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The Veterinary record1997; 140(4); 84-90; doi: 10.1136/vr.140.4.84

Naturally occurring persistent and asymptomatic infection of the guttural pouches of horses with Streptococcus equi.

Abstract: During an outbreak of strangles on a farm with approximately 1500 horses, the spread of Streptococcus equi infection was monitored by repeated nasopharyngeal swabbing and culture. In order to control the infection and prevent new introductions of strangles on to the premises, a system of quarantine and swabbing of cases and all incoming animals was instituted. Long-term carriage of the organism was detected in four clinically healthy convalescent animals, and in two of 350 new ponies; it persisted for between seven and 39 months, but it was detected only intermittently by the culture of swabs which was a much less sensitive method than the culture of guttural pouch lavages taken by endoscopy (45 per cent v 88 per cent sensitivity, respectively, for any single sample). Repeated swabs were often negative for several weeks between positive samples. Nonetheless, in all but one of the long-term carriers, S equi was detected by culture of repeated swabs taken over a period of less than two to three months. Infection was detected unilaterally in the guttural pouches of five of the carriers and was accompanied by large numbers of neutrophils in the lavage samples whether or not there was empyema. Abnormalities of the affected guttural pouches were detectable by radiography but only after the instillation of contrast medium. The study indicated that clinically healthy long-term carriers of S equi present a serious risk of spreading strangles, particularly because they may be detected only by repeated nasopharyngeal swabbing over two to three months.
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Publication Date: 1997-01-25 PubMed ID: 9032908DOI: 10.1136/vr.140.4.84Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates the prolonged presence of Streptococcus equi bacteria in horses which can lead to strangles, a contagious disease amongst horses, even when they appear clinically healthy.

Introduction and Objectives

  • The aim of the study was to monitor and control the spread of Streptococcus equi infection in horses during an outbreak of strangles on a farm with about 1500 horses. The researchers wanted to discern the role of seemingly healthy horses, which might in fact be long-term carriers of the bacterium, in transmitting the disease.

Methods

  • The researchers employed nasopharyngeal swabbing and culture methods for monitoring the spread of infection.
  • To prevent the introduction of new cases, a system of quarantine was instituted for all the previously affected and newly incoming animals.
  • The detection of the bacterium involved the culture of guttural pouch lavages taken by endoscopy and was compared with the culture of swabs.
  • Radiography was implemented, post the instillation of a contrast medium, to identify abnormalities of the guttural pouches affected.

Findings

  • The researchers detected long-term carriage of the bacterium in four clinically healthy animals and in two of the 350 new ponies, with the bacteria persisting for between seven and 39 months.
  • The culture of guttural pouch lavages was found to be a more sensitive method of detection compared to swab cultures. In other words, the bacteria were detected more frequently (88% sensitivity) using this method than with swabs (45% sensitivity).
  • Repeated swabs were often found to be negative for several weeks between positive samples, making detection through this method intermittent.
  • The infection was found to be unilateral in the guttural pouches of five carriers and was associated with large numbers of neutrophils.
  • Abnormalities of the guttural pouches infected could only be detected via radiography after the instillation of a contrast medium.

Conclusion

  • The study concluded that horses appearing healthy clinically could still be long-term carriers of Streptococcus equi and pose a serious risk of spreading strangles.
  • Such carriers could only be detected by repetitive nasopharyngeal swabbing over a period of two to three months.

Cite This Article

APA
Newton JR, Wood JL, Dunn KA, DeBrauwere MN, Chanter N. (1997). Naturally occurring persistent and asymptomatic infection of the guttural pouches of horses with Streptococcus equi. Vet Rec, 140(4), 84-90. https://doi.org/10.1136/vr.140.4.84

Publication

The Veterinary record
ISSN: 0042-4900
NlmUniqueID: 0031164
Country: England
Language: English
Volume: 140
Issue: 4
Pages: 84-90

Researcher Affiliations

Newton, J R
  • Centre for Preventive Medicine, Animal Health Trust, Newmarket, Suffolk.
Wood, J L
    Dunn, K A
      DeBrauwere, M N
        Chanter, N

          MeSH Terms

          • Animals
          • Carrier State / diagnosis
          • Carrier State / epidemiology
          • Carrier State / veterinary
          • Disease Outbreaks / veterinary
          • Female
          • Horse Diseases / diagnosis
          • Horse Diseases / epidemiology
          • Horse Diseases / pathology
          • Horses
          • Male
          • Nasopharynx / diagnostic imaging
          • Nasopharynx / microbiology
          • Nasopharynx / pathology
          • Neutrophils / pathology
          • Pharyngeal Diseases / diagnosis
          • Pharyngeal Diseases / epidemiology
          • Pharyngeal Diseases / veterinary
          • Radiography
          • Sensitivity and Specificity
          • Streptococcal Infections / diagnosis
          • Streptococcal Infections / epidemiology
          • Streptococcal Infections / veterinary
          • Streptococcus equi / isolation & purification
          • Therapeutic Irrigation / methods
          • Therapeutic Irrigation / veterinary

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