New real-world evidence has provided encouraging insight into the effectiveness of Strangvac, the injectable vaccine for strangles, when used during an active disease outbreak.
A recently published report describes the outcomes of vaccinating clinically healthy horses with Strangvac during a confirmed strangles outbreak on a farm in Sweden. The findings offer valuable reassurance for horse owners, yard managers and veterinary professionals managing this highly contagious disease.
Key findings from the outbreak study
The report highlighted several important outcomes following vaccination:
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No vaccinated horses developed clinical strangles, remaining healthy throughout the outbreak
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This protection was observed despite ongoing exposure to Streptococcus equi, confirmed by serological testing
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The outbreak was successfully contained, with no additional cases recorded on the premises
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Importantly, new arrivals to the yard also remained disease-free, suggesting effective control at a premises level
These results suggest that timely vaccination with Strangvac can play a valuable role not only in prevention, but also as part of a broader disease-management strategy during an outbreak.
What this means for UK horse owners and yards
Strangles remains one of the most common infectious diseases affecting horses in the UK, with outbreaks often leading to prolonged yard closures, movement restrictions and significant welfare concerns.
In the UK, two strangles vaccines are currently available:
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Strangvac – an intramuscular vaccine containing purified proteins from Streptococcus equi. It does not interfere with standard strangles blood testing (serology), making it particularly useful for yards that routinely screen horses.
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Equilis StrepE – a live attenuated vaccine administered via the nose, designed to stimulate local immunity in the upper respiratory tract.
Veterinary advice is essential when deciding which vaccine is most appropriate, particularly during an outbreak or on high-risk premises.
Improving yard biosecurity
This new evidence reinforces the importance of vaccination as part of a layered biosecurity approach, which should also include:
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Pre-arrival screening and isolation of new horses
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Prompt investigation of nasal discharge, fever or lymph node swelling
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Regular monitoring of temperatures
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Clear protocols for movement on and off the yard
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Good hygiene practices for equipment, hands and clothing
Vaccination alone cannot replace good management, but it can significantly reduce disease impact, limit spread and help protect both resident and visiting horses.
Further information
Horse owners and professionals can find more detail and access the full research paper via BEVA here, and find more information on equine diseases and their monitoring on the Equine Infectious Disease Surveillance (EIDS) website, which provides up-to-date, evidence-based information on disease outbreaks, vaccination and biosecurity guidance.
As understanding of strangles continues to evolve, studies like this offer practical reassurance that vaccination, when used appropriately, can be a powerful tool in protecting horses and maintaining safe, resilient equestrian yards.