If you live in an area where equine strangles runs rampant, then you’re probably aware that vaccines against this infectious disease are less than perfect. This leaves many horses unprotected from the disease and/or at risk for developing vaccine reactions, including abscesses or purpura hemorrhagica (damaged, leaky blood vessels resulting in swelling).

There are currently two strangles vaccines available in the United States: one injectable and one intranasal. Unfortunately, despite aggressive efforts, neither can protect a horse against the disease 100% of the time. This leaves even vaccinated horses at risk, which can be problematic as strangles, caused by the bacterium Streptococcus equi subspecies equi, is one of the most frequently diagnosed equine infectious diseases worldwide.

“There is an urgent need to develop new preventative vaccines against strangles and, to date, our success in doing so has been limited,” said Andrew Waller, BSc, PhD, from the Animal Health Trust, in Newmarket, U.K.

Waller and colleagues set out to develop a strangles vaccine veterinarians could administer intramuscularly without abscesses developing at the injection site (a common problem)