Retrospective study of fatal pneumonia in racehorses.
Abstract: Respiratory diseases have a major impact on racehorses in training and are often cited as the second most common reason of horses failing to perform. Cases were submitted by the California Horse Racing Board to the California Animal Health and Food Safety laboratory for postmortem examination between January 1, 2005 and December 31, 2014. We determined the demographics of racehorses with fatal pneumonia, characterized the pathologic findings in animals with a postmortem diagnosis of respiratory infection, and determined the most significant pathogens associated with lower respiratory tract disease. We analyzed autopsy reports from 83 horses with a diagnosis of pneumonia, bronchopneumonia, and/or pleuropneumonia. The most common presentation was pleuropneumonia (71% of cases), with extensive areas of lytic necrosis and abscesses of the pulmonary parenchyma. Streptococcus equi ssp. zooepidemicus, a normal mucosal commensal of the upper respiratory tract of healthy horses, was the most commonly isolated organism (72% of cases), either in pure culture or accompanied by other aerobic or anaerobic bacteria. Its presence in the pulmonary parenchyma is associated with severe and extensive damage to the lung. Furthermore, this agent has zoonotic potential, which stresses the importance of early detection and proper management of cases of pneumonia in racehorses.
Publication Date: 2017-07-07 PubMed ID: 28681687DOI: 10.1177/1040638717717290Google Scholar: Lookup
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- Journal Article
Summary
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The research examines the significant impact of respiratory infections on racehorses, identifying the main pathogens, their effects, and the necessity for immediate attention towards pneumonia in these animals.
Study Background and Methodology
- The researchers conducted a retrospective study focusing on racehorses affected by fatal pneumonia cases between January 1, 2005, and December 31, 2014.
- These cases were submitted to the California Animal Health and Food Safety laboratory by the California Horse Racing Board for postmortem examination.
Demographics and Pathologic Findings
- The study aimed to determine the racehorses’ demographics with fatal pneumonia and categorize postmortem pathological findings in animals diagnosed with respiratory infections.
- Through autopsy reports, the researchers managed to analyze 83 cases with diagnoses related to pneumonia, bronchopneumonia, or pleuropneumonia.
- Pleuropneumonia was the most prevalent form, accounting for 71% of cases, characterized by extensive lytic necrosis areas and pulmonary parenchyma abscesses.
Pathogens identified and Impacted Areas
- The research investigated the most critical pathogens related to lower respiratory tract diseases in these animals.
- Streptococcus equi ssp. zooepidemicus, a standard mucosal commensal in healthy horses’ upper respiratory tract, was identified as the most frequently isolated organism (found in 72% of cases).
- This pathogen was either present in pure culture or alongside other aerobic or anaerobic bacteria. Its occurrence in the pulmonary parenchyma resulted in severe and extensive lung damage.
Importance of Early Detection and Proper Management
- The study underscores the urgent need for the early detection and correct management of pneumonia cases in racehorses.
- Special emphasis is given to the zoonotic potential of the identified agent (Streptococcus equi ssp. zooepidemicus), highlighting the risk it poses not only to animal health but also human health.
Cite This Article
APA
Carvallo FR, Uzal FA, Diab SS, Hill AE, Arthur RM.
(2017).
Retrospective study of fatal pneumonia in racehorses.
J Vet Diagn Invest, 29(4), 450-456.
https://doi.org/10.1177/1040638717717290 Publication
Researcher Affiliations
- California Animal Health and Food Safety Laboratory System, San Bernardino Branch (Carvallo, Uzal), CA.
- Davis Branch (Diab, Hill), CA.
- School of Veterinary Medicine, University of California-Davis, Davis, CA (Arthur).
- California Animal Health and Food Safety Laboratory System, San Bernardino Branch (Carvallo, Uzal), CA.
- Davis Branch (Diab, Hill), CA.
- School of Veterinary Medicine, University of California-Davis, Davis, CA (Arthur).
- California Animal Health and Food Safety Laboratory System, San Bernardino Branch (Carvallo, Uzal), CA.
- Davis Branch (Diab, Hill), CA.
- School of Veterinary Medicine, University of California-Davis, Davis, CA (Arthur).
- California Animal Health and Food Safety Laboratory System, San Bernardino Branch (Carvallo, Uzal), CA.
- Davis Branch (Diab, Hill), CA.
- School of Veterinary Medicine, University of California-Davis, Davis, CA (Arthur).
- California Animal Health and Food Safety Laboratory System, San Bernardino Branch (Carvallo, Uzal), CA.
- Davis Branch (Diab, Hill), CA.
- School of Veterinary Medicine, University of California-Davis, Davis, CA (Arthur).
MeSH Terms
- Animals
- Bacteria / classification
- Bacteria / isolation & purification
- Bronchopneumonia / epidemiology
- Bronchopneumonia / microbiology
- Bronchopneumonia / mortality
- Bronchopneumonia / veterinary
- California / epidemiology
- Horse Diseases / diagnosis
- Horse Diseases / epidemiology
- Horse Diseases / mortality
- Horses
- Pleuropneumonia / epidemiology
- Pleuropneumonia / microbiology
- Pleuropneumonia / mortality
- Pleuropneumonia / veterinary
- Pneumonia, Bacterial / epidemiology
- Pneumonia, Bacterial / microbiology
- Pneumonia, Bacterial / mortality
- Pneumonia, Bacterial / veterinary
- Retrospective Studies
Citations
This article has been cited 7 times.- Rahman A, Uzal FA, Hassebroek AM, Carvallo FR. Retrospective study of pneumonia in non-racing horses in California. J Vet Diagn Invest 2022 Jul;34(4):587-593.
- Gergeleit H, Verspohl J, Rohde J, Rohn K, Ohnesorge B, Bienert-Zeit A. A prospective study on the microbiological examination of secretions from the paranasal sinuses in horses in health and disease. Acta Vet Scand 2018 Jul 5;60(1):43.
- Corpa JM, Carvallo F, Anderson ML, Nyaoke AC, Moore JD, Uzal FA. Streptococcus equi subspecies zooepidemicus septicemia in alpacas: three cases and review of the literature. J Vet Diagn Invest 2018 Jul;30(4):598-602.
- Junkkari R, Mykkänen A, Sulku P, Rantala M, Pohjanvirta T, Eklund M, Pelkonen S, Grönthal T. Occurrence, antibiotic susceptibility and genetic variation of Streptococcus zooepidemicus in Finnish weanling horses with and without respiratory infection. Acta Vet Scand 2026 Jan 27;68(1):7.
- Pınar O, Çelik Doğan C, Aktaran Bala D, Kumaş C, Mete A. Analysis of the presence of Beta-hemolytic streptococci and cytological profiles in horse tracheal lavage samples with diverse clinical respiratory symptoms. BMC Vet Res 2025 Oct 2;21(1):558.
- Hallowell KL, Hepworth-Warren KL, Dembek K. An updated description of bacterial pneumonia in adult horses and factors associated with death. J Vet Intern Med 2024 Sep-Oct;38(5):2766-2775.
- Witkowska-Piłaszewicz O, Malin K, Dąbrowska I, Grzędzicka J, Ostaszewski P, Carter C. Immunology of Physical Exercise: Is Equus caballus an Appropriate Animal Model for Human Athletes?. Int J Mol Sci 2024 May 10;25(10).
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