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Bacterial infection of the lower respiratory tract in 34 horses.
Abstract: To investigate associations between the bacteriology and aspects of history, clinical presentation, outcome and pathology of lower respiratory tract disease of 34 horses. Methods: Detailed aerobic and anaerobic bacteriological investigations were performed on clinical specimens from horses with pneumonia, lung abscessation and necrotic pneumonia with or without pleurisy in an attempt to identify those bacteria that might contribute to the initiation and progression of infection. Results: Bacteria were cultured from 33 of the 34 horses. In ten cases, only aerobic/facultatively anaerobic isolates were cultured while aerobic/facultatively anaerobic bacteria and obligately anaerobic bacteria were isolated in the other 23 cases. Moderate to large numbers of anaerobic bacteria were isolated only when the estimated duration of illness was at least five days. Bacteria were not cultured from 12 of the pleural fluid samples but were always cultured from pulmonary samples (either transtracheal aspirates from live horses or pulmonary lesions at necropsy). Streptococcus equi subsp zooepidemicus was isolated in the three cases where only one bacterial species was cultured. In the other 30 cases, multiple species were isolated. These included most often and in greatest numbers, Streptococcus equi subsp zooepidemicus, Pasteurellaceae, Escherichia coli, anaerobic cocci, Eubacterium fossor, Bacteroides tectum, Prevotella heparinolytica, Fusobacterium spp, and pigmented members of the genera Prevotella and Porphyromonas. Aerobic/facultatively anaerobic organisms were isolated from 97% of horses, while obligately anaerobic organisms were cultured from 68% of horses. Conclusions: There was no association between the isolation of any specific bacterium and the outcome of disease. However, obligately anaerobic bacteria (such as anaerobic cocci, Bacteroides tectum, P heparinolytica and Fusobacterium spp) and the facultatively anaerobic species Escherichia coli, were recovered more commonly from horses that died or were euthanased than from those that survived. There was an association between failure of horses to recover from pleuropneumonia and delay in diagnosis and initiation of treatment.
Publication Date: 2000-09-09 PubMed ID: 10979512DOI: 10.1111/j.1751-0813.2000.tb11901.xGoogle Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates the associations between various bacterial species and aspects of lung infections in horses such as medical history, clinical presentation, progression, and outcome.
Research Methodology
- The study executed comprehensive aerobic (oxygen-required for growth) and anaerobic (can grow without oxygen) bacteriological tests on clinical specimens collected from horses suffering from pneumonia, lung abscessation, and necrotic pneumonia with or without pleurisy.
- The aim was to identify bacterial species contributing to the onset and advancement of infections.
Research Findings
- Bacteria was found in 33 of the 34 horses. Ten horses had only aerobic/facultatively anaerobic bacteria while the rest had both aerobic/facultatively anaerobic and obligately anaerobic bacteria.
- Significant numbers of anaerobic bacteria were only found in horses with an estimated illness duration of at least five days.
- While bacteria could not be cultured from 12 of the pleural fluid samples, they were consistently found in lung samples.
- Instances were found in which only one bacterial species – Streptococcus equi subsp zooepidemicus – was isolated. In the other cases, multiple species were isolated, most often being Streptococcus equi subsp zooepidemicus, Pasteurellaceae, Escherichia coli, anaerobic cocci, Eubacterium fossor, Bacteroides tectum, Prevotella heparinolytica, Fusobacterium spp, and pigmented Prevotella and Porphyromonas.
- Nearly all horses, or 97%, had aerobic/facultatively anaerobic organisms, while 68% also had obligately anaerobic organisms.
Conclusions and Insights
- The study found no direct correlation between the presence of a specific bacterium and the disease outcome. However, obligately anaerobic bacteria (such as anaerobic cocci, Bacteroides tectum, P heparinolytica and Fusobacterium spp) and the facultatively anaerobic species Escherichia coli, were found more often in horses that either died or were euthanized, as opposed to those that survived.
- A noticeable association was found between horses failing to recover from pleuropneumonia (lung and pleural infection) and a delay in diagnosis and treatment initiation. This could imply the importance of early detection and intervention for a favorable outcome.
Cite This Article
APA
Racklyeft DJ, Love DN.
(2000).
Bacterial infection of the lower respiratory tract in 34 horses.
Aust Vet J, 78(8), 549-559.
https://doi.org/10.1111/j.1751-0813.2000.tb11901.x Publication
Researcher Affiliations
- Satur Veterinary Clinic, Scone, New South Wales.
MeSH Terms
- Animals
- Bacteria, Anaerobic / drug effects
- Bacteria, Anaerobic / isolation & purification
- Female
- Horse Diseases / drug therapy
- Horse Diseases / microbiology
- Horse Diseases / pathology
- Horses
- Male
- Microbial Sensitivity Tests
- New South Wales
- Pneumonia, Bacterial / drug therapy
- Pneumonia, Bacterial / microbiology
- Pneumonia, Bacterial / pathology
- Pneumonia, Bacterial / veterinary
- Severity of Illness Index
- Treatment Outcome
Citations
This article has been cited 15 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.
- Mondo E, Rinnovati R, Spadari A, Giacometti F, Serraino A, Savini F, Piva S. First isolation of Klebsiella variicola from a horse pleural effusion. BMC Vet Res 2021 Feb 12;17(1):75.
- Hilbert M, Csadek I, Auer U, Hilbert F. Antimicrobial Resistance-Transducing Bacteriophages Isolated from Surfaces of Equine Surgery Clinics - A Pilot Study. Eur J Microbiol Immunol (Bp) 2017 Dec 18;7(4):296-302.
- Arroyo MG, Slovis NM, Moore GE, Taylor SD. Factors Associated with Survival in 97 Horses with Septic Pleuropneumonia. J Vet Intern Med 2017 May;31(3):894-900.
- Estell KE, Young A, Kozikowski T, Swain EA, Byrne BA, Reilly CM, Kass PH, Aleman M. Pneumonia Caused by Klebsiella spp. in 46 Horses. J Vet Intern Med 2016 Jan-Feb;30(1):314-21.
- Tomlinson JE, Reef VB, Boston RC, Johnson AL. The Association of Fibrinous Pleural Effusion with Survival and Complications in Horses with Pleuropneumonia (2002-2012): 74 Cases. J Vet Intern Med 2015 Sep-Oct;29(5):1410-7.
- Kinoshita Y, Niwa H, Katayama Y, Hariu K. Dominant obligate anaerobes revealed in lower respiratory tract infection in horses by 16S rRNA gene sequencing. J Vet Med Sci 2014 Apr;76(4):587-91.
- Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
- Albert E, Biksi I, Laczkó L, Miló L, Cseri K, Bőkényné Tóth R, Papp D, Halmay D, Bódai E, Bakos Z. Streptococcus hillyeri isolated from septic pleuritis in a horse. J Vet Diagn Invest 2025 Mar;37(2):393-397.
- Hepworth-Warren KL, Love K. Survey of the approach to the diagnosis and management of bacterial pneumonia in adult horses by equine veterinarians. Front Vet Sci 2024;11:1484970.
- 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.
- Sun J, Xu X, Gao S, Pan Q, Liu Z, Huang Y, Lian Y. Refractory pneumonia caused by Prevotella heparinolytica: a case report. J Med Case Rep 2024 Apr 30;18(1):213.
- Kuroda T, Minamijima Y, Niwa H, Mita H, Tamura N, Fukuda K, Toutain PL, Ohta M. Pharmacokinetics/pharmacodynamics cut-off determination for fosfomycin using Monte Carlo simulation in healthy horses. J Vet Med Sci 2024 Apr 10;86(4):413-420.
- Labens R, Raidal S, Borgen-Nielsen C, Pyecroft S, Pant SD, De Ridder T. Wound healing of experimental equine skin wounds and concurrent microbiota in wound dressings following topical propylene glycol gel treatment. Front Vet Sci 2023;10:1294021.
- Cantelmi MC, Merola C, Averaimo D, Chiaverini A, Cito F, Cocco A, Di Teodoro G, De Angelis ME, Di Bernardo D, Auzino D, Petrini A. Identification of the Novel Streptococcus equi subsp. zooepidemicus Sequence Type 525 in Donkeys of Abruzzo Region, Italy. Pathogens 2023 May 23;12(6).
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