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Medical Index
First Posted Mar 25, 2008
Jul 30, 2010

Roarer or Whistler

Marion duPont Scott Equine Medical Center offers Treatments for Upper Respiratory Disease
by Marjorie Musick - Posted with permission.

(The following is a direct quote of that article) I have bolded the paragraph directly dealing with roarers.

LEESBURG, Va., March 7, 2008 -- At Virginia Tech's Marion duPont Scott Equine Medical Center, a variety of treatments are available for correcting disorders of the upper respiratory system and improving the odds of performance success.

Equine upper respiratory disorders often have symptoms such as labored breathing, flared nostrils, and strange noises during exercise. These conditions can be detrimental to an equine athlete's health and can also inhibit performance during competition

"Respiratory disease is probably second only to lameness in terms of performance limiting illnesses in horses," said Dr. Harold McKenzie, assistant professor of equine medicine. "The function of the respiratory tract is gas exchange - getting the oxygen in, getting the carbon dioxide out - so anything that limits the flow of air is likely to impair athletic ability."

Although all horses can suffer from diseases affecting the nasal passage, larynx, soft palate, pharynx, and sinuses that comprise a horse's upper airway system, these conditions predominantly affect athletes competing in racing, dressage, hunting, jumping, polo, driving, and other disciplines.

"Performance horses go out and train at high-speeds and breathe at a faster rate to keep up with oxygen debt," said Dr. Nat White, the Jean Ellen Shehan Professor and director of the center. "Any problems with air flow due to soft tissue damage or control of the upper airway movement can cause increased noise during breathing and a lack of oxygen reaching the lungs."

The most common upper airway complication that Dr. Ken Sullins, professor of equine surgery, has seen in his patients is laryngeal hemiplegia, also known as "roaring," which is acquired as a result of trauma to the left recurrent laryngeal nerve. Other illnesses that frequently reduce air flow include dorsal displacement of the soft palate, pharyngeal collapse, airway obstruction, pharyngeal lymphoid hyperplasia, entrapped epiglottis, and arytenoid chondritis.

"The causes vary from inflammatory conditions to degeneration of nerves that control upper airway function," said Sullins. "The upper airway is very sensitive to irritation and significant issues stem from airway turbulence during exercise when the throat is inflamed."

According to Sullins, when a patient at the Marion duPont Scott Equine Medical Center is presented with an upper respiratory problem, the diagnosis is usually based on an analysis of the animal's health history, a physical exam, monitoring during exercise on a high-speed treadmill, and imaging of the upper airway system by ultrasound and standing video endoscopy. Other imaging technologies, including nuclear scintigraphy, ultrasound and digital radiography, may be also be used if further visuals are required.

"If the cause cannot be identified during the endoscopy, then we put the horse on a treadmill and monitor them while they run," said Sullins.

Although medical therapy is available for some of these maladies, surgical intervention is often required.

"Fundamentally, most, if not all, upper respiratory problems are mechanical in nature and therefore tend to be treated through structural repairs," said McKenzie. "So if something is obstructing the flow of air, you can suture it back or remove it and the problem goes away."

Further research is needed in order to pinpoint the specific causes of many upper airway complications in performance horses. However, the specialists who study the diseases have their own theories.

"There seems to be a geographical component for some laryngeal infections," said Sullins."We suspect that it might have something to do with racetrack surfaces or air quality in specific areas. Certainly horses that race on turf have reduced incidence of this type of problem."

Information regarding the Marion duPont Scott Equine Medical Center's clinicians and services is available online. Consultations may be scheduled by calling (703) 771-6800.

Virginia Tech's Marion duPont Scott Equine Medical Center is a premier full-service equine hospital located in Leesburg, Va., that offers advanced specialty care, 24-hour emergency treatment and diagnostic services for all ages and breeds of horses. One of three campuses that comprise the Virginia-Maryland Regional College of Veterinary Medicine, the center and its team of equine specialists are committed to providing exceptional treatment to patients, superior service to clients and cutting-edge research to the equine industry.

Contact Marjorie Musick at mzmusick @vt.edu or (703) 771-6800.

The following is more information dealing with "whistlers" and "roarers."

Whistlers and Roarers

Both terms are used to describe the abnormal respiratory noise heard while a horse is exercising. When the horse breaths in a high pitched sound may be heard which is often described as a whistle. That noise can be much louder and actually sound like a roar.

Causes of the Noise

When your horse breaths, air is taken in through the nostrils. It passes through the nasal passages into the throat (pharynx). The pharynx is a muscular tube. From the pharynx the air passes through the larynx (voice box). It then enters the windpipe (trachea) and lungs. While your horse is exercising the nostrils dilate and the horse extends its head and neck. By doing this the horse is able to take in more air because the pharynx and larynx open further. If there is any obstruction of the increased air flow, you may hear your horse make a whistling or roaring sound.

Laryngeal hemiplegia (one-sided paralysis) is the most common cause of horses making abnormal noises while exercising. The noise is caused by partial or total paralysis of one (usually the left) side of the larynx. Larger horses tend to be more apt to have this problem. The nerve that is injured is called the long nerve or recurrent laryngeal nerve. However, any horse or pony can have this problem. The problem is progressive. Often the paralyzed side will collapse inwards.

Confirmation of Laryngeal Hemiplegia
  • Audible noise during exercise
  • Endoscopic examination
  • Clean barn
  • No dust, no mold, good ventilation
  • Try to avoid allergic reactions
  • Regular vaccinations
  • Avoid upper respiratory infections
  • Hobday operation - "Problems with getting air to the horse's lungs can be caused by damage or malfunctioning tissue obstructing the airways at some point. There are various operations that can be done to stiffen up the muscles, connective tissue etc. in the Pharynx or Larynx to ensure they are held open fully (if not correctly). For instance if an area of paralysis means the muscular flap is not retracting correctly it can be 'fired' to stiffen it so that it does. This can be done in either area. The hobday operation involves surgically removing a piece of tissue (often paralyzed) which makes more room and, again, causes scar tissue to form. This is done in more severe cases."
    British Racing Glossary
  • Tie back operation - "Problems with getting air to the horse's lungs can be caused by damage or malfunctioning tissue obstructing the airways at some point. There are various operations that can be done to stiffen up the muscles, connective tissue etc. in the Pharynx or Larynx to ensure they are held open fully (if not correctly). For instance if an area of paralysis means the muscular flap is not retracting correctly it can be 'fired' to stiffen it so that it does. This can be done in either area. In more severe cases stitches may be used to hold open the airway and this is termed a tie-back operation and is often done along with a hobday procedure." British Racing Glossary
  • Tracheotomy - Not usually done. "In the most severe cases a tracheotomy is done where a plastic or brass tube is put directly into the windpipe and out through a valve on the underside of the neck (i.e., bypassing any of the compromised nose-pharynx-larynx route). A bung will normally be placed into the tube in everyday conditions but removed when the horses is exerting itself to allow clearer breathing." British Racing Glossary
Other Causes of Whistling and Roaring
  • Lymphoid hyperplasia - The rapid growth of normal cells that resemble lymph tissue. Tissue lining the pharynx becomes inflamed and nodules form.
  • Cysts - Fluid-filled sacs may form beneath the epiglottis. The epiglottis is a triangular cartilage at the base of the larynx. Its job is to prevent food material from going down "the wrong way" If a cyst forms under it, the epiglottis is pushed up and it obstructs the opening of the larynx causing a noise. Large cysts require surgical treatment to remove them.
  • Infections, tumors or other growths or obstructions in the nostrils or nasal passages may result in the horse making an abnormal noise.
  • Epiglottic entrapment - A condition where the epiglottis is trapped under an abnormal fold of tissue and cannot move normally. Treatment consists of cutting the abnormal tissue, for which a surgical procedure is required.
  • Congenital problems - Conditions of the pharynx and larynx which are present from birth. In general terms, these conditions cannot be treated.

  • Roaring

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