Equine Respiratory Disease Diagnosis Aided by Fluid Evaluation

Respiratory disease in horses can be accurately assessed through laboratory evaluation of respiratory fluids, according to a new review by French and Belgian researchers.

When combined with clinical examinations, bronchoalveolar lavage (BAL) and tracheal washes reveal important information leading to the diagnosis and proper treatment of respiratory conditions which result in poor performance in horses, the review states. Poor performance is described as deficiencies in athletic efforts in a horse which previously was performing well, or performance that is not as high as reasonably expected for a particular horse.

"Airway disease should be considered in every horse not performing at its expected level," said Eric Richard, DVM, MSc, researcher at the Frank Duncombe Laboratory in France and at the Department of Physiology of the Faculty of Veterinary Medicine at the University of Liège in Belgium. "In human athletes, it's the heart that usually is the primary physiological system to hinder performance. But in horses, the respiratory system is the first limiting factor, even in healthy subjects."

Although lower airway evaluation has been studied in horses over the past 30 years, Richard said his team provides the most recent review of the cytological reference values found in various studies worldwide.

"The aim of this review is to present currently published scientific knowledge that will help clinicians objectively interpret laboratory evaluations of respiratory fluids, so as to accurately assess causes of poor performance," Richard said. "However, no general conclusions can be made to apply to every horse. The background of the horse and knowledge of the veterinarian will ultimately determine the diagnosis, treatment, and prognosis for each poorly performing horse."

Tracheal washes and BALs can be performed during a 10 to 15-minute procedure at the stable with the use of a nose twitch and, for BALs, sedation, according to Richard. In tracheal washes, a veterinarian passes an endoscope through a nostril into the trachea, where a small amount of saline is injected and then re-aspirated. With a BAL, a gastroscope or BAL tube is passed down the trachea until it is wedged into a distal bronchus, and saline is sequentially infused and aspirated.

The researchers emphasized that exercise might affect the results and that respiratory fluids should always be drawn at the same interval between sessions of exercise in order to have comparable results. Horses can be ridden lightly the day after the procedures.

The study, "Laboratory findings in respiratory fluids of the poorly-performing horse," was published in the May 2009 edition of Veterinary Journal. The abstract is available on PubMed.  

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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