Researchers Describe New Equine Respiratory Condition

The bacterium Stenotrophomonas maltophilia can be associated with chronic lower airway disease in horses, reports a group of Danish researchers.

S. maltophilia is a Gram-negative bacterium that is causing disease more often in humans, particularly among the immunocompromised population, but it is only rarely reported as causing infection in animals.

The research team led by Lotte Winther, a PhD student in the Department of Large Animal Sciences, Faculty of Life Sciences at the University of Copenhagen, noted "S. maltophilia has only once been reported as an equine pathogen."

In 2007 Winther and colleagues collected data from seven horses with respiratory infections from which S. maltophilia was cultured. In all cases chronic coughing and an exudate composed of both mucus and pus was noted in the lower trachea during endoscopic examinations. DNA testing indicated that all seven horses were infected with the same or very similar types of the bacterium, and S. maltophilia cultured from the tracheas of affected horses were resistant to a wide variety of antibiotics, including:

  • All penicillins and cephalosporins;
  • Imipenem;
  • Gentamicin;
  • Amikacin; and
  • Rifampin.

Together, the data suggest that S. maltophilia can act as a respiratory pathogen and should be considered in horses with a history of respiratory signs and with abundant mucopurulent material in the trachea.

The authors emphasized that commonly administered antibiotics for equine respiratory infections are not active against S. maltophilia.

"Prolonged administration of tetracyclines (greater than 10 to 14 days) is an effective treatment, especially for adult horses," advised the researchers.

Additional details regarding the disease are described in the study, "Association of Stenotrophomonas maltophilia infection with lower airway disease in the horse: A retrospective case series," which is scheduled to be published in an upcoming edition of The Veterinary Journal. The abstract is available on PubMed.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.