passage, including the aryepiglottic folds around the epiglottis and the vocal folds within the voice box. These changes can occur alone or alongside soft palate or laryngeal problems.

The effect on the horse depends on how much the passage narrows, when it happens and whether it matches the signs the rider notices.

Exercising endoscopy is particularly useful for these conditions. Management depends on the structures involved, associated findings and the horse’s intended work. Nasopharyngeal collapse can be difficult to manage, and there is no reliably effective treatment for every affected horse. The degree of narrowing and the horse’s intended activity guide the discussion.

Signs of Upper Airway Problems

Possible signs include new respiratory noise during work, an unexplained loss of speed or stamina, an abrupt change in effort, and difficulty sustaining a level of exercise the horse previously managed comfortably. Some riders notice a change only at a particular speed, late in a session or in a particular head and neck position.

These observations are useful clues, but they are not specific diagnoses. Pain, conditioning, cardiac disease, lower airway disease and other problems can produce overlapping performance changes.

Respiratory noise does not tell the whole story

Roaring, whistling, fluttering or gurgling may draw attention to the airway. The sound depends on which tissues are moving and how air passes them. Loudness alone does not reliably establish the degree of obstruction or its effect on performance.

What to tell your veterinarian

Describe when the change starts, whether it occurs consistently, and whether it relates to speed, duration, turns, collection or recovery. A video with clear audio can be useful. Note recent respiratory illness, coughing, discharge and changes in training or tack.

These details help the veterinarian choose an examination that reflects what your horse is experiencing.

Why More Than One Condition May Be Present

Finding one abnormality does not necessarily explain the entire problem. In a study of 600 Thoroughbred racehorses examined on a high-speed treadmill, complex obstruction involving more than one structure occurred in 30% of horses with upper respiratory tract obstruction.

A more recent study examined 164 barrel horses referred for respiratory signs or poor performance. Among the 140 horses found to have an obstruction, 56% had two or more abnormalities. These studies describe horses undergoing clinical investigation, so their percentages should not be applied to the entire horse population.

For an owner, the practical lesson is that the first finding may not explain everything. The veterinarian looks at all the affected structures and how they behave together. Correcting one problem may improve breathing while another still needs attention.

The relationship with the lungs

Upper and lower airway conditions may coexist. Equine asthma affects the lower airways and can contribute to exercise intolerance. Exercise-induced pulmonary hemorrhage, or EIPH, involves bleeding within the lungs during exercise. Both affect a different part of the breathing system from the throat conditions described above.

There is evidence that inflammation and upper airway stability can be related. In a study of 129 ridden sport horses, lower-airway inflammation and enlargement of lymphoid tissue in the throat were associated with pharyngeal instability. That finding supports looking for inflammation when investigating an unstable airway; it does not establish the same relationship for every upper airway condition.

Depending on the horse’s signs, assessment may therefore include the lungs as well as the throat. Identifying and managing each contributing problem gives the veterinarian a more complete picture of what is limiting breathing.

How Airway Conditions Are Diagnosed

Resting examination

Assessment begins with the history and a physical examination. Resting endoscopy allows the veterinarian to view structures inside the upper airway, assess laryngeal movement and identify abnormalities such as persistent epiglottic entrapment. Additional examination or imaging may be appropriate for particular findings.

A normal resting appearance is useful information, but it cannot exclude a problem that develops only during work.

Exercising endoscopy

Dynamic or exercising endoscopy uses a small camera passed through a nostril to record the throat while the horse works. With an overground system, the horse can be examined during ridden or driven exercise. A treadmill examination is another option. The veterinarian chooses the approach best suited to the problem.

The exercise should reflect the circumstances associated with the problem as closely as practical. Speed, duration, rider influence and head and neck position can matter. Research in ridden sport horses found that head flexion and rider interaction could worsen instability in affected horses.

The recording allows the veterinarian to examine when an abnormality begins, which structures are involved and whether multiple changes occur together. It also helps connect the findings with the rider’s observations. A test that does not reproduce the relevant effort may leave an intermittent problem unresolved.

Management and the Individual Horse

A diagnosis provides a starting point. Decisions also depend on the severity and timing of obstruction, concurrent disease, the horse’s athletic demands and the expected benefits and limitations of available treatments.

Management may include treating identified inflammation, adjusting training or equipment factors, performing a procedure to correct a particular abnormality, and checking the response afterward. Your veterinarian can explain what each part of the plan is intended to achieve.

Why athletic demands matter

A racehorse sustaining speed, an event horse completing cross-country and a barrel horse accelerating through a short pattern face different demands. Jumping, dressage and other ridden work may also involve particular head and neck positions that need to be represented during investigation.

These differences help shape the examination. The diagnosis comes from assessing the individual horse under relevant conditions.

Two horses with the same diagnosis may therefore need different plans. What matters is how the condition affects your horse during its work, and whether that work remains appropriate.

Evaluating the outcome

Follow-up should consider the original problem: whether the horse can sustain the intended effort, whether the clinical signs have changed and whether further examination is needed. Reduced noise alone may not capture the full outcome.

Persistent difficulties after treatment are a reason to reassess the horse, including other possible airway findings and nonrespiratory causes of poor performance.

Frequently Asked Questions