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Veterinary
Infectious disease

Streptococcus equi infections: current best practice in the diagnosis and management of ‘strangles’

01 March 2021
Clinical
34 mins read
Figure 6. Purulent material lavaged from the guttural pouch using a Foley catheter. Note the attempt to catch infected material in a bowl but the disappointing lack of gloves, personal protective equipment and floor covering.
Figure 6. Purulent material lavaged from the guttural pouch using a Foley catheter. Note the attempt to catch infected material in a bowl but the disappointing lack of gloves, personal protective equipment and floor covering.

Abstract

Foreword

This document was commissioned to provide UK veterinary surgeons with up-to-date information on Streptococcus equi infection and to provide practical recommendations for veterinary surgeons in the field. The participants were selected to provide representation from a range of expertise and viewpoints and included practitioners, academics and social scientists. The document and practical recommendations were developed using a modified non-anonymised two-round Delphi process, considering published and unpublished research relating to ‘strangles’ using online discussion. The expert group was convened by UK-Vet Equine and Redwings and an online meeting held on 20th January 2021 with sponsorship from MSD and support from World Horse Welfare. The sponsors did not participate in the meeting and had no influence over editorial content. Each of the panellists was provided with a sub-topic and presented a review of the evidence pertaining to that area prior to taking two rounds of questions relating to the evidence presented. Where research evidence was conflicting or absent, collective expert opinion, based on the experience of the group, was applied. The opinions expressed are the consensus of views expressed by the authors who all approved the final manuscript. Where it was not possible to reach consensus, different viewpoints are presented.

Streptococcus equi subsp. equi (henceforth termed S. equi) is responsible for the clinical condition known colloquially as ‘strangles’, a highly contagious disease that is endemic worldwide with only a handful of countries being free of the condition. Fatality rates have been reported at between 1 and 10%, and rates of morbidity are far higher (Boyle et al, 2018). Strangles causes profound disruption and economic losses to the equine industry, and is one of the most challenging equine infectious diseases to manage.

S. equi is an obligate pathogen that does not survive well outside the horse. Elimination of the disease should be a realistic aim; in some countries, strangles is a reportable or notifiable disease. A major factor in S. equi's success as an equine pathogen is its ability to survive in, and spread from, horses that are not exhibiting clinical signs. Transmission from outwardly healthy horses is likely to be of greater importance than transmission from horses with clinical signs; therefore, identification of these horses and elimination of infection is critical in preventing new outbreaks.

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