Acute leptospirosis in horses: A retrospective study of 11 cases

We often find leptospirosis as a suspect for cases of abortion and ocular disease but do not usually discuss the acute onset of a systemic lepto infection. This study helps fill this void. Of note is that any horse with signs of systemic inflammation and renal (kidney) injury should be suspected of lepto infection.
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Acute leptospirosis in horses: A retrospective study of 11 cases (2015-2023)

J Vet Intern Med. 2024 Aug 28. doi: 10.1111/jvim.17184. Online ahead of print.
Authors
Lynette Ramsay 1 2 , Christina Eberhardt 2 3 , Angelika Schoster 2 4
Affiliations

1 Ramsay Equine Medical, Odense, Denmark.
2 Vetsuisse Faculty, Clinic for Equine Internal Medicine, University of Zurich, Zurich, Switzerland.
3 Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa.
4 Faculty of Veterinary Medicine, Equine Clinic, Center for Clinical Veterinary Medicine, LMU Munich, Germany.

PMID: 39194176
DOI: 10.1111/jvim.17184

Abstract

Background: Reports of leptospirosis in horses are limited.

Objectives: To describe the clinical and diagnostic findings of acute systemic leptospirosis in horses.

Animals: Eleven client-owned horses presented to an equine hospital because of acute onset of disease between 2015 and 2023.

Methods: Retrospective case series. Horses diagnosed with leptospirosis by 1 or more of urine PCR, serologic microscopic agglutination test (MAT), and histopathology.

Results: Common clinical signs included lethargy (10), anorexia (10), fever (9), tachypnea (9), abnormal lung sounds (9), and epistaxis (6). Acute kidney injury was present in all cases. Evidence of pulmonary hemorrhage and liver disease was found in 8 (73%) and 6 (55%) horses, respectively. In 6 (55%) horses, kidneys, lungs, and liver were affected. Urine quantitative polymerase chain reaction for detection of pathogenic Leptospira spp. was positive in 6 (55%) cases. On serology Leptospira interrogans serovar Australis, Autumnalis, and Bratislava accounted for 86% of all titers ≥1 : 800. Overall case fatality rate was 4/11 (36%). Main findings on necropsy were tubular necrosis, interstitial nephritis, hemorrhage in the alveoli, pulmonary edema, periportal hepatitis and necrosis, cholestasis, and cholangitis.

Conclusions and clinical importance: Leptospirosis should be considered as a differential diagnosis in horses with evidence of acute systemic inflammation and acute renal injury, epistaxis, or hepatic disease. For increased likelihood of identifying positive cases, both MAT serology and urine PCR should be performed.

Keywords: Leptospira; hepatic involvement; lung bleeding; systemic disease.

© 2024 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.