Work

Closing the Stable Door on Strangles: Serological Responses of Vaccinated Horses on a Farm Following the Arrival of a New Horse

Year: 2025

Type: article

Abstract: Infection of horses with Streptococcus equi subspecies equi (S. equi), the causative agent of strangles, is associated with the movement of horses from one farm to another, or the attendance of equestrian events and sales. Strangles can affect all horses on a farm, leading to the death of up to 10% of cases depending on the success of biosecurity measures and the use of vaccination. This retrospective study used ELISAs to measure the exposure of horses to S. equi at a farm that experienced an outbreak of strangles shortly after the introduction of a new horse on the same day that the majority of the 17 resident horses were vaccinated with Strangvac for the first time. One vaccinated horse, which subsequently tested positive for S. equi and EHV-4, developed a cough, elevated body temperature and nasal discharge 11 days after first vaccination. Two other horses developed fever for one day at 22 days post-first vaccination, but only one had serological evidence of exposure to S. equi. All vaccinated horses had high antibody titres to vaccine components, whilst seven of the 17 resident horses, and the new arrival, tested seropositive for exposure to S. equi. Although three out of the 17 vaccinated horses developed mild signs of disease before second vaccination, serological data support the effectiveness of vaccination in resident populations of horses to minimise the risk of strangles following the introduction of a new horse.

Source: Animals

DOI: 10.3390/ani15243584