New Studies Demonstrate The Benefits Of Strangvac Vaccination During Strangles Outbreaks
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New studies1, 2 have highlighted the benefits of vaccination with Strangvac in the face of equine strangles outbreaks.
The published studies identified the benefits of Strangvac vaccination during strangles outbreaks on two different yards in Sweden.
In one study1, no horses developed signs of strangles after the second vaccination with Strangvac was administered. The outbreak occured on a busy competition yard after the introduction of a new horse without an isolation period, nor pre-movement blood ELISA screening for recent S. equi exposure. Fortunately, a combination of strangles vaccination and biosecurity measures was effective to limit the transmission and clinical impact of strangles in this recently vaccinated herd, as no horses developed signs of strangles after the second vaccination. Strangles vaccination is now mandatory on this yard and no further cases of strangles have occurred on the premises.
In a separate outbreak in Sweden, strangles was confirmed in three unvaccinated and unwell horses2. As a result of the outbreak, multiple (17) healthy horses on the same yard were vaccinated with Strangvac. Thanks to the unique DIVA (Differentiate Infected vs Vaccinated Animals) capability of Strangvac, vaccination status does not affect the blood tests used by vets to assess recent equine exposure to S. equi. Interestingly, blood samples in this group of horses demonstrated recent exposure to S. equi in over half of the vaccinated horses. Yet despite recent exposure to the bacteria, none of the vaccinated horses developed strangles. Instead, all horses vaccinated during the outbreak responded to the vaccine components and remained healthy, suggesting a protective effect of vaccination of healthy horses with Strangvac in outbreak situations.
With the Surveillance of Equine Strangles3 data identifying a 77 per cent rise in diagnosed cases last year, strangles remains one of the most frequently diagnosed infectious diseases of horses worldwide and is a devastating threat to the equestrian industry, with 10 per cent of cases leading to death4.
“The UK experienced a steep rise in strangles cases last year,” comments Bex Glasgow, veterinary surgeon and equine veterinary advisor at Dechra, the company behind the Strangvac vaccine. “Strangles vaccination, alongside good biosecurity measures, are essential tools in disease prevention and recent studies have also demonstrated its protective effect during outbreak situations.”
Strangles Awareness Week, which is supported by Dechra, takes place from 4 to 10 May 2026 to raise awareness of the disease and the measures that can be put in place to prevent and manage outbreaks. The campaign’s important BEST practice messaging will help prevent spread of the disease:
- Boost immunity with strangles vaccination
- Engage with trusted information
- Separate unfamiliar horses
- Temperature check routinely
For further information on the Strangvac vaccine click here. For details on Strangles Awareness Week click here.
References
- Rask, Erika et al. “Closing the Stable Door on Strangles: Serological Responses of Vaccinated Horses on a Farm Following the Arrival of a New Horse.” Animals : an open access journal from MDPI vol. 15,24 3584. 13 Dec. 2025, doi:10.3390/ani15243584 https://pubmed.ncbi.nlm.nih.gov/41463869/
- Gröndahl G, Righetti F, Aspán A, Bjerketorp J, Frosth S, Frykberg L, et al. Reining in strangles: absence of disease in horses vaccinated with a DIVA-compatible recombinant fusion protein vaccine, Strangvac, following natural exposure to Streptococcus equi subspecies equi. Equine Vet J. 2025. https://doi.org/10.1111/evj.70125
- Surveillance of Equine Strangles network. https://equinesurveillance.org/ses/
- Boyle, A.G., Timoney, J.F., Newton, J.R., Hines, M.T., Waller, A.S. & Buchanan, B.R. (2018) Streptococcus equi infections in horses: guidelines for treatment, control, and prevention of strangles-revised consensus statement. Journal of Veterinary Internal Medicine, 32, 633–647; Duffee, L.R., Stefanovski, D., Boston, R.C. & Boyle, A.G. (2015) Predictor variables for and complications associated with Streptococcus equi subsp equi infection in horses. Journal of the American Veterinary Medical Association, 247, 1161-1168
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