Streptococcus equi subspecies equi (S. equi) is the bacterium which causes the highly contagious disease strangles (also known as “distemper”). Strangles commonly affects young horses (weanlings and yearlings), but horses of any age can be infected. Vaccination against S. equi is recommended on premises where strangles is a persistent endemic problem or for horses that are expected to be at high risk of exposure.

Resource Type

  • Guideline


  • Infectious Diseases
  • Strangles
  • Vaccinations

Publish Date

January 1, 2020