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Predictor variables for and complications associated with Streptococcus equi subsp equi infection in horses.
Abstract: To evaluate predictor variables for and complications associated with Streptococcus equi subsp equi infection (strangles) in horses. Methods: Retrospective case-control study. Methods: 108 horses with strangles (cases) and 215 horses without strangles (controls). Methods: Medical records from January 2005 through July 2012 were reviewed. Cases were defined as horses with clinical signs of strangles (pyrexia, retropharyngeal lymphadenopathy, and mucopurulent nasal discharge) that were associated with a confirmed strangles outbreak or had positive results for S equi on PCR assay or bacteriologic culture. Controls were defined as horses with pyrexia that did not meet the other criteria for cases. Data compared between cases and controls included signalment, clinical signs, diagnostic test results, and disease complications and outcome. Logistic regression was used to identify variables associated with strangles and its complications. Results: Clinical signs of strangles were not evident in 12 of 25 cases classified as S equi carriers (infected > 40 days). Predictor variables associated with strangles included mucopurulent nasal discharge and external abscesses in the pharyngeal region. Strangles was more likely to be diagnosed in the spring than in the summer. Cases with anemia were more likely to develop purpura hemorrhagica than were cases without anemia. No risk factors were identified for the development of guttural pouch empyema or metastatic abscesses. Conclusions: Results indicated that not all horses infected with S equi develop clinical signs of strangles. We recommend that guttural pouch endoscopy and lavage with PCR assay of lavage fluid samples be performed to identify S equi carrier horses.
Publication Date: 2015-11-01 PubMed ID: 26517620DOI: 10.2460/javma.247.10.1161Google 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
Summary
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The study investigates the predictor factors and complications linked to Streptococcus equi subsp equi infection, known as strangles, in horses. Through a retrospective case-control study, the research looks into variables associated with strangles, clinical symptoms, disease complications and outcomes.
Research Methodology
- The study involved a retrospective case-control research involving 108 horses with strangles and 215 horses without the infection as the control group.
- The research analyzed medical records from the period January 2005 to July 2012.
- The cases comprised horses displaying clinical indications of strangles, linked to a confirmed strangles outbreak or were detected positively for S equi through PCR assay or bacterial culture.
- The control group involved horses with pyrexia, but did not exhibit other case criteria.
- The collected data for cases and controls included signalment, clinical symptoms, diagnostic test findings, and disease complications and the resultant outcomes.
Study Results
- The study indicated that not all infected horses showed clinical signs of strangles.
- Some of the predictor variables linked to strangles include mucopurulent nasal discharge and exterior abscesses in the pharyngeal region.
- Strangles were more prevalent during spring than summer.
- Purpura hemorrhagica was more likely to develop in horses with anemia than those without.
- No risk factors associated with the development of guttural pouch empyema or metastatic abscesses were identified.
Conclusion and Recommendations
- The results of the research demonstrated that not all horses infected with S equi manifest clinical indications of strangles implying that identification of S equi infection cannot be solely determined by clinical signs.
- Based on these findings, the researchers recommend conducting guttural pouch endoscopy and lavage with PCR assay of lavage fluid samples for accurate identification of S equi carrier horses.
Cite This Article
APA
D￮ LR, Stefanovski D, Boston RC, Boyle AG.
(2015).
Predictor variables for and complications associated with Streptococcus equi subsp equi infection in horses.
J Am Vet Med Assoc, 247(10), 1161-1168.
https://doi.org/10.2460/javma.247.10.1161 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Anti-Bacterial Agents / therapeutic use
- Case-Control Studies
- Female
- Horse Diseases / drug therapy
- Horse Diseases / microbiology
- Horse Diseases / pathology
- Horses
- Male
- Nasopharynx / microbiology
- Retrospective Studies
- Streptococcal Infections / drug therapy
- Streptococcal Infections / microbiology
- Streptococcal Infections / pathology
- Streptococcal Infections / veterinary
- Streptococcus equi / classification
Citations
This article has been cited 9 times.- McLinden LA, Kemp-Symonds JG, Daly JM, Blanchard AM, Waller AS, Freeman SL. Effectiveness of a screening protocol employed at a UK rescue centre to prevent introduction of strangles. Equine Vet J 2026 Mar;58(2):466-475.
- McGlennon AA, Verheyen KL, Newton JR, van Tonder A, Wilson H, Parkhill J, de Brauwere N, Frosth S, Waller AS. Unwelcome neighbours: Tracking the transmission of Streptococcus equi in the United Kingdom horse population. Equine Vet J 2026 Mar;58(2):533-548.
- Kabir A, Lamichhane B, Habib T, Adams A, El-Sheikh Ali H, Slovis NM, Troedsson MHT, Helmy YA. Antimicrobial Resistance in Equines: A Growing Threat to Horse Health and Beyond-A Comprehensive Review. Antibiotics (Basel) 2024 Jul 29;13(8).
- Jaramillo-Morales C, James K, Barnum S, Vaala W, Chappell DE, Schneider C, Craig B, Bain F, Barnett DC, Gaughan E, Pusterla N. Voluntary Biosurveillance of Streptococcus equi Subsp. equi in Nasal Secretions of 9409 Equids with Upper Airway Infection in the USA. Vet Sci 2023 Jan 20;10(2).
- Martin KH, Redding LE, Boyle AG. Factors Influencing Veterinarian Opinion on Reporting of Equine Strangles in the United States. J Equine Vet Sci 2022 Jul;114:103947.
- Pringle J, Venner M, Tscheschlok L, Waller AS, Riihimäki M. Markers of long term silent carriers of Streptococcus equi ssp. equi in horses. J Vet Intern Med 2020 Nov;34(6):2751-2757.
- Pringle J, Storm E, Waller A, Riihimäki M. Influence of penicillin treatment of horses with strangles on seropositivity to Streptococcus equi ssp. equi-specific antibodies. J Vet Intern Med 2020 Jan;34(1):294-299.
- Delph KM, Beard LA, Trimble AC, Sutter ME, Timoney JF, Morrow JK. Strangles, convalescent Streptococcus equi subspecies equi M antibody titers, and presence of complications. J Vet Intern Med 2019 Jan;33(1):275-279.
- Boyle AG, Timoney JF, Newton JR, Hines MT, Waller AS, Buchanan BR. Streptococcus equi Infections in Horses: Guidelines for Treatment, Control, and Prevention of Strangles-Revised Consensus Statement. J Vet Intern Med 2018 Mar;32(2):633-647.
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