Cornell Develops Model to Study Leptospira interrogans in Horses

Cornell University researchers have successfully created a model in horses to study infections caused by the bacterium Leptospira interrogans.

In horses, leptospirosis can cause fever, icterus (jaundice), uveitis and recurrent uveitis, abortion, and kidney failure, though clinical signs are variable.

"The exact prevalence of leptospiral infections in horses is unknown, and the course of disease in terms of timing of serologic response, spread of the bacterium in the blood, excretion in urine, and ocular infections remains unclear," said Yung-Fu Chang, DVM, MS, PhD, Dipl. ACVM (veterinary microbiology), Director of the Infectious Disease research laboratory and a professor in Cornell's department of population medicine.

The purpose of this study was to determine responses (both serological and hematological) in horses exposed to L. interrogans serovar Kennewicki--the most common cause of Leptospira infections in horses in North America.

Chang and colleagues used L. interrogans serovar Kennewicki isolated from the liver of an aborted foal for this study. Four horses negative for leptospirosis were inoculated with the bacterium. Two horses were inoculated with 5x108 organisms subcutaneously and by topical application to the surface of the left eye, while the other two horses were inoculated with 1x108 organisms in the abdominal cavity and to the surface of the left eye.

Horses were monitored for 60 days.

Key findings of the study were: 

  • Fevers reaching 39.3-40°C occur as early as one day post-inoculation;
  • The bacterium was found in the blood and urine but not in the eyes (aqueous humor) of exposed horses; and,
  • Antibodies against L. interrogansdeveloped in all inoculated horses.

"This study demonstrated that our equine leptospirosis model was successful, which will further our understanding of the course of disease in horses infected with leptospirosis," concluded Chang.

The study, "Experimental Leptospira interrogans serovar Kennewicki infection of horses," is scheduled to be published in an upcoming edition of the Journal of Veterinary Internal Medicine.

The abstract is available on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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