What’s That Sound? Respiratory Distress in Horses

Several conditions can cause respiratory noise and distress in horses. Be vigilant, and have your horse evaluated if you notice signs.
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Dr. Sarah Gray shares an endoscopy image of a horse’s arytenoids and epiglottis.
Dr. Sarah Gray shares an endoscopy image of a horse’s arytenoids and epiglottis. | Fred Zwicky photo Courtesy University of Illinois at Urbana-Champaign College of Veterinary Medicine

Whether your horse is a racing Thoroughbred, a backyard pleasure horse, or something between, he or she needs functioning airways. So, what happens when horses make strange sounds when they breathe? Or when they cannot exercise because of breathing problems?

Sarah Gray, DVM, Dipl. ACVS-LA, a boarded equine surgeon at the University of Illinois Veterinary Teaching Hospital, in Urbana, shares her expertise on equine respiratory cases.

Take a Look Inside

“Regardless of the symptoms of the horse, evaluation by a veterinarian is definitely recommended. And, if the horse is distressed, the sooner the better,” says Gray. “Respiratory sounds you can hear without a stethoscope usually indicate an issue in the upper airway, and endoscopy is a common first step in these cases to be able to evaluate the horse.”

During an endoscopic exam, the veterinarian passes a flexible camera up the nose to the throat latch area. As the camera passes through, the veterinarian can evaluate the nasal passages, vocal cords, and structures that make up the larynx (where the nasal cavity meets the trachea) and pharynx (where the mouth meets the esophagus). These structures are often evaluated together because they are very closely associated and must coordinate with each other.

The controls used to guide the endoscope.
The controls used to guide the endoscope. | Fred Zwicky photo courtesy University of Illinois at Urbana-Champaign College of Veterinary Medicine

Athlete or Respiratory Distress?

Two populations of horses come in for evaluation of upper airway noise: athletic horses that are making noise while exercising and horses that are making noise while breathing but are in respiratory distress. The more common of the two are the athletes that make noise while intensely exercising or performing poorly. For these patients Gray says an endoscopic exam is best done without sedation, if possible, so practitioners can observe the normal movement of these structures.

As for equine athletes that come in with audible respiratory sounds, many have an anatomic abnormality causing the noise, says Gray. The veterinarian’s focus in those horses is correcting the anatomic abnormality to get the athlete back to peak performance. While any horse can have a variety of upper airway abnormalities, she adds, Standardbred racehorses often have a condition called an intermittently dorsally displaced soft palate.

Displaced Soft Palate

In a horse with a displaced soft palate, the epiglottis, which normally lies on top of the soft palate, becomes displaced below the palate. When this happens as the horse is exercising, it creates a partial obstruction as the horse breathes out and causes the palate to billow upward in front of the tracheal opening. The sound we hear is produced by the soft palate vibrating when the horse exhales. While tongue ties and specialized tack can help with clinical signs, surgical intervention might be needed and can return the athlete to full function, says Gray.

Laryngeal Hemiplegia

Other horses, such as racing Thoroughbreds or Warmblood sport horses, are more commonly diagnosed with laryngeal hemiplegia, she says. Horses with laryngeal hemiplegia have delayed abduction of or a paralyzed arytenoid.

The arytenoids are structures made of cartilage that form part of the larynx. Along with the epiglottis, the arytenoids help close the airway to food and water. The left and right arytenoid come together like sliding doors. The epiglottis then covers the arytenoids.

“In exercising horses, the arytenoids open to allow maximal airflow through the trachea,” says Gray. “If one side doesn’t open fully, the horse doesn’t get as much oxygen and tires more rapidly. In addition, the vocal cord that sits below the affected arytenoid vibrates and produces the roaring noise often associated with this condition.”

There are a variety of surgical options to treat laryngeal hemiplegia, depending on the degree of paralysis, the age of the horse, and the job of the horse.

Infections Cause Respiratory Distress

Horses that come in with respiratory distress, which is far less common, aren’t able to draw enough air into their airway, which typically is what causes the sounds they make. The veterinarian’s focus in this group of patients is relieving the stress of the patient by establishing adequate airflow. This might require placing an emergency tube into the trachea, which allows air to bypass the upper airway and permits the horse to breathe comfortably. The two most common reasons horses develop respiratory distress are related to infection.

Strangles, an infection caused by the bacterium Streptococcus equi, can result in an abscess in the lymph nodes of the neck. As the abscess gets larger, it puts pressure on and compresses the horse’s airway.

Another potential infection is known as arytenoid chondritis. In these cases the cartilage becomes infected and swells, so the arytenoids cannot open, which results in a narrowed airway and reduces the amount of air reaching the lungs with each breath. With both these conditions, bypassing the airway allows time to treat the infection and for the horse to potentially regain normal airway function.

Seek Help for Abnormal Respiratory Sounds

Unfortunately, says Gray, owners cannot prevent their horses from developing these conditions. “Since it is often an anatomic problem, there is no way to prevent it,” she explains. “However, we have many treatments available for upper airway conditions.”

The best thing owners can do, says Gray, is be vigilant and have the horse evaluated if he or she is making any airway noise, because early treatment is generally more successful. Your veterinarian can help guide you toward the right course of treatment and advise if surgery is needed for your horse.

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