A case-control study of respiratory disease in Thoroughbred racehorses in Sydney, Australia.
Abstract: In order to investigate the role of infectious agents in the aetiology of lower respiratory tract disease in Thoroughbred racehorses, a matched case-control study was conducted. Cases were identified by the presence of coughing, and were compared to a control population matched on time of sample collection and location within the same training establishment. Tracheal wash samples were collected from 100 cases and 148 controls. Case horses were more likely than controls to have endoscopic and cytological evidence of airway inflammation. There was no significant association between serological evidence of infection by commonly implicated respiratory viruses and coughing. Similarly, mycoplasma were rarely isolated and were not associated with disease. In contrast, there was a strong association between isolation of greater than a total of 10(3) colony-forming units/ml of tracheal wash and coughing. Individual bacterial species associated with disease included Streptococcus zooepidemicus, Streptococcus pneumoniae, Streptococcus suis, Streptococcus sanguis, Pasteurella spp and Bordetella bronchiseptica. This study provides evidence of the role of bacterial infection in the aetiology of lower respiratory tract inflammation in racehorses. However, in 58% of cases, few or no bacteria were isolated. Hence, at the time of identification of disease, there was no evidence of viral, bacterial or mycoplasmal infection in the majority of coughing horses. The aetiology of the signs observed in these horses requires further investigation.
Publication Date: 2001-05-16 PubMed ID: 11352347DOI: 10.2746/042516401776249796Google Scholar: Lookup
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- Journal Article
Summary
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The research article presents a case-control study examining the role of infectious agents in causing lower respiratory tract disease in Thoroughbred racehorses in Sydney, Australia. It reveals evidence of the role of bacterial infection in such diseases but calls for further investigation as a high number of cases showed no evidence of infection.
Introduction to the Research and the Methodology
- The researchers conducted a matched case-control study to explore the involvement of infectious agents in the cause of lower respiratory tract disease in Thoroughbred racehorses.
- The ‘cases’ were identified by the occurrence of coughing, and these were compared to a control population, which was matched based on the timing of sample collection and location within the same training establishment.
- Tracheal wash samples, a method used to evaluate lower airway diseases, were collected from 100 cases and 148 control horses.
Findings and Associations
- The horses identified as cases were found to be more likely than controls to show endoscopic and cytological evidence of airway inflammation, a clear sign of lower respiratory tract disease.
- The researchers found no significant association between serological evidence of infection by commonly implicated respiratory viruses and coughing, which suggests these viruses may not play a significant role in these diseases among Thoroughbred racehorses.
- Mycoplasma, another type of bacteria often associated with respiratory diseases, were rarely isolated and were also not associated with the said disease.
- On the contrary, there was a strong association between isolation of more than 103 colony-forming units/ml of bacteria in the tracheal wash and coughing, indicating a bacterial infection. The bacterial species found associated with the disease included Streptococcus zooepidemicus, Streptococcus pneumoniae, Streptococcus suis, Streptococcus sanguis, Pasteurella spp, and Bordetella bronchiseptica.
Conclusion and Suggestions for Future Research
- The study provides substantial evidence of the role played by bacterial infection in the cause of lower respiratory tract inflammation in racehorses.
- However, in 58% of cases, few or no bacteria were isolated. As a result, during the time when the disease was identified, there was no evidence of viral, bacterial, or mycoplasmal infection in most coughing horses.
- This suggests that the exact cause of signs observed in these horses remains undetermined, leading to the researchers’ call for further investigation into the aetiology of these disease symptoms.
Cite This Article
APA
Christley RM, Hodgson DR, Rose RJ, Wood JL, Reids SW, Whitear KG, Hodgson JL.
(2001).
A case-control study of respiratory disease in Thoroughbred racehorses in Sydney, Australia.
Equine Vet J, 33(3), 256-264.
https://doi.org/10.2746/042516401776249796 Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, University of Sydney, Australia.
MeSH Terms
- Animals
- Australia
- Bordetella / isolation & purification
- Bordetella Infections / microbiology
- Bordetella Infections / veterinary
- Bronchoscopy / veterinary
- Case-Control Studies
- Colony Count, Microbial
- Cough
- Horse Diseases / etiology
- Horse Diseases / microbiology
- Horses
- Inflammation
- Mycoplasma / isolation & purification
- Pasteurella / isolation & purification
- Pasteurella Infections / microbiology
- Pasteurella Infections / veterinary
- Respiratory Tract Infections / etiology
- Respiratory Tract Infections / microbiology
- Respiratory Tract Infections / veterinary
- Streptococcal Infections / microbiology
- Streptococcal Infections / veterinary
- Streptococcus / isolation & purification
- Trachea / cytology
- Trachea / microbiology
Citations
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- Stucchi L, Alberti E, Stancari G, Conturba B, Zucca E, Ferrucci F. The Relationship between Lung Inflammation and Aerobic Threshold in Standardbred Racehorses with Mild-Moderate Equine Asthma.. Animals (Basel) 2020 Jul 27;10(8).
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