Strangles vaccine offers year of immunity – study

A vaccine against equine strangles offers “significant protection” for a year or more, a new study has shown.

Researchers retrospectively analysed the antibody responses of horses vaccinated with Strangvac.

They derived data from seven independent clinical trials, comprised of six experimental infection studies involving 129 ponies (80 vaccinated controls and 49 unvaccinated) and a serology study of 12 vaccinated ponies which were not experimentally infected.

Protection

All of the unvaccinated ponies developed pyrexia, with 46 out of 49 (93.9%) doing so within nine days of strangles infection.

Just 17 of the 80 (21.3%) vaccinated ponies developed pyrexia within nine days, while 37 (46.3%) did not develop it at all during the study periods.

The scholars found antibody titres demonstrated protection of 78.9% to 81.2% in vaccinated animals one year after the second dose of Strangvac.

Increasing cases

Surveillance of Equine Strangles data shows 290 cases of strangles were diagnosed in the UK between January and June this year, an average of 48 per month, compared with 479 total cases recorded in 2025 and already surpassing the 271 cases in 2024.

Recent studies have also showcased Strangvac’s efficacy during outbreak situations.

Veterinary surgeon Mary Battersby, equine veterinary advisor at Dechra, the manufacturer of the Strangvac vaccine, said: “The new study provides further evidence that annual Strangvac boosters offer significant protection against strangles and can be integrated into annual vet check-ups to encourage uptake.”